How to help your garden through fall

Question: It’s October and I’m still harvesting my summer vegetables, yet it’s obvious that garden plants are losing vigor. The days are noticeably shorter. What are the garden tasks I need to consider now?

Answer: Soon you’ll need to harvest the last of the summer vegetables and tender herbs, before the first frost. If you want to extend the season for warm-weather crops such as tomatoes, peppers and eggplants by a week or so, you could install row covers and cold frames for frost protection.

As veggies fade, cut plants off just below soil level to preserve the soil microbiology on the roots. If you’re immediately replanting the bed and encounter the existing subsurface root, leave it in place and position each new plant start to the side, then add a 2-inch layer of compost around the new plant. Toss any plants showing signs of pests or disease in the trash. The rest can go in the compost.

It’s also time to move tender houseplants inside.

Q: Your recommendations about plant removal are new to me. What is the reason for not just yanking the whole plant, root and all, from the garden?

A: Garden advice has been updated recently. Scientists have become increasingly aware that soil health is fundamental to successful gardening. These days we advise minimal digging into the soil when caring for established garden beds. No-till methods, such as letting plant roots remain in the soil, preserve the natural web of soil life that includes earthworms, fungi, bacteria and other macro- and microorganisms. When soil structure is undisturbed, it builds up a system of pores that moves water up, down and sideways, resulting in more efficient use of water.

Q: I’m still debating whether to put my garden to bed for the winter or to try growing a few cool-weather vegetables. What tasks need to be done now, no matter what I decide?

A: No matter what you decide about a winter garden, fall cleanup time is here. Begin by raking leaves and picking up fallen fruit. As you clean up the vegetation from your summer garden, it’s important to cover any bare soil. Plan on laying down a layer of mulch or compost or plant a cover crop (more on that below). As mulch decomposes, it provides nutrient-rich food for soil microbes and plant roots. This organic matter improves soil health, creates and maintains good soil structure, retains water and sequesters carbon.

Q: I have trees on my property. Can I use the fallen leaves as mulch?

A: Yes, leaves make good mulch. Rake leaves into a pile, shred or run the mower over them and apply 3 to 4 inches of leaf mulch on top of the soil. Keep in mind that we are in wildfire season. Follow Cal Fire guidelines regarding defensible space, and keep all combustibles, including mulch, 5 feet away from structures.

Q: What about planting a cover crop in some areas of my garden?

A: That’s a great idea. Cover crops add nitrogen and organic matter, improve the soil tilth and water penetration and help mitigate diseases related to crop rotation. Some options for cover crops include fava beans, red clover and field peas. Garden stores and catalogs usually have a supply of cover-crop seeds. Plant soon so the seeds have a chance to sprout while there’s still sufficient daylight. Allow the cover crops to grow until late winter or early spring next year, then cut down the crop just as flower buds begin to form, leaving the roots in the soil. You can simply “chop and drop” the tops or put them in your compost pile. Then lay 2 or 3 inches of compost over the top of the garden and allow to fallow until you are ready to plant your spring or summer garden.

Q: What if I use part of my garden to grow some winter vegetables? What plants would do well in the cold?

A: We Master Gardeners have a slogan: “right crop, right place, right time.” Choose cool-season vegetables you enjoy eating, which means ones that do well in temperatures under 70 degrees and are typically planted in early spring or late summer into early fall.

Then carefully consider timing, which is critical when planning a winter garden. You need to get the seeds or starts in the ground before “Persephone days” set in. These days begin when daylight falls to fewer than 10 hours and continues to decrease. In Sonoma County, this date is Nov. 18. After Nov. 18, there are fewer than 10 hours of sunlight from dawn to dusk.

Why does this matter? When daylight diminishes to fewer than 10 hours, a seed or young plant doesn’t receive enough sunlight to sprout or photosynthesize sufficiently to produce vibrant growth. For timing your winter garden, that means your winter garden plants need to be about 50-75% mature by Nov. 18. If a plant is already established or well on its way to maturity, it will continue growing and you’ll be able to harvest over the coming months. With careful timing and plant selection, your harvest will likely continue into early spring.

If you get your plants in too late for a winter harvest, you’ll still be able to enjoy an early spring harvest. Keep in mind that many greens, roots and herbs are delicious when harvested young and tender. Also, many cool-weather crops sweeten and deepen in flavor with colder weather.

Q: What plants do you suggest planting for a cool-season garden?

A: Because we’re already in October, you’ll need to plant vegetable starts. It’s too late to plant seeds, which should’ve been planted in late July, August or September.

  • You can plant garlic, onions and shallots. Sets are often available at nurseries or you can buy them by mail-order in early fall.
  • Vegetables you can grow right now include cabbage, cauliflower, fennel bulb, kale, broccoli, spinach, chard, chives, cilantro, collards, dill, lettuce, parsley, peas, radishes, carrots, parsnips, turnips and beets.
  • You also can sow flower seeds now, such as winter and spring bulbs, spring wildflowers, bee balm, calendula, candytuft, clarkia, cornflower, columbine, coreopsis, dianthus, foxglove, larkspur, nigella, pansy, poppy, snapdragon and sweet pea. It’s also a good time to plant artichokes.

For more information about winter gardening, visit our Sonoma County Master Gardener website:

Contributors to this week’s column were Sally Singingtree, Diane Judd and Joy Lanzendorfer. The UC Master Gardener Program of Sonoma County,, provides environmentally sustainable, science-based horticultural information to Sonoma County home gardeners. Send your gardening questions to [email protected]. You will receive answers to your questions either in this newspaper or from our Information Desk. You can contact the Information Desk directly at 707-565-2608 or [email protected].

Related Posts