- Author: Help Desk Team
Note: We are running this previously published article because it's important to be ready to protect sensitive plants. Don't get taken by surprise!
It's time to get ready for cold winter temperatures and to start preparing protection for citrus trees and other frost-sensitive plants. Depending on where you live in Contra Costa County, your first frost date may be as early as Halloween. However, November 15 is often thought of as a first frost date in much of our County, with slightly earlier in the eastern portion and later in the more temperate West County areas. Because significant climate variation can occur, it's good to start thinking of frost protection early, before you need it.
Frost can start to occur when the temperature gets below 36°F and is sure to happen at 32°F. When temperatures drop below 32°F, it becomes a freeze, and if it drops below 28°F, it's a hard freeze.
Protecting plants when temperatures drop in the Bay Area can be done using three simple elements:
Water: It may seem counter intuitive, but water can provide protection from freezing temperatures. When dry soil freezes, moisture is pulled from the roots, causing damage. If the soil is moist, it can freeze without harming roots. Wet soil also holds more heat than dry soil. When the forecast calls for 32°F or below at night, water the ground around your plants lightly in the late afternoon or early evening. The exceptions to watering plants before frosty temperatures are succulents. They need to be kept dry when a freeze is expected if you can't move them into a warmer spot.
Frost Covers: Protect tender plants and trees with frost covers either purchased or homemade. Sheets, blankets, tarps, or burlap can be used, but these need to be propped up above the leaves and removed in the morning. These materials can become wet with dew and damage sensitive leaves. Commercial frost cloth comes in several weights and can provide up to 4°F protection (find it at your local nursery or home and garden store). It can float over the top of the plants and can be left on for several days since light can pass through it. For very sensitive plants, make sure the cover goes all the way to the ground. If very cold temperatures are forecast, also wrap the trunk of a young citrus tree with cardboard to protect the bud union and above.
Covering or tenting should be done in the late afternoon or early evening when freezing temperatures are predicted, then removed in the morning after frost has thawed to allow for healthy air circulation and to allow the soil to warm in the sun.
Heat: Moving potted plants indoors, into a greenhouse, or even grouping them together under a tree or house eaves to conserve heat will give enough protection for many plants. A light bulb (100-watt designed for outdoor use) or Christmas lights (old-fashioned incandescent type lights—LED lights do not emit enough heat to help) under a frost cover can add additional heat. Make sure you use extension cords and lights rated for outdoor use.
If plants have suffered damage from frost, wait to prune until spring. Frost-damaged areas on plants can add protection to parts below if there is another freeze. You also don't want to stimulate the plant to put out new tender growth that would surely be damaged in another frost.
Following is a link to a UC publication titled Frost Protection for Citrus and Other Subtropicals: https://anrcatalog.ucanr.edu/pdf/8100.pdf
Help Desk of University of California Master Gardener Program of Contra Costa County (SEH)
- Author: Help Desk Team
Halloween creeping up on you? Well, the UC Master Gardeners have got some boo for you!
Mother nature seems to enjoy providing us with ‘deviant' forms of plants that are strangely shaped and, as a result, we field lots of questions from the public about the peculiar growth of plants in their gardens (especially fruits and vegetables). These questions often arise to make sure that these oddities are safe to eat. Some plant mutations do look a bit alien and maybe even a little possessed, so it's a good idea to be sure they're safe! The good news is that while scary, many of these deviant forms are often perfectly okay to consume (after snapping a photo or two for posterity, of course!).
Two types of abnormal growth that are commonly seen in plants are called fasciation and monstrosity. Fasciation, which can be seen in a variety of plants, including succulents, occurs when normal stems turn into a wedge, fan, or crest. This can lead to plants that are very unlike their parent with smaller leaves, more ribs, altered branching and even suppressed flowers.
Monstrous growth is even more difficult for the plant to deal with. In these cases, it's as though the plant can't decide where to grow from and creates growing points all over the place. Monstrous growth produces all sorts of strange forms.
Another mutation is variegation. In plants, variegation means the appearance of different colored zones on leaves, stems, fruit or flowers. Variegations can be uniform (sometimes called pattern-gene or natural) – this is where the variegations occur in the same way across an entire plant. Variegations can also be random (known as ‘chimeral'). Virus infections can also cause the natural variegation of plants.
As a general rule, mutant forms are weaker growers than their normal forms. They need greater protection from the full sun and they are subject to the same insect pests as other plants though they tend to have more difficulty dealing with them.
Mutations tend to be random and are the result of a change within the cells of the plant, but some mutations can be triggered by environmental conditions such as cold weather, temperature fluctuations, or insect damage. Inadequate pollination may cause sections of a fruit or vegetable not to develop seeds, cease to grow, and impact the shape of the fruit and vegetables. Luckily for us, weirdly shaped vegetables and fruits have the same nutritional value as the normies and are just as tasty.
We've all seen oddly shaped fruits and vegetables such as carrots with legs, crazy-looking strawberries, and eggplants with noses, as well as many other odd shapes that are perfectly normal in some fruits. If you haven't seen any of these monsters, take a look at the photos below!
Wait until this Buddha's Hand Citron gets larger and turns bright yellow! Terrifying!
This is ‘normal' behavior for this Tomato, Phil's One! What in the world?
This odd behavior occurs in strawberries when the seeds try to germinate before they detach from the plant. This may have been caused by environmental stressors such as cold temperatures. The strawberries are safe to eat!
The deformity of this tomato mainly results from abiotic disorders. Abiotic disorders are plant problems caused by too much or too little water, nutritional deficiencies, too much sun and sometimes just common growth in some varieties of indeterminate tomatoes!
What in the world is wrong with this eggplant? A common, yet hard to explain behavior!
This zucchini was found at Our Garden in Walnut Creek in 2021. We believe that this is called everted ovaries and may have been caused by lack of full pollination, a virus, or even spontaneous genetic mutation!
There are so many weird and wonderful plants you can grow in your own garden such as: Romanesco Broccoli, Black Carrots, Dragonfruit, Bitter Melons, Black Tomatoes, Tomato Phil's One, Buddha's Hand Citron, and Jerusalem Artichokes. Check out your local nurseries or seed providers for many monstrous ideas!
Have no fear… Many of the plants we covet in our gardens are actually created by mutations! Thank you, Mother Nature!
Happy Halloween!
Help Desk of the UC Master Gardeners of Contra Costa County (SLH)
- Author: Help Desk Team
The Mediterranean climate of Contra Costa County has us spoiled for choices in growing handsome perennials and shrubs, including many native plants that attract local beneficial insects and nourish our ecosystems. Whether you are planning a new garden or adding to an existing one, references abound to help you select and plant perennials successfully.
September through Thanksgiving is the best time to plant most perennials and shrubs, especially California natives. The soil is still warm enough to encourage good root development and most importantly, cool weather and winter rains get plants off to a good start. Make sure you water them well when first planted, then continue watering until winter rains start.
Plants adapted to a Mediterranean climate need moisture until their root systems mature (with some succulents being exceptions). These plants may still need water during the summer to look their best but will tolerate a long dry summer much better with well-developed roots.
“Drought-tolerant” is a somewhat misleading term. Several dry months during our typical Mediterranean summers do not result in a drought. “Climate-adapted” or “water-smart” are more helpful terms to describe plants. These are adapted to the normally dry summers and wet winters common in many Mediterranean areas. Water conservation during any California summer makes economic and ecological sense.
Some reliable favorites include Toyon (Heteromeles arbutifolia), Sunset Manzanita (neat and tidy), De la Mina Verbena (Verbena lilacina 'De La Mina'), Salvia ‘Bee's Bliss' (needs room), Flowering Currant (Ribes sanguineum), Epilobium, Yarrow, and California Buckwheat. Check the Native Plant database listed below to see which plants will do well in your zip code or in a particular spot in your garden.
The first four references below are robust websites to help you select perennials that will work in Contra Costa County. We are biased toward water-wise California natives, although perennials from other Mediterranean climates can do well here. If you have a lot of garden space, you may want the help of a professional landscaper (see last reference).
• East Bay MUD water-smart plants (natives and non-natives): https://www.ebmud.com/water/conservation-and-rebates/watersmart-gardener/watersmart-plants
• UC Davis “All Star” Plant Database (natives and non-natives): https://arboretum.ucdavis.edu/plant-database
• Contra Costa County water-saving plant database (natives and non-natives): https://www.contracosta.watersavingplants.com/search.php
• Native plant database from California Native Plant Society: https://www.calscape.org/
• How to find a landscape professional https://rescape.memberclicks.net/directory
Help Desk of the UC Master Gardeners of Contra Costa County (EAS)
- Author: Help Desk Team
Irrigation is not a ‘set and forget' thing. Your watering schedule should be adjusted each season (at least four times each year) as water needs in the landscape vary greatly from season to season. Seasonal adjustments allow us to adapt to changing weather conditions, plant growth patterns, and water availability. If your irrigation system isn't adjusted with the seasons, your plants can suffer from overwatering in the winter or underwatering in the summer.
As seasons change through the year, your plants' needs will change, too. For example, a 15-foot wide Chinese pistache tree (Pistacia chinensis) growing in Concord needs 52 gallons of water each week in July, 24 gallons per week in October, and only 8 gallons each week in January. Adjusting irrigation according to the season can decrease water use by half and your plants will be healthier.
You can calculate how much water your landscape should have for best growth. Look up the water needs of your plants in this database: https://ccuh.ucdavis.edu/wucols-db. Determine how much water is needed for each of your plants throughout the year here: https://puddle-stompers.com/waterwonk/how-much/index.php
Even knowing what your plants ‘should' need, it's best to test your soil occasionally to make sure the water you apply is getting to the right place. To test the depth of your watering, use a soil sampling tube or a small trowel to dig down 6–8 inches deep and observe the moisture level at the bottom of the hole. Get your hands dirty and learn what your soil feels like with varying moisture levels.
There can be substantial water waste when automatic watering systems are left to run on their own. Some systems come with a rain sensor function that will automatically turn off the system when it rains and others are smart controllers that adjust the schedule based on environmental factors. It might be time to upgrade your controller to take advantage of these benefits.
Some additional reminders for good irrigation practices:
Apply the right amount of water
Overwatering is more common than underwatering and can lead to more disease problems.
Water plants deeply and infrequently
The entire root zone should receive water, but let the soil dry partially in between to reduce the chance of root rot and other diseases.
Water early in the morning
Cooler temperatures and less wind will reduce evaporation, especially if using sprinklers or above-ground systems.
Avoid runoff
This happens often in clay soil and the water is simply wasted. Cycle the irrigation giving enough time for each cycle to be absorbed.
Regularly maintain your irrigation system
Check for leaks or damaged parts that could be wasting water and preventing water from getting to the right place.
Apply mulch
A 2- to 4-inch layer will reduce evaporation, minimize weed competition, and improve the soil.
See these links for more information on irrigation:
https://sonomamg.ucanr.edu/Drip_Irrigation/Drip_Irrigation_in_Different_Landscape_Situations/
https://sonomamg.ucanr.edu/Drip_Irrigation/
Help Desk of the UC Master Gardeners of Contra Costa County
- Author: Help Desk Team
Q: Can I use the graywater from my washing machine to water my vegetable garden and fruit trees?
A: There are two key considerations, discussed below, relating to the use of graywater in the garden: what is meant by the term graywater and on what plants to use it.
Graywater Definition
Graywater is untreated, non-disinfected household wastewater that does not include toilet waste. It may be sourced from showers, baths, and washing machines. Untreated water from sources such as kitchen sinks and dishwashers, which may have properties that encourage pathogens, is called dark graywater. Water from toilets and washing machines used to launder diapers or chemically contaminated clothing is called black water. Only graywater should be used in the landscape.
Graywater Usage
Graywater can be safely used to water landscape plants and orchard trees. Because graywater can contain bacteria and viruses that cause illness, it should not be used to grow vegetables if the edible portion may come in contact with the soil. For example, graywater should not be used for growing asparagus, beets, carrots, cucumbers, lettuces and other salad greens, garlic, onions, potatoes, melons, squash, bush beans, radishes, turnips, unstaked tomatoes, or strawberries. Crops not touching the ground like staked tomatoes, peppers, and eggplants should be OK.
https://ccmg.ucanr.edu/files/289340.pdf
Laundry Detergent Considerations
When using laundry rinse water to irrigate plants, your choice of household products will affect the composition of the graywater. The wrong products can adversely affect plants and soils. It is best to avoid using products that contain sodium or sodium compounds, bleach, or boron, as these can result in an alkaline soil condition that suppresses healthy soil biologic activity and is poorly tolerated by many plants.
Although the UC Master Gardener Program of Contra Costa County cannot recommend any products, the FAQ page on Greywater Action's website (https://greywateraction.org/greywater-faq/) lists some products that are plant friendly. These are generally biodegradable, non-toxic, and salt and boron free. The Ecology Center in Berkeley has also evaluated several cleaning products for compatibility with graywater systems. Consult their website at https://ecologycenter.org/factsheets/ for a current list of products. (Click on the link to Greywater-Compatible Cleaning Products.)
Other Considerations
Some key takeaways excerpted from our Marin Master Gardener colleagues are listed below. https://marinmg.ucanr.edu/BASICS/CONSERVE_WATER_-_ENERGY/Graywater/
Do:
Water ornamentals with graywater which is often rich in nutrients.
Check your plants first—Acid-loving plants won't tolerate salts found in high pH graywater and evergreen trees are often more salt-sensitive than deciduous trees.
Alternate graywater irrigation with fresh water to minimize salt build up.
Watch what you put in the wash. Use biodegradable pH balanced, sodium-free, boron-free, chlorine-free products in the washing machine and for bathing.
Apply graywater directly to the ground—don't allow it to be sprayed on plant surfaces.
Use graywater within 24 hours after collecting to minimize bacterial growth.
Don't:
Don't let graywater come in contact with skin.
Don't use on root vegetables such as carrots and onions.
Don't use on lawns unless the graywater is delivered below the surface. If sprayed on the surface, people or pets may come in contact with it.
I hope this helps. Please don't hesitate to contact us with any further questions. Good luck with your tomatoes and fruit trees!
Help Desk of the UC Master Gardeners of Contra Costa County (GD)
