- 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)
- 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)
