By Michael-Anne Foley, Butte County Master Gardener, May 17, 2013
Are you confused by plant catalogues or magazine articles using different climate zone maps to describe the appropriate environment for particular plants? You are not alone.
The two primary climate zone maps used in the United States are the USDA plant hardiness zones and the Sunset zone guide. Most (but not all) mail-order plant catalogs indicate the appropriate USDA zones for their plants, while many nurseries in the West use the Sunset system. Since nurseries often source at least some of their plants from big commercial growers, at the same nursery you might find some plants labeled with their USDA hardiness zones, and others labeled with their Sunset zones. It is not surprising, then, that people often find the whole subject of plant-appropriate climate zones confusing.
The USDA plant hardiness map divides North America into 11 hardiness zones. Zone 1 is the coldest; zone 11 is the warmest. When you order plants from catalogs or read general garden books, you need to know your USDA zone in order to be able to interpret references correctly.
The 2012 USDA Plant Hardiness Zone Map compiled by the USDA and Oregon State University is based on the annual average minimum winter temperature over a 30-year period, and is divided into zones of 10 degrees each, further sub-divided into “a” and “b” zones of 5 degrees. Since 1990, the zone boundaries have shifted in many areas. Zones on this new 2012 map are generally 5 degrees Fahrenheit (a half zone) warmer than those indicated on the previous map. This data was accumulated over the 30-year period before 2005; the new zone map based on this information was released in January of 2012.
Now, for the first time, the USDA map is available as an interactive GIS-based map, for which a broadband Internet connection is recommended, and also as static images for those with slower Internet access. Users may also simply type in a ZIP Code and find the hardiness zone for that area. For example, using the USDA Hardiness Zone map, Chico, Oroville and Paradise are all located within Zone 9a (minimum winter temperatures of 20-25 degrees Fahrenheit). Although this is a useful plant hardiness index it has some important drawbacks: for example, it puts the Olympic rain forest into a zone with parts of the Sonoran Desert.
Gardeners in the western United States are sometimes confused when confronted with these 11 Hardiness Zones created by the USDA. A more useful index is the 24-zone climate system published in the Sunset Western Garden Book in collaboration with the University of California. The Sunset climate zone map for gardening was devised in the mid-20th century for thirteen western states. It has been expanded to include areas across the U.S., providing a more useful alternative to the USDA zone system.
The 24 Sunset Zones are determined by a number of factors to help gardeners identify the most appropriate plants for their needs. Winter and summer highs and lows are used to provide information about the temperature extremes in the region. Weather patterns like humidity, rainfall and heat are considered. The Sunset Zones also take into account specific environmental conditions like prevailing winds, day length and soil type.
The greater precision of the Sunset system is evident in our local area: Chico is in Sunset zone 8, Paradise is in Sunset zone 7, and Oroville is in Sunset zone 9. Because the Sunset zone maps are more precise than the USDA’s, they are considered the standard references for gardeners in the West. So, when you purchase plants for your zone, be sure you are using the right zone map! Sunset’s zones 7 and 8 are much warmer than the USDA zones 7 and 8; mixing up the systems might well result in planting the wrong plant in the wrong place.
And keep in mind that even within a city, a neighborhood, or a street, microclimates can affect how plants grow. For example, planting tender citrus against a wall that absorbs daytime heat places it in a micro-climate that is warmer than a more exposed area. The zones are a guide and a good starting point, but you still need to determine for yourself what will and won't work in your garden.
Resources:
http://planthardiness.ars.usda.gov/PHZMWeb/
http://www.sunset.com/garden/climate-zones/sunset-climate-zone-northern-california-00418000067169/
http://ucanr.edu/sites/gardenweb/Your_Climate_Zone/
By Ken Hodge, Randy Swett, and Eve Werner, Butte County Master Gardeners, May 3, 2013
Tomatoes are possibly the most popular summer vegetable for home gardeners to grow. Although tomatoes are technically fruit (the fruit of the tomato plant), they are used as vegetables in cooking, and many would agree that they are indispensable as savory ingredients in food, no matter how they are classified. The real problem lies in selecting which tomatoes to grow since there are so many different varieties available.
If you haven’t grown tomatoes before, the best way to start is to narrow down the possibilities by determining the uses for your tomatoes: slicing tomatoes are used on sandwiches and hamburgers; small, sweet cherry-sized tomatoes are perfect for salads and immediate gratification right off the vine; spicier-tasting tomatoes add a kick to salsa; paste tomatoes are best for canning and cooking because they have fewer seeds and less juice; and some varieties are well-suited for sun-drying.
Good slicing tomatoes that do well in our climate include the Beaverlodge Slicer, Aussie, Dinner Plate, Giant Belgium, Aunt Ginney's Purple, Marianna' Peace, Good Old Fashion Red, Momotaro, and Rainbow. Cherry tomatoes include Sugar Lump, Isis Candy, Sun Gold, Black Cherry and White Currant, in addition to the more commonly sold (but nonetheless delicious) Sweet Million and Hundred Million. La Roma & San Marzano make great salsa & are good for shish kebabs. Amish Paste, Costoluto Genovese, San Marzano Ridorta and Red Pear make excellent tomato sauce. Some of the lesser known, interesting & tasty large tomatoes are Pineapple, Marianna's Peace, Kellogg's Breakfast & Brandywine. Pachino & Princepe Borghese are good for making sun-dried tomatoes.
Another characteristic that may influence your choice of tomato plants is whether they are determinate or indeterminate. A determinate tomato plant stops growing when it sets fruit. Their compact size and bushy growth make determinate tomatoes good choices for containers & small space gardening. And if you plan on canning or freezing tomatoes for later use, determinates will be most convenient because they ripen all their fruit at once in a relatively short period. Good examples of determinate tomatoes are La Roma and Beaverlodge Slicer.
Indeterminate tomato varieties (also known as “vining” tomatoes) grow, bloom, and produce fruit continuously until killed by frost, providing a steady supply of ripe fruit throughout the season. With indeterminate tomatoes you will see blossoms, green tomatoes, and ripe tomatoes commingling on a single plant. Indeterminate varieties grow big – six to ten feet tall in the Sacramento Valley. For example, the aforementioned White Currant cherry tomato grows rapidly and spreads extensively in ideal (sunny) conditions. But indeterminate plants can be pruned and staked or caged to control their size and shape. Sturdy supports with wire mesh cylinders or panels will promote healthy growth and reduce damage from pests and sunburn. Don’t prune a determinate tomato much or your harvest will be reduced.
Most tomatoes are indeterminate, especially the interesting heirloom tomatoes which have become more available in the past few years. The strict lines between determinate and indeterminate may become looser with advances in plant breeding (just as the distinctions between floribunda and hybrid tea roses have become less defined). For example, Celebrity is considered a semi-determinate tomato, because it ripens over a broader season than true determinate tomatoes.
There are many tomato varieties to choose from: selecting tomatoes best suited to your eating plans will enhance your gardening (and dining) experience.
Photo: San Marzano Tomatoes
By Cindy Weiner, Butte County Master Gardener, April 12, 2013
Have you ever felt overwhelmed by the selection of plants at the nursery? Or bought a plant that looked great at the nursery, but did poorly (or died) in your yard? Spring is here and it’s tempting to rush out and buy new plants for the garden. But don’t be too hasty! Choosing the right plant for a particular location requires some homework. The time you spend beforehand will pay off by greatly reducing plant "failures."
First, consider the function you want the plant to perform in the garden. Do you want it to provide shade or act as a windbreak or hedge? Will it be a focal point? Would you like colorful flowers? These decisions help narrow your choices at the nursery.
Next, consider the environment of the site. Many factors in your yard affect how a plant grows. Is the soil heavy or does it drain quickly? Is the site in full sun or shaded? Does it get blazing afternoon sun? Is it exposed to reflected heat from a patio or wall? How much water will it get from existing (or planned) irrigation?
When selecting a plant, carefully consider the specifics of the site. Look at the plants growing nearby and think about how you want the new plant to blend in, in terms of size, color and texture. Will the plant be under power lines or by a fence or pool? These elements can affect your plant choice. Tall shrubs or small trees planted under power lines will require frequent pruning. A large plant can grow into your neighbor's space or drop litter into a pool.
After thoroughly analyzing the planting site, think about the characteristics of the desired plant. Do you want a tree, a shrub, a low-growing perennial, or simply annual color? Evergreen or deciduous? What height and width should it be at maturity? You don't want it to outgrow the available space. What water requirements should it have to match the surrounding plants? It's much easier to plan appropriate irrigation to keep plants healthy if plants growing in the same area have the same water needs.
There will still be a large number of possible choices, so you'll need to narrow your selection more. Consider choosing natives or other plants with lower water needs, since they are well adapted to our climate, and many attract beneficial insects. Talk to your neighbors, and look at their garden successes. Call the Master Gardener hotline for advice (530-538-7201.) Visit a nursery to look at their plants, examine the labels, and ask employees for suggestions. The labels have information about eventual plant size and temperature tolerances.
Check to make sure the plant is suitable for our climate. Choose plants appropriate for your USDA Hardiness Zone (these are based on winter minimum temperatures in an area) OR refer to the Sunset Western Garden Book's plant climate zones, which also take other factors, such as heat, humidity, wind, and length of the growing season, into consideration. In Sunset's system, Paradise is in Zone 7, Chico and the valley floor are in Zone 8, and the Oroville foothills are in Zone 9. There are gardening books and online sources with good plant suggestions for these zones. The Sunset Western Garden Book describes 9000 plants that grow in the West and also has lists of appropriate plants for specific situations. The UC Davis Arboretum publishes a list of 100 Arboretum All-Stars, easy-to-grow plants that do well in our valley climate. Arboretum All-Stars can be found at:
http://arboretum.ucdavis.edu/arboretum_all_stars.aspx
Doing your homework to choose the right plant will improve survival and make your plant selections more satisfying.
By Jeanette Alosi, Butte County Master Gardener. March 15, 2013
Have you noticed yellowing leaves on clumps of foliage on one or more of your plants lately? If so, scales may be responsible for the damage.
Scales are insects that suck plant fluids by inserting a tiny straw-like mouthpart into various parts of a plant. Scales are very small, and when they are doing their damage (in the larval stage) they are wingless and have no distinguishable body parts. Unlike aphids, for example, scales are slow moving or immobile.
The damage of a scale infestation depends upon the type of scale, the species of plant, environmental factors, and the proximity and numbers of natural enemies.
The two common scale families are soft and armored scales. Soft scales may be smooth, cottony, or waxy. They are usually about one-eighth to one-quarter-inch in diameter, and round to oval in shape. They feed on fluid-conducting phloem plant tissue and excrete honeydew. Common soft scales are black scale, brown soft scale, cottony cushion scale, and European fruit lecanium scale.
Armored scales are tinier than soft scales (less than one-eighth-inch) with a flattened, removable scale cover. They do not excrete honeydew. Common armored scales include California red scale (on citrus) and San Jose scale.
There are many other species of scales and scale look-alikes. It is important to identify the scale family in order to determine the most effective control methods.
Most female scales produce eggs without mating. The eggs hatch into crawlers (also known as first instar nymphs). Crawlers, about the size of a typed period, are usually pale yellow to orange. After a few days, they establish themselves on a nearby feeding site and rarely move again. Once they become firmly attached to a feeding site, scales will grow through several larval stages during their lifetime (although their appearance will not radically change) before becoming adults. Most soft scales produce one generation a year. Armored scales produce several generations a year.
Scale damage is dependent upon the level of infestation. In addition to yellowing leaves, plants affected by scales may experience premature leaf drop and discolored blemishes on fruit, leaves or twigs. If heavily infested with armored scales, twig dieback may also occur. The main problem with soft scales is the secretion of sugary honeydew which attracts ants and encourages the growth of black sooty mold. Soft scales rarely kill trees and shrubs but can reduce plant vigor, while recurrent infestations of armored scales can cause twig and branch dieback.
In most cases, scales are controlled by natural enemies, especially parasitic wasps. A parasitized scale will appear darker than normal. Other natural enemies include lady beetles (“lady bugs”), lacewings and mites. Because ants feed on the honeydew secreted by scales, they will protect the scales from their natural enemies. Controlling ants will therefore help to decrease the scale population. Beware of using broad-based insecticides because they kill beneficial insects and scale parasites indiscriminately, as well as the scales and ants.
Cultural practices to control scales include pruning to improve air movement and light penetration into dense canopies, and selection of plants that are less prone to scale infestation. Because scales tend to be host-specific, replace problem plants with plants less attractive to scales. Planting flowering plants near scale infestations will aid in attracting natural enemies.
For limited scale infestations, prune out heavily infested branches. Pruning to open up the tree canopy will expose scales to the hot sun, increasing their mortality.
Heavy infestations may require the use of horticultural oil during the dormant season or when the crawlers (nymphs) are active during the growing season (late winter to early summer). Read the label carefully when mixing with water, as horticultural oils may damage plants under certain conditions. To smother (and destroy) the scales, affected areas including the undersides of leaves must be thoroughly coated with the horticultural oil spray. On larger ornamental shade trees (non-fruit-bearing), a soil-applied systemic insecticide might be considered.
For more information, see “Scales, Pest Notes Publication 7408,” at
http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7408.html
Photo: San Jose scale on peach branch
/span>By David Walther, Butte County Master Gardener, March 1, 2013
Early spring is the perfect time to apply mulch to your garden. Mulch is any material that covers the ground and insulates it from sun, evaporation, and erosion. After you have finished your winter cleanup and pruning chores, but before the rains end is a great time to mulch, not only to provide the best environment for your plants, but also to help prevent the growth and development of weeds.
Mulch is good for the soil, and thus good for your plants for a number of reasons. It jump-starts the useful work done by microscopic organisms (this is often referred to as microbial activity); retains moisture, thus preventing plants’ roots from drying out; and deters weeds by providing a barrier between the soil and the sun.
Mulching is also a time-saver for the gardener – it takes a fraction of the time to put down mulch that it would take to weed later on. And using mulch to control weeds reduces the use of expensive herbicides.
Mulch can be composed of organic or inorganic materials. Organic mulches include manure, compost, grass clippings, shredded bark, shredded wood, and even newspaper sheets (more attractive when covered with compost so the newspaper doesn’t show). Pine needles can be used as mulch but they are very flammable, so it is best to chop or grind them up first. Shredded leaves from fall leaf drop make excellent mulch.
Natural inorganic mulches include gravel, pebbles, and crushed stone. Other inorganic mulches are plastic, cardboard, and even pieces of old carpet. The mulch you use will depend upon the job you want the mulch to perform and how you want it to look.
Any ground that needs enrichment, such as flower or vegetable beds you will be planting later in the season, will benefit from an application of organic mulch. Mulching around shrubs, trees, annuals, and perennials will improve the soil that feeds their roots, as well as deter weeds. Large areas that you wish to keep weed-free are also candidates for a thick application of mulch.
Pile mulch six to eight inches deep, tapering down to three inches deep about 10 inches away from the stems or crowns of plants. Do not place mulch directly on top of plant crowns or too close to the trunk or stems of your plants, since a layer of mulch can cause the crown to rot. You can, however, apply mulch right on top of plants that do not have above-ground stems or crowns (such as bulbs, stoloniferous or rhizomatous plants).
To control annual weeds, apply four to six inches of mulch on top of the soil, or even on top of the weeds themselves. To control perennial weeds, an application of 12 to 16 inches of mulch is needed.
The reappearance of weeds in an area that has been mulched is an indication that the mulch has decomposed to such a degree that a new application of mulch is required.
While the benefits of applying mulch are many, mulch can also lead to an increase in mole activity because of the increase in the worms and grubs they feed on – the more alive your soil is, the more it becomes a habitat for other creatures.
Mulch can deplete the soil of nitrogen during the process of decomposition, so it is a good idea to supplement occasionally with applications of fertilizers rich in nitrogen such as manure, bloodmeal, feather meal (made from chicken feathers), or cottonseed meal.
Finally, different garden situations require different choices of mulching materials: for example, dryland garden plants (xeriscape plants) such as native California plants, cacti, and succulents, have evolved to flourish in dry conditions and poor soil. The moisture-retentive qualities of organic mulch could be detrimental to their vigor and growth while the use of stone or gravel mulch would be helpful in replicating their natural environment.
Your mulch choices can range from commercial mulches purchased at a landscape center, to bags of organic mulch available at nurseries and home improvement stores, to your own (free!) shredded leaves, grass clippings, and yesterday’s paper. The benefits of mulching far outweigh any negatives, so there is no reason not to mulch.