- Author: Linda Carloni
Tomatoes are one of our most popular and best-loved garden plants, but they do have their issues, which vary depending on variety, climate, soil, time of the season and your overall garden environment. Problems may happen despite the best care you can give them. This blog focuses on managing tomato problems common in Alameda County in mid-summer.
The problems are sorted by where you will first see it appear on the plant. The problem may also cause symptoms on other parts of the plant.
Tomato Problems Seen on Leaves
Early blight
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Damage. Early blight symptoms include black or brown spots, not quite half an inch wide on leaves, stems, or fruit. Leaf spots are leathery and frequently have concentric rings. The spots generally appear on the oldest leaves, at the bottom of the plant. Early blight tends to crop up whenever the leaves become wet and can't dry off quickly. Early blight is more common in coastal regions because of fog, humidity and frequent cool weather.
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Management/Prevention. The most important action is to avoid overhead watering. Water the soil, not the plant. Try to water early in the morning, so any water on the leaves has a chance to evaporate. Cut off the damaged leaves, so long as you can still retain a good canopy.
Late blight
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Damage. Late blight occurs most often in coastal areas. Leaf damage starts as spots (of various colors) that look water-soaked and are surrounded by yellowish areas. This progresses to curled, tannish and dead leaves. This blight, too, is encouraged by wet leaves.
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Management/Prevention. Again, the most important action is to avoid overhead irrigation. Copper fungicides may provide control if applied at the first sign of infection and reapplied every 7 to 10 days. Promote air circulation, prune the plant if needed to get airflow. The Phytophthora fungus that causes late blight spreads easily, so carefully dispose of all debris from infected plants once you have harvested. The spores can spread among your nightshades (tomatoes, tomatillos, peppers, eggplant, potatoes, and other plants in this family. ).
Powdery mildew
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Damage. Powdery Mildew looks different on tomato leaves than on many vegetables. On tomato leaves, the fungus starts as yellow blotches, which progress to brown. There may or may not be the fuzzy whitish/grayish patches common on other vegetables. In severe cases, you can sometimes see mildewed spots on the main stem.
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Management/Prevention. Warm days and cool nights and temperatures from 68° to 86°F benefit the fungus. Fog encourages it; higher temperatures may kill it. Powdery mildew grows best in shady conditions, so planting in the fullest sun you can find can help prevent it. Severe infestations may be managed with sulfur-based pesticides, some of which qualify for organic treatment. Always follow the package instructions when you apply any pesticide.
Whiteflies
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Damage. Whiteflies damage the plant by piercing and sucking sap out of the leaves and stems. The leaves may turn yellow, appear dry or fall off. Whiteflies excrete a sticky substance called honeydew that can attract a dark sooty mold, impairing the leaves' photosynthesis and stunting growth.
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Management/Prevention. Once a whitefly population is established, it can be hard to manage, so prevention and early response are most important. In many gardens, whiteflies are suppressed by their natural insect enemies. Cultivating these desired insects requires no use of broad-spectrum insecticides (like organophosphates, carbamates, and pyrethroids) and managing ants. Broad-spectrum insecticides, particularly systemic insecticides, will kill many natural insect enemies that you want, as well as the ones you don't want. Managing ants is important b/c the ants will protect insects that cause honeydew (which the ants eat) against their natural enemies, preventing them from doing their jobs.
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Whiteflies can also be discouraged by reflective mulch (paper, plastic or fabric), which can be home-made or purchased in rolls. Small numbers of whiteflies can also be managed by hosing the plants down by spraying with the hose; multiple sprays may be needed. It can be difficult to effectively manage whiteflies with less-toxic oils and soaps, because only the whiteflies that the spray touches are affected.
Verticillium and Fusarium Wilts
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Damage. Verticilium wilt is signaled by yellowing in the older leaves and wilting of shoot tips during the warmth of the day. Leaves start to curl up and often fall. Wilting becomes worse and the plant's condition becomes quite poor; it may die. For Fusarium wilt, early symptoms are bright yellow leaves, generally just on one side or one branch, often on only one side of the leaf. As it progresses, the foliage yellows, wilts and then turns brown. The entire plant dies. Both are widespread. Fusarium affects tomatoes; verticillium affects many garden plants.
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Management/Prevention. Both Fusarium and Verticillium are caused by soil-borne fungi that affect the plant through the roots and disrupt the tissues that conduct water through the plant. Nothing can be done for tomatoes already infected with one of these two wilts. No fungicides are available to control these diseases. Even worse, these wilts can live in the soil for many years to infect susceptible new plants - tomatoes, potatoes, tomatillos, eggplant, peppers and many more. The best prevention is to remove all debris from infected plants, then use resistant plant varieties. You can determine if the variety is resistant by reading the plant label or seed packet, on which:
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V means resistance to Verticillium,
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F to Fusarium and
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N to nematodes.
If you live in an area warm enough, soil solarization can help clean up the soil. To solarize, you cover an area with clear plastic for 4 to 6 weeks during a hot period of the year when the soil receives direct sunlight.
Leaf rolling
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Damage. Tomato leaves curling upward.
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Management and prevention. Tomato leaf curl can have many causes, so the first course of action is to determine why it's happening.
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In spring when the weather is still cool and wet, the leaves may become firm and leathery and curl up. If this is the cause, the symptoms will resolve with no lasting damage when the weather warms and the soil dries.
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If it's a very hot afternoon, but the soil is still damp an inch and more down, the tomato may just be unable to take in enough water to offset the water being lost through the underside of the leaves. The leaves should uncurl in the evening with no lasting damage. But if it's hot and the soil is dry, it's time to water.
Unfortunately, there are more serious causes of upward leaf roll - be sure to check a few of the rolled leaves to make sure there isn't an insect or caterpillar cocoon in there. Leaf curl can also be a symptom of overwatering leading to root rot, or an early sign of verticillium, so continue monitoring.
Less common leaf issues
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Aphids can cause curling, yellowing and distortion of leaves, as well as a black mold on a sticky residue they excrete. You'll typically see the tiny insects as well. Hosing leaves down and beneficial insects can reduce this problem. Comprehensive information on aphid management
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Viruses tend to cause mottling - yellow, white or light green - on the leaves, and may cause leaf distortion. Tobacco mosaic virus
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Flea beetles feed on leaves, leaving tiny pits or small holes. A bad infestation can cover leaves with bleached pitted areas. This is generally the most serious in seedlings, which can be covered when young to prevent damage. More on flea beetles
Tomato Fruit Damage Causes
Hornworms
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Damage. To my mind, hornworms are the worst tomato problem. They can break your heart, chomping up that almost ripe tomato you were planning to eat next week.
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Hornworms grow to be large striped green caterpillars and have a small horn on the rear end. Despite their size, they are surprisingly hard to find. The first sign you see may be large black or dark green droppings under the plant. Hornworms also chew up the leaves.
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Management and prevention. Hornworms can be snipped with shears or squished with a foot. Crows and chickens love them for dinner. The pesticides Bt (Bacillus thuringinesis) and spinosad can be effective when the caterpillars are small. Natural enemy insects can keep the population down too. Monitoring is crucial to catch the problem early.
Blossom End Rot
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Damage. Blossom end rot is caused by environmental conditions; generally those affecting the water and calcium in the fruits as they develop. It causes a brown, sunken, leathery spot at the blossom end of the fruit, and is most common in sandy soils.
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Management and prevention. The problem is aggravated by high soil salt content and inconsistent watering. To minimize the problem, monitor your soil (especially if the plants are in pots) to make sure the root zone remains moist, and water only when it is getting dry. If your soil tests as deficient in calcium (most do not), adding calcium to the soil may help, but a calcium deficit is usually not the cause. Don't over-fertilize. For prevention, add lots of compost to your soil when planting to help retain water.
Sunscald
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Damage. While tomatoes like the sun, they can still get “burned.” Overexposure to sunlight can cause the fruit to become tan and tough on the side where the sun hits. This is more of a problem for plants that have a lot of bright afternoon sun or have been seriously pruned.
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Management and prevention. Enough (but not too much) moisture and fertilizer are important to keep the leaves growing well to shade the fruit. Avoid too much pruning as well. If the plants get full, intense afternoon sun, consider adding a bit of afternoon shade with an umbrella or shade cloth.
Fruit cracking / Catfacing
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Damage. The surface of the fruit can crack: in a spoke-like pattern out from the stem, in a circular pattern at the stem end, or at the blossom end.
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Management and prevention. These tend to be caused by environmental extremes: rain following long dry periods; high temperatures coupled with high soil moisture, resulting in very fast growth; wide fluctuations in soil moisture; abnormally hot or cold conditions. Many of these we have no control over, but the following can help: choosing varieties adapted to your climate; keeping the soil evenly moist; heavy mulching (3 to 4 inches, but always at least a couple of inches away from the stem) to moderate the soil temperature; maintaining good leaf cover.
Symptoms Affecting the Whole Plant
Failure to Thrive
Sometimes tomato plants just don't do well. There may be loss of vigor, with the plant not growing as well as the others nearby; smaller leaves and fruit than the neighboring plants; wilting even when the soil is moist (without leaf problems); and/or overall leaf yellowing.
Possible causes include problems in care and:
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Root-knot nematodes (microscopic roundworms)
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You can confirm root-knot nematodes by looking at the roots or viewing soil under a microscope. Root-knot nematodes cause distinctive galls on the roots, pictured above. It's difficult to manage nematodes. Prevention steps: only using nematode-free plants from reliable nurseries and only planting nematode-resistant varieties (marked N on the plant tag or seed packet). To keep nematodes from spreading, don't move nematode-infested plants and don't allow irrigation water to spread from an infested area. To reduce the level of nematodes, a combination of planting resistant varieties, fallowing (leaving the soil empty but moist and free of weeds) and soil solarization (if you live in a warm enough area) can be effective. More info on this technique.
Failure to fruit in summer
This very disappointing problem can have several causes:
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Too much nitrogen fertilizer
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Not enough light - tomatoes really need at least 6 hours of sunlight each day
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Cool nights - under 55 degrees
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Consistent high daytime heat - over 90 degrees.
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Not enough warmth - Tomato plants thrive in daytime temperatures between 80 and 90 degrees.
The last three problems can be greatly mitigated by planting an appropriate variety. Some varieties withstand heat better. The Marin Master Gardeners recommend Heatmaster, Solar Fire, Summer Set and Phoenix for hot areas. For colder climates, varieties with fewer days to maturity (including most cherry tomatoes) tend to do better.
Major sudden damage
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If you come out to your garden one afternoon and there are significant holes in the ripe tomatoes, it may be a mammal.
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Particularly if the tomato is removed from the plant, your pest may be birds or a mammal. Rabbits, squirrels, birds and rats are known tomato munchers.
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Hornworms cause large but shallow damage. Here is a guide to figuring out which critter it is and how to manage them.
You are unlikely to see all of these problems in one season; maybe you will be fortunate and you won't see any. Hopefully, whatever does occur will be quickly managed!
References
- Tomato plant problems and how to solve them by the Marin Master Gardeners
- Tomato diseases in the home garden by the Contra Costa Master Gardeners
- UC IPM for home gardens, tomatoes
Have a gardening question? We'll help. You can reach us by:
- Emailing acmg@ucanr.edu. Please include a photo of the problem, if you can, plus your name, phone number, city and a description of the problem.
- Using our online form.
- By phone, during our office hours, 10 am to noon Wednesday and 11 am to 1 pm Thursday: 510-670-5645. At other times, please leave a message and we'll return your call during our office hours.
- In person at our Hayward office, during our office hours, only by appointment.
- Author: Linda Carloni
Tomatoes are one of our most popular and best-loved garden plants, but they do have their needs. Because a tomato crop can be so deliciously rewarding, many of us are happy to devote extra energy to manage this wonderful crop. It's warm, and your tomatoes are growing, starting to flower and fruit. This post discusses what you should be doing now to take care of those plants. If you have already seen a problem on your tomatoes, you may want to go first to the companion piece - Managing Midsummer Tomato Problems.
Summer Tomato Care
Watering
Enough but not too much is the key. While tomato seedlings should be kept moist all the time when planted, after 3 to 4 weeks you should taper down. Established plants should be watered just after the top few inches of soil have dried. Water so that the whole root zone becomes thoroughly moist. Temperature plays a huge role in how much water your plant needs. Think of the difference in temperature, and thus water needs between the cities of Pleasanton and Alameda, just in our county! How often and how much to water also depends on the type of soil, whether it is windy, and the depth to which the plant has rooted. Remember, plants in pots will need to be watered more often because there is less soil from which the roots can draw water and because pots dry out faster.
A hand-held moisture meter (typically 6”to 8”in length) can be very helpful in determining when to water. These are not precise, but are widely available and relatively inexpensive and can give you a general idea. Even simpler, you can stick your finger in the soil several (3 to 6) inches down and see if the soil is moist. Overwatering can cause leaf wilting, root rot, and catfacing or cracking of your tomatoes. Underwatering causes leaves to look wilted, blossoms to dry up and fall off, and growth to slow. Inconsistent watering exacerbates blossom end rot. So it's important to put in the extra effort to get it right.
To keep that water where you want it, check the mulch around your plant. A few inches of mulch on the surface, starting 2 or three inches from the stem, really helps diminish loss from evaporation, helping you achieve that even moisture you want.
Take care not to get the leaves wet, which can lead to leaf fungal diseases. Water the soil, not the plant.
Support
You probably put a tomato cage around your plants or put in a stake or stakes to tie them too. Great job - all tomatoes need support! In the summer, you need to check (more than once) to make sure that initial support remains adequate. As the plants grow, they send out lots of branches that will try to sneak out of their supporting structure. This is particularly an issue with indeterminate vining plants, but the bushier determinants can also evade your efforts. Standard commercial cages are frequently insufficient for a large and vigorous tomato plant. To add additional support, you can gently tie errant branches to the existing supports and/or add additional stakes and tie to them. Heavy-duty cages and super large heavy-duty cages (photo above) provide a lot more support.
Pruning
Why prune?
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Any leaves at the bottom of the plant that are touching or almost touching the ground should be pruned. Tomatoes can contract diseases through leaves that touch the ground. These low branches occur because tomatoes need to be planted deep. A good rule of thumb is to remove branches that start less than four inches above the ground.
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Determinate tomatoes should not be pruned except for the lowest branches as described above. All the fruit on determinants comes at once, and pruning would sacrifice some of that fruit.
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Always make sure you keep enough leaves for photosynthesis, which takes place in the leaves and feeds the plant.
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You also need enough leaves to shade the tomatoes to avoid sunscald.
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If you grow in an area where the leaves may get damp from rain or fog, pruning the plant for air circulation will help minimize the tomato maladies exacerbated by humidity and wet leaves. In Alameda County, this is particularly important in the foggy moderate climate Bayside areas.
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If the plant becomes very dense, you may need to prune out some branches in the middle so that sunlight can penetrate to the inside of the plant.
Other than the reasons above, it's really a question of personal preference.
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Pruning gives you the ability to train the tomatoes up in a narrow shape. This lets you plant more tomatoes in a given space.
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Pruning gives you larger early tomatoes, although fewer tomatoes overall.
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Pruning directs more energy to making the fruit rather than growing foliage.
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If you are supporting a large indeterminate tomato using a standard commercial tomato cage or staking, you may need to prune so that the cage or stakes can carry the weight of a fully laden plant.
However,
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Pruning is more work!
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Pruning may make the tomatoes more susceptible to sunscald.
Here's a nice video on pros and cons of pruning from a sister Master Gardener program
Fertilizing
Even if you've fertilized your tomatoes when they were planted (recommended), tomatoes generally need additional fertilizing, starting once they have flowered and set some fruit. When that happens, add some tomato fertilizer that has potassium and phosphorus as well as nitrogen. Always follow the package directions. Make sure the soil is thoroughly moistened, scratch the fertilizer into the top part of the soil without disturbing the roots, and water it in. Depending on how long your tomato is bearing and growing, you may want to repeat this, but not more often than every four to six weeks.
Resources on fertilizing:
- Fertilizing 101
- Is it time to fertilize?
- Feeding the soil, not the plant
- General information on fertilizing and soil from California Garden Web
Following the fertilizing instructions help you keep your tomatoes vigorous and growing. But despite your best efforts, pests, diseases and other problems happen. Here's a guide to managing those problems.
General Tomato Resources
Care
Selection
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- Author: Jim Farr
(Editor Note: This blog first appeared in August, 2021 - it has been slightly modified for our current heat wave in July 2024)
This current July heat wave may have stressed your irrigation effectiveness and made you question your landscape plant selection. Even in this type of heat, being water-smart is a good strategy and we have tips that you can begin using today.
According to a University of California Report, residential landscape irrigation is estimated to account for about 50% of annual residential water consumption in California. While that amount varies widely from about 30% in many coastal communities to 60% or more in various inland suburban communities, bottom line, that is a lot of water.
So what can you do right now to save water and make a difference? You might be surprised by the steps you can take immediately that do not take much time or cost and will make a noticeable difference in your water usage. These steps apply to container gardening as well as in-ground landscaping. Some references specific to container gardening are given at the end of the article.
Where to Begin Saving Water In Your Garden
Tip One: Find Out How Much Water Your Landscape is Using
This will give you a benchmark to measure the impact of your water-saving efforts which will help encourage and motivate you as you see the things you are doing are really making a difference.
Measuring your landscape water usage can be a little difficult but there are ways to do it without spending a lot of time with paper and pencil.
If your city subscribes to Aquahawk your task is simple. Aquahawk is an online tool that can measure real-time water usage and makes figuring out your water usage as simple as logging in with your id and password. Unfortunately, only a handful of cities (mostly in the Tri-Valley) have access to Aquahawk.
If you don't have Aquahawk, then another way to estimate water usage is to pull up your water bills (hard copy or get online) and review your historic water usage. Assuming your landscape watering is minimal in winter, compare average water use in winter with average water use in the summer months. Given that other habits remain relatively constant, like washing dishes, laundry, showers, toilet flushes etc. then the difference will be primarily the water you are using for your landscape.
The Center for Landscape and Horticulture offer several online water calculators but these can be a little daunting to work through.
Now that you know your water usage, let's see how you can start to save water.
Tip Two: Mulch, Mulch, Mulch
This cannot be emphasized enough. Mulching has been described as the gardener's best friend and this is not an exaggeration. Imagine being able to minimize water usage by helping to slow down evaporation, reduce maintenance and weeds. In addition, cool the temperature of the soil and improve soil quality and fertility and even improve the look of your landscape! This is the magic of mulch. Mulching works for soils in raised beds and containers too.
What is mulch? Mulch is any material that is put on the surface of the soil to prevent water evaporation. Typically it may be straw or alfalfa pellets, wood chips, barks or hulls, or organic yard waste such as leaves or grass clippings. Mulch can be obtained free from your yard by using leaves or grass clippings or purchased at any home garden store or nursery.
You can learn more about types of mulch from the Master Gardeners of Sonoma County. Here is a website that will give you everything you need to know to start mulching:
To be effective, pile mulch six to eight inches deep, tapering down to three inches deep near the stems or crowns of plants. Mulch should not touch the stems of plants but should be approximately 10 inches away.
Tip Three: Composting
While you are mulching, consider adding compost to the soil or your containers. Compost is essentially organic mulches that have broken down to the point where plants can uptake the nutrients. Composts are typically worked into the soil unlike mulches which are layered on top. Besides improving the quality of the soil, compost acts like a slow release fertilizer. This will minimize the amount of extra fertilizer you use saving both money and water because over fertilizing plants causes excessive growth which uses more water. Additionally, compost helps to retain water especially in sandy soils where there is very little retention of water.
Tip Four: Check Your Irrigation System
Another extremely important step in saving water and eliminating waste is to turn on your landscaping watering system and observe. Check for broken lines and drip emitters and if you are watering grass check that the sprayers are functioning and spraying where they are supposed to.
While you are checking irrigation sprayers and lines, see if any water goes onto the sidewalk and down the gutter. Water down the gutter is water wasted. If necessary adjust your sprayers and irrigation timers to avoid any runoff.
Tip Five: Adjust Irrigation Times
Another step that takes only a few minutes but can make a significant difference is to set irrigation timers to water only between the hours of 9 pm to 6 am. This will minimize evaporation from the daytime heat and will utilize the irrigation water much more efficiently.
When you do this, consider adjusting your run time down some. If you have been watering outside of these hours chances are very good that you will be able to shorten your run times for each station on the timer. Water dedicated to landscape can often be reduced by 20 to 40 percent because over irrigation is very common. Gradually reduce the amount of water applied over a few weeks - giving lawns, trees and plants time to adjust.
To measure if you are applying enough water, the surface of the soil should be dry between watering but slightly moist about 2 inches down. Use the finger test, put your finger in the soil down to the second knuckle and if the soil feels slightly moist but not damp and a little bit of the soil sticks to your finger, then you are applying the right amount of water.
Many people overwater their landscaping so cutting back may actually improve the health of your plants. The signs of overwatering or under-watering are similar so checking the soil is the best indicator of whether your plants are being over or under-watered.
Step Six: Consider Using Cycling and Soaking Settings on Your Irrigation Timer
Step Seven: Check Your Irrigation Frequently
After the initial check of the irrigation system, it is a good idea to check the system occasionally looking for any water that is going down the gutter or hitting the sidewalk. Sometimes water pressure changes slightly or sprayers get a little clogged and water goes where it is not intended even though they were fine a few weeks prior.
Step Eight: Consider Planting Drought-Tolerant Plants
Drought-tolerant plants are sometimes misunderstood, “drought tolerant” doesn't mean they look like desert plants but many drought-tolerant plants have a surprising amount of color, pleasant fragrance, attract beneficial insects, and some are even deer resistant. Remember to plant drought-tolerant plants in late Fall so they can take advantage of the winter rains. All new plants require more water to get established, even drought-tolerant plants.
There are a number of great resources for identifying drought-tolerant plants. Below are a few resources that are available by just a click away. One of my favorites is the Alameda County Outstanding Plant brochures which are available online.
I find these particularly helpful because the plants are narrowed down to the plants that are proven to grow well in Alameda County, most are drought-tolerant and are readily available at local nurseries. Because these are nice, compact lists of plants that fit onto one piece of paper, you can easily take them to a nursery and use them as a guide for choosing plants. Keep a copy in your car and you will never forget to bring the list to the garden store.
These are steps you can take right now that will save water and lower your watering bill without affecting the health of your plants. Most of these steps can be completed in under an hour and a few others can be a nice weekend project, such as mulching your garden. So start saving water now and you will be doing yourself and the state of California a very big favor!
Water Saving Tips References
Water Calculators
Water Use Research
University of California Urban Water Use Study
Drought-Tolerant Plant Selection
- Outstanding Plants for Alameda County
- UC Davis Arboretum All-Stars
- EBMUD Water Smart Plants
- Water Use Classification of Landscaping Species (WUCOLS) – Very comprehensive database with a great searching tool
Water Wise Tips for Container Gardens
- Self-Watering Containers - University of Maryland Extension
- Growing Vegetables in Containers - Master Gardeners of Contra Costa County (pdf document)
- Container Gardening 101 - Master Gardeners of Santa Clara County (pdf document)
Have a gardening question? We'll help. You can reach us by:
- Emailing acmg@ucanr.edu. Please include a photo of the problem, if you can, plus your name, phone number, city and a description of the problem.
- Using our online form.
- By phone, during our office hours, 10 am to noon Wednesday and 11 am to 1 pm Thursday: 510-670-5645. At other times, please leave a message and we'll return your call during our office hours.
- In person at our Hayward office, during our office hours, only by appointment.
- Author: James Farr
Soil testing is a helpful practice for gardeners aiming to achieve healthy plant growth and a bountiful harvest. Understanding the composition of your garden soil helps tailor gardening practices to meet the specific needs of your plants. This article provides an overview of laboratory soil testing, covering its importance, the key elements tested, how to collect a soil sample, and how to interpret the results.
Why Soil Testing is Important
Soil testing is valuable for several reasons:
- Nutrient Management: It provides detailed information about the nutrient content of the soil, enabling gardeners to apply the correct type and amount of fertilizer.
- pH Level Adjustment: Knowing the soil's pH level, which affects nutrient availability, allows gardeners to adjust it to the optimal range for their plants.
- Detecting Contaminants: Tests can reveal the presence of harmful contaminants like lead or other heavy metals, ensuring the safety of your garden produce.
- Cost Efficiency: By applying only the necessary fertilizers and amendments, gardeners can save money and prevent environmental pollution.
- Tailored Gardening Practices: Understanding soil health helps in making informed decisions, leading to better plant growth and yield.
- Troubleshoot Why Plants Aren't Thriving: If you've exhausted your attempts to amend soil with compost, a soil test can provide more detailed information to remedy the problem.
Key Elements Tested in Soil
A standard soil test can include analysis of the following elements:
- pH Level: Indicates the acidity or alkalinity of the soil.
- Macronutrients: Such as nitrogen (N), phosphorus (P), and potassium (K), which are crucial for plant growth.
- Micronutrients: Including elements like iron (Fe), manganese (Mn), and zinc (Zn), which plants need in smaller amounts.
- Organic Matter Content: Affects soil structure, nutrient availability, and water retention.
- Cation Exchange Capacity (CEC): Reflects the soil's ability to hold onto essential nutrients.
Collecting a Soil Sample
To obtain accurate soil test results, most labs will have specific instructions to follow. In general, These are the steps for collecting a soil sample:
- Choose the Right Time: The best time for soil sampling is when the soil is moist but not wet, typically in the spring or fall.
- Select the Area: If your garden has distinct areas with different crops, soil types, or problem spots, sample each area separately.
- Collect the Sample: Use a clean tool to take small amounts of soil from several spots within the sampling area. Mix these samples in a clean container to create a composite sample.
- Depth of Sampling: For lawns and gardens, a depth of 6-8 inches is appropriate. For trees and shrubs, sample at a depth of 6-12 inches.
Interpreting Soil Test Results
Soil test results will provide detailed information about the elements mentioned above. Here's how to interpret some of the key findings:
- pH Level: Most garden plants thrive in a pH range of 6.0 to 7.0. Values outside this range may require the application of lime (to raise pH) or sulfur (to lower pH).
- Nutrient Levels: The report will indicate whether nutrient levels are low, medium, high, or excessive. Low or medium levels suggest the need for supplementation, while high or excessive levels mean you should cut back on those nutrients.
- Recommendations: Most soil tests come with recommendations for amendments and fertilizers. Follow these guidelines to adjust nutrient levels and pH accordingly.
Soil testing is a powerful tool that empowers gardeners to make informed decisions about managing their garden soil. By understanding the specific needs of your soil, you can optimize plant health, improve yields, and contribute to the sustainability of your gardening practices. Whether you are a hobbyist or a professional gardener, soil testing is a practice that yields long-term benefits for your garden and the environment.
This blog post is brought to you by the Help Desk of the Master Gardeners of Alameda County. Subscribe to our blog!
Resources
- Cornell Guide to Soil Testing: https://cwmi.css.cornell.edu/guidetosoil.pdf
- University of California Division of Agriculture and Natural Resources – Soil Testing: https://ucanr.edu/sites/placernevadasmallfarms/files/142586.pdf
- UC Master Gardener Program of Alameda County: https://acmg.ucanr.edu/Over_the_Fence / Whats_In_Your_Soil/
- Soil 101: https://ucanr.edu/sites/soils/Soils_101/
- Soil Test Kits: https://ucanr.edu/sites/gardenweb/files/29075.pdf
- Evaluating and Testing Soil: https://marinmg.ucanr.edu/BASICS/SOIL_813/evaluate/
- Soil Health Testing: https://soilfertility.osu.edu/extension-and-outreach/soil-health-testing
Analytic Testing Laboratories for Home Gardeners
Soils, Water, Plants, Heavy Metals and More
- Contact the labs to confirm offered services, pricing and preferred procedures for sample collection.
- Testing labs vary in the types of available tests and recommendations they provide, if any. Be sure to ask for detailed information regarding tests, test fees and interpretation, and whether recommendations are included. Many of the websites provide supplemental information about tests and sampling.
- Resources regarding soils and soil testing:
A & L Western Laboratories, Inc. 1311 Woodland Avenue, Suite 1 Modesto, CA 95351 (209)529-4080 |
Test descriptions and fees available online.
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California Laboratory Services 3249 Fitgerald Road Rancho Cordova, CA 95742 (800) 638-7301 www.californialab.com |
Test descriptions and fees available online.
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Control Laboratories, Inc. 42 Hangar Way Watsonville, CA 95076 (831)724-5422 |
Test descriptions and fees available online under shipping info.
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Dellavalle Laboratory, Inc. 1910 W McKinley Ave., Ste. 110 Fresno, CA 93728 (800)228-9896 |
Test descriptions and fees available online. Call / email for fees.
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Fruit Growers Laboratory Inc 2500 Stagecoach Rd Stockton, CA 95215 (209) 942-0182 |
Test descriptions and fees available online.
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Harmony Farm Supply & Nursery 3244 Gravenstein Highway North Sebastapol, CA 95472 (707) 823-9125 |
Call for test availability, description and fees. https://www.harmonyfarm.com/services/
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Peaceful Valley Farm & Garden Supply 125 Clydesdale Court Grass Valley, CA 95945 (888)784-1722 |
Test descriptions and fees online.
Videos of explanation of professional soil testing & results: https://www.groworganic.com/organic-gardening/videos/ Professional soil testing: |
Perry Laboratory 424 Airport Blvd Watsonville, CA 95076 (831)722-7606 |
Test descriptions and fees available online.
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Wallace Laboratories 365 Coral Circle El Segundo, CA 90245 (310)615-0116 |
In-depth explanations of test descriptions and fees available online: http://us.wlabs.com/services/
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Waypoint Analytical, Inc. (formerly Soil and Plant Lab) 4741 E Hunter Ave Ste A Anaheim, CA 92807 (714) 282-8777 |
Test descriptions and fees available online: Some videos: http://www.waypointanalytical.com/Videos
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Have a gardening question? We'll help. You can reach us by:
- Emailing acmg@ucanr.edu. Please include a photo of the problem, if you can, plus your name, phone number, city and a description of the problem.
- Using our online form.
- By phone, during our office hours, 10 am to noon Wednesday and 11 am to 1 pm Thursday: 510-670-5645. At other times, please leave a message and we'll return your call during our office hours.
- In person at our Hayward office, during our office hours, only by appointment.
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- Author: Erin Wright
No matter what you grow - trees, shrubs, flowers, veggies, turf areas - they all require some kind of irrigation in our Mediterranean climate. We had a good and late rainy season this year, so our plants were happy when the growing season kicked off and moisture ‘banks' were full. Dry and warm days are here, so now is a good time to test your sprinkler and irrigation systems to keep your garden happy and beautiful. Watering is one of the key cultural problems (culture in gardening means those activities involved in siting, selecting and caring for plants) master gardeners will ask about as they help to diagnose plant problems. Proper watering can keep some plant problems under control. Keeping ahead of irrigation problems by checking each sprinkler, drip head, or micro sprayer in your garden will ensure your plants receive the proper water to thrive and provide beauty, shade and food for your summer enjoyment.
Use this handy checklist and basic troubleshooting guide to check your watering system.
Warm Season Irrigation Checklist
Walk Your Garden
A visual inspection can help you identify problems with your irrigation system.
- Look for stunted or wilted plants that indicate a clogged or misaimed emitter or sprinkler.
- Turf areas will turn a dull gray color as they get too dry. Conduct a sprinkler/irrigation station test to reveal if there is enough water coverage for that spot. To test, turn on each irrigation station in sequence and observe the results.
- Check your plants for pests since plants suffering from under watering or over watering are more susceptible to pests and disease.
- Pay special attention to how much water is distributed during the station/zone test (see details below). Observe if all the plants are getting sufficient water, or if there is pooling under the plants or runoff onto the sidewalks
- Check any historic problem areas to ensure adequate irrigation coverage.
Irrigation Controls/Timers
If you have an automated sprinkler timer, here are the things to check as you head into the new growing season.
- If you turned off the system for the winter, turn the system back on.
- Replace the battery if your timer has one.
- Set the clock to the proper time and year.
- Check the timing for each valve and zone program
- Set time based on plant needs. You can find watering guidelines below in the Resources section.
- Set watering days and times of the week to match your water agency's watering guidelines/restrictions.
- Test each station/zone on your sprinkler timer (see below for troubleshooting repairs)
Sprinklers
Your station test from above should have helped you identify problems with your system.
- Replace broken sprinkler head “geysers” with a new sprinkler head. Most common sprinklers are easy to replace by untwisting the sprinkler from the riser (the part attached to underground piping) and replacing with the same type. Your sprinkler type may allow you to replace just the watering head. Check the manufacturer's website for full instructions.
- Use the same type of sprinkler in each zone. Not all popup sprinklers deliver the same volume.
- Use Teflon tape in the threads of the riser to ensure a leak-free seal.
- Adjust the sprinkler radius and spray pattern to get full coverage to reduce dry areas and water waste. You can find instructions for sprinkler adjustments on the sprinkler manufacturer's website as many offer instructional videos for the DIYer.
- Modern or smart sprinkler timers offer advanced settings to optimize how you water your garden. One feature, ‘cycle and soak' allows you to divide the total irrigation time into shorter intervals so the water has time to soak in. This setting is valuable for lawn areas as it promotes deep watering for root health. This also works well in sloped yards, raised beds, or heavy soils, preventing wasteful runoff. Even if your system doesn't have this feature, you can schedule several short consecutive watering times that provide the same effect.
Drip Systems
- Clean or replace clogged micro-spray heads.
- Adjust micro-spray head aim and coverage area. Squirrels, household pets and other garden visitors can knock them out of aim.
- Listen for weird squeaks, hums, whistles and gushing water noise that indicate a broken or missing drip emitter.
- Look for hard water buildup which can reduce water volume. Clean off or replace the emitter.
- Replace the broken emitter with an exact match.
- Join torn or broken drip pipes with connector pieces.
- Check that the supply tubing ends are closed to allow the system to build pressure.
- Adjust the drip system to deliver water where your plants need it now vs. when they were planted. Be sure to apply water to the entire root area. Mature plants may need another drip head or two added for adequate irrigation.
Add additional drip heads as needed for maturing landscape. Consult your irrigation design and manufacturer for the number of drip heads each zone can support. - Remove drip lines and heads in areas where they are no longer needed. It's easy to install a plug in the supply tubing.
Garden Hose and Watering Cans
If you water with a hose and watering can, don't let your trusty garden friends let you down when you most need them!
- Fully unreel your hose and inspect it for holes and cracks, smooth out hose kinks if you can and inspect bulging sides for failure. Repair or replace as needed.
- Replace hose rings at the faucet to get a tight drip-free fit.
- Replace hose rings in watering tools - wands, spray heads to keep the flow strong.
- Clean debris from watering can, inspect for holes, clogged spout and sprinkler head.
With this checklist, you have likely identified a few adjustments to your system before the temperatures soar. Continue to monitor your system for problems and make timely repairs for the best health of your garden and to avoid a surprisingly large water bill.
Resources
- Irrigating fruit and shade trees and shrubs
- Watering calculators from the Center for Landscape Urban Horticulture.
- UC Guide to Healthy Lawns
- Cultural tips for trees, shrubs and woody plants
- EBMUD Lawn and Landscape Watering Schedule (opens a pdf document)
Have a gardening question?
We'll help. You can reach us by:
- Emailing acmg@ucanr.edu. Please include a photo of the problem, if you can, plus your name, phone number, city and a description of the problem.
- Using our online form.
- By phone, during our office hours, 10 am to noon Wednesday and 11 am to 1 pm Thursday: 510-670-5645. At other times, please leave a message and we'll return your call during our office hours.
- In person at our Hayward office, during our office hours, only by appointment.