This article was written by Mary Roduner, former SDSU Extension Consumer Horticulture Field Specialist.
It’s that time of year; the days are shorter and getting cooler, your tomato plants look pretty bad after that light frost the other night when you couldn’t cover them up and you are asking what the next step is for your garden.
Fall cleanup can help with the success of your garden next year. Diseased plants left over the winter will provide fungal spores or virus particles ready and willing to infect your new plants. It is also a good idea to get as much done in the fall as possible because spring could be late, cool or wet again like it was the last two years. If you have to do cleanup next spring, and wait for the weather to cooperate so you can work the soil, it may be too late for cool season crops. When cleaning out your vegetable garden follow these steps.
First go through the garden to look for and pick anything that was missed earlier. Sometimes a pepper or tomato will be hiding under plant material and survive a light freeze. If you don’t plan on overwintering your beets or carrots in the garden pull them and store in a refrigerator long term. Kale and spinach can be left in the garden. If temperatures don’t get too low, both will overwinter and give you a treat next spring.
If there were any disease problems during the summer, pull these plants, roots and all; bag them and put in the trash. Spores and virus particles will overwinter causing new plants to be infected much earlier than if the diseases have to move in with the weather or insect infestations. All tomatoes, peppers and eggplant that show any signs at all of virus problems must be removed. Powdery mildew spores will overwinter on soil protected by the leaves that fall and remain in place for the winter. Squash plants are very prone to powdery mildew and need to be removed and put in the trash.
It is important too, to make note of where tomatoes or peppers infected with the soil-borne fungi, fusarium or verticillium, were planted, and avoid planting anything in the nightshade family in this location for the next 6-10 years.
Plants That Are Not Diseased
These plants are valuable organic matter for next year. You can pull the plants and run a lawn mower over them so they are chopped into smaller pieces and spread over the ground on the garden. They will decompose over the winter, returning nutrients to the soil. These plants can also be composted and the finished compost used next season.
Adding Soil Amendments
Fall is the best time to add amendments like well-rotted manure, leaves, compost, and disease free garden waste. All manure needs to be at least a year old to prevent root burning next spring. The type of manure is not as important as the age. Chicken manure is known for being “hot”, or very strong, so use caution with the amount applied. In an average garden with good soil, about 1” per year of cow or horse manure or ½” of chicken manure is all that is needed. Too much manure over several years will cause salts to build up in the soil and plants will not survive.
Leaves are good organic matter. Thicker leaves take longer to break down and help loosen heavy soil. Whole leaves can be layered on the soil and pulled back next spring to let the soil warm and dry. These half decomposed leaves can then be used as mulch when the garden is replanted. Leaves can also be chopped with the mower and spread out. Chopped leaves will decompose faster and may not need to be raked off in the spring.
Compost purchased at local landfills can be applied at this time too. Several inches can be spread on the soil and allowed to continue decomposing over the winter. Since decomposition uses nitrogen, don’t forget to supplement with extra nitrogen when planting next spring.
Tilling in the fall is a personal decision. If you have heavy clay soil that needs amending to loosen it, tilling during fall cleanup will mix the mulch, compost or manure into the soil, speeding improvement. If your soil has been improved over several years and has good tilth, is loose and feels soft to the touch you don’t need to till in the fall. Amendments can be spread on the soil or worked in with either a hoe or fork.
Over tilling will break soil particles into very small pieces that remove air spaces and cause compacting. By following good soil amendment and care practices, some gardeners have given up tilling and are very pleased with the results. No-till or layered gardening methods like lasagna gardening will improve soil and eliminate the need for tilling. This link will give you basic instructions for starting a layered or lasagna garden.