- Author: Help Desk Team
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
Garlic has been part of agriculture for at least 5000 years and is thought to have been brought to the Americas by Columbus. There is much folklore associated with it, from treating warts to fighting off vampires! Garlic, leeks, and shallots are members of the onion family (alliums) and are great cool-weather crops for winter gardens in our area. They are easy to grow and do not take up a great deal of garden space.
Growing conditions are similar for most members of the Allium family. They need reasonably fertile soils (amend with compost), but must have good drainage as bulbs may rot in soggy soils. They also like a sunny spot. The links given below each variety give more information on how to grow them.
Garlic
Garlic is best planted in October or November and will be ready to harvest in June or July. It is started from ‘seed garlic', individual cloves separated from a garlic bulb. Good quality disease-free seed garlic from a nursery should be used, rather than grocery-store garlic. You can also use bulbs saved from last year's crop. There are many different varieties of garlic, with varying degrees of flavor and spiciness.
These fall into two main types: Softnecks are the ones found in grocery stores and have a flexible stem which can be incorporated into braids. California Late White and Early White are examples of softneck garlic. They store well. Hardnecks or Rocambole tend to have larger cloves and more flavor variations. They have a stiff central stem between the cloves, hence the name! They are better suited to a colder climate than ours in the Bay Area, and do not store as long as softneck garlic. Nonetheless, many of us grow hardneck garlic successfully.
http://ipm.ucanr.edu/home-and-landscape/onions-and-garlic/cultural-tips/
https://vric.ucdavis.edu/veg_info/garlicprodtips.htm
https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=43862
Elephant Garlic
This looks like a giant garlic bulb but is actually closely related to leeks. It has a milder flavor, with big flower heads and foliage reaching to 4 feet tall. Fun to grow with kids!
Shallots
Shallots are mild-tasting onion relatives and are much-used in gourmet cooking! They can be grown from seed, but often the individual bulbs are planted in a similar fashion to garlic and will form a new cluster as they grow. Drainage is especially important for shallots, as the bulbs will rot if they remain too wet. https://ucanr.edu/sites/mgscc2016/files/333041.pdf
Leeks
Leeks may be planted from seed, but also seedlings can be very economically purchased from a nursery. Leeks like regular water, but as with their relatives, good drainage is essential. They are often planted in a trench with soil being gradually added as they grow to create the blanched stems usually associated with leeks.
https://sonomamg.ucanr.edu/Vegetable_of_the_Month/Leeks/
Conclusion
Growing alliums in winter is a great way to keep your garden producing during the cooler months. If we end up having a good rainy season, these plants will be watered with free water. If not, keep watering during the dry spells so the plants continue to grow.
Help Desk of University of California Master Gardener Program of Contra Costa County (SMW)
- Author: Help Desk Team
For most of the Bay Area we had an unexpected but wonderful seasonal surprise – RAIN. This blessing provided a drink of water to plants that we have had to ignore due to water rationing.
We were not the only ones waiting for that first seasonal rain. Subterranean termites were waiting for that cue to emerge from the soil and party. Winged reproductives leave the underground nest in swarms to seek out a mate and then search for a new nest site. You may have seen them flying in swarms or on the ground exiting or landing on the soil.
They generally fly less than 300 feet from their emergence point. Their goal may be thwarted though, as this ritual exposes them to predation by birds, reptiles, spiders, and other insects. Most of the reproductives don't survive the feeding frenzy.
The most common subterranean termites, Reticulitermes, can be encountered in nearly all regions of the state. It can swarm in fall or spring and both situations are warm days following rain. They are not very big, less than one-half inch long including the wings, which are silvery-gray and twice the length of the body itself.
When not involved in the mating ritual, they live in the soil. Subterranean termites require a moist environment, and living in the soil and feeding in dead and decaying wood meets that need.
Termites are decomposers which benefit the environment. Unfortunately for us, dead wood includes structural lumber of which our homes or outdoor structures are made.
Since most soil around a home has buried wood debris (roots, stumps, or fence posts), finding swarming termites in your yard doesn't necessarily mean your house is infested. If you see a swarm on your property, do you have a problem? Possibly.
Andrew Sutherland, University of California's Urban Integrated Pest Management Advisor for the Bay Area, wrote in his blog: “If observing a swarm on your property, especially if near your home or other structures, you can hire a professional termite company for a detailed inspection. Make sure to photograph or otherwise note the swarm location so that the inspector can start there.”
If you would like additional information on subterranean termites, including recognizing their activity in and around the home and management options, check out the following link to UC IPM's Pest Note titled Subterranean and Other Termites.
http://ipm.ucanr.edu/PMG/PESTNOTES/pn7415.html
Help Desk of University of California Master Gardener Program of Contra Costa County (EDC)
- Author: Help Desk Team
What is a cover crop? It's a crop grown to feed and protect the soil when the garden is not being used for active food production. Cover crops can transfer nitrogen into the soil, provide large amounts of organic matter, act as a mulch to prevent erosion, improve soil structure, promote water infiltration and retention, suppress weeds, and stimulate beneficial microbial soil life. That's impressive for a small packet of seeds. And they can be beautiful and attract beneficial insects and pollinators.
What kinds of plants can be used for cover crops and what roles do they play?
- Legumes have unique relationships with soil bacteria, allowing the plant to transfer, or fix, nitrogen from the air into the soil. In addition, they produce hefty biomass (green, leafy material). This can be cut down and used as mulch, it can be turned into the soil to act as a green manure (decomposing in place), or it can be used as a compost crop and added to the compost pile as a nitrogen source.
- Grains and grasses have a different relationship with the soil because of their deep root systems. The action of the roots loosens and aerates the soil, providing channels for air circulation and water flow. Grain plants tend to be tall which results in an abundance of biomass for mulch, green manure, or material for compost.
- Broadleaf plants are used as cover crops for their rapid growth and big leaves. They establish quickly, shade out weeds, prevent erosion from water and/or wind, and generate heaps of biomass for mulch, green manure, or compost material.
- Check this link to see the UC ANR Cover Crop Database where you can find information on a variety of cover crop plants: https://sarep.ucdavis.edu/covercrop
Purchase cover crop seed from a local nursery or from an on-line seed company. If you decide to grow a legume cover crop, it is recommended that you buy “inoculant” powder at the same time you purchase your seeds. The inoculant is a natural bacterium that helps the legumes with the nitrogen conversion. When you're ready to plant (September or October is good), put some inoculant powder on a plate. Wet the seeds and roll them around in the powder.
Evenly broadcast seeds over the area you want to cover. You can make neat rows, or you can spread the seeds over the entire area. Cover the seeds with soil from ½ inch to 1½ inches deep depending on the size of the seeds. Keep the soil moist for the first week to aid with germination and then water as needed when the soil dries.
To get the maximum amount of nitrogen from a legume crop, cut or mow it after it starts flowering in the spring, allowing several weeks for the mass to decompose before planting something else. For other types of cover crops, cut them before they go to seed, or several weeks before you want to plant your crops.
Is it worth the effort to grow plants you're not going to eat? You bet it is! Deciding to grow a cover crop will be one of the best decisions you make for your soil's health and overall vegetable production. Cover crops will save you time, energy, and money and we can all use more of each of these.
Sources and Resources:
- This link will give you planting instructions and harvesting guidelines: https://marinmg.ucanr.edu/EDIBLES/COVERCROPSETC/
- The following suppliers are good sources for cover crop seeds
- Peaceful Valley Farm and Garden Supply
- Territorial Seed Company
- True Leaf Market (also has an excellent free guide for cover crops that you can download)
Help Desk of University of California Master Gardener Program of Contra Costa County (BHD)
- Author: Help Desk Team
Even though you may still be harvesting loads of vine-ripened tomatoes, peppers and other summer grown vegetables, in September it's time to make room for winter garden vegetables. If you delay, you may miss the chance to harvest full-sized heads of broccoli, cauliflower, and Romanesco.
Gardeners who make the mistake of waiting until the tomato plants have stopped producing ripe fruits before planting broccoli, cauliflower, or Romanesco seedlings are often disappointed by the results. When planted too late, these winter vegetables crops may produce only small “button-sized” heads, a phenomenon known as “buttoning." To produce full-sized heads, the plants need to grow plenty of large leaves while day-time temperatures still are well above 70 degrees and daylight hours have not diminished. The robust leaves are necessary to supply sufficient photosynthesis to energize the plants to produce full-sized heads.
When crops are planted too late, the plant leaves are still too small to create sufficient energy when the plant begins to produce the immature flower stalks that will eventually be harvested as a head of broccoli, cauliflower, or Romanesco. Consequently, the heads that are produced remain small.
So don't delay. It may be time to remove the squash or bean plants and substitute one or more of these brassica plants. In Contra Costa County, broccoli, cauliflower, and Romanesco can be planted as early as August and as late as mid to late September. The crops should be placed in the garden as sturdy seedlings. If you want to start your own seedlings from seeds instead of buying seedlings from a nursery, plan to start even earlier. You will need about six weeks to grow the seeds and harden up the plants to be ready to go into the garden. Be sure to provide good cultural care for the seedlings since any type of stress can also cause the plants to button.
When you put the seedlings into the garden, it would be a good idea to cover the plants with shade cloth or light-weight row covers. An internet search for “garden row covers” or “garden shade cloth” will help you find places to buy the covers. And a second search for “how to make hoops for row covers” will lead to videos and articles that show you simple ways to support the covers. Choose a row cover that will allow at least 70% of the sunlight to pass through so that the seedlings will receive sufficient sunlight to grow robustly.
The row covers will help protect the seedlings from the high daytime temperatures that many areas of the County receive in September. An added bonus is that the row covers keep the cabbageworm butterflies away from the seedlings so that they cannot lay eggs on the leaves that will quickly hatch into caterpillars with voracious appetites for the plant leaves.
If you miss the August–September window for planting, don't give up on growing brassica vegetables this year. Kohlrabi, cabbage, and kale are more forgiving and can be grown successfully if seedlings are placed in the garden in October.
Incidentally, September is also the time to plant seeds to grow carrots, beets, parsnips, and other root crops. No room in the garden? Containers work well for all the root crops.
Worried about using water for a winter garden during a drought? Keep in mind that you should always have plants growing in your garden beds to maintain healthy soils. After summer crops are removed, you can grow cool season vegetables or plant cover crops. Cool season crops use much less water than summer crops. A vegetable plant that is 2 feet wide growing in Pleasant Hill needs 2 gallons per week in July, but a vegetable plant of equal size needs less than half a gallon per week in November and even less in December and January. With cooler fall and winter temperatures and a good layer of mulch below your winter crops, even occasional rain can keep the soil moist and provide the needed water.
For guidance on growing cool season crops, use this website and click on the crop you want to plant: https://cagardenweb.ucanr.edu/Vegetables/
For advice on managing pests and diseases affecting your crops, use this website and click on the vegetable name: http://ipm.ucanr.edu/PMG/GARDEN/veggies.html
Help Desk of the UC Master Gardener Program of Contra Costa County (TKL)