September 04, 2015
The tomatoes are nearly spent, the zucchinis have been handed around to all the neighbors and the green bean stalks are looking tired. Most of us are about done with our vegetable gardens come September. But this is no time to rest. A little care now will yield wonderful edibles throughout the winter and improve the soil for the beds you plant come spring.
?The first step to a healthy winter garden is soil preparation. September is an ideal time to dig in 2 to 3 inches of compost. If you have heavy clay soil — and most of us start with that in Marin — add some fir bark or rice hulls to increase air penetration.
?Another winter trick for improving soil is to plant a cover crop, also known as “green manure.” Cover crops are generally legumes planted from seed in the fall that release nitrogen from their roots into the soil. Nitrogen promotes strong leaf growth and plant development. Examples of good cover crops in Marin include fava beans, alfalfa, winter wheat, rye, crimson clover and vetch. These crops add color to an otherwise-fallow winter vegetable bed while working hard to improve your soil. When it comes time to start your spring garden next February, simply till the cover crop into the soil or else clip the plants and add them to your compost bin.
?This may sound like a lot of work, but the pay off is fantastic soil. You won’t have scraggly roots and starving plants and, as the years go by, your soil will just get richer and easier to handle. I get enormous pleasure from digging in my lovely soil that started out 20 years ago rock-hard and nutrient-free. My plants would die and, when I removed them, the roots would still be in the hard, container-shaped ball I planted. I am delighted to report that improved soil will lead to much happier plants.
?So let’s say you want a real winter edibles garden, what do you plant in September? Plants that would bolt too fast in hot weather but enjoy cooler fall and winter days are the key. You can start fava beans, which also work as a cover crop as mentioned above, leeks and peas. Peas will even tolerate mild frosts. Leafy greens such as spinach do best planted from seed in fall gardens, as summers are too hot for them.
?Root vegetables like radishes, turnips, carrots and beets can be successfully grown, also best from seed, at this time of year. Most prefer daytime temperatures between 60 and 65 degrees, and don’t do well when it is above 75. Fall is the time to transplant starts of cabbage and cauliflower. It is also time to put in artichoke rootstock.
?For berry lovers, fall is a good time to plant blueberries in varieties such a ‘Bountiful Blue,’ ‘South Moon,’ ‘Sunshine Blue,’ ‘Chandler,’ ‘Misty,’ ‘Jubilee,’ ‘O’Neal’ and ‘Sharp Blue.’ These new varieties fare better in Marin than the older ones like ‘Early Blue,’ ‘Blue Ray’ or ‘Berkeley’ because they do not require as many hours of cold weather (called “chilling hours”) over the winter in order to bear fruit.
?Once you have planted your winter garden, top the soil with 2 to 3 inches of mulch to keep down weeds and increase water retention for better root growth. Additionally, mulch provides a perfect environment for development of the worms and micronutrients, another simple gardening technique that will enrich your soil. Mulching can be done with many materials, including compost, bark chips, rice hulls or alfalfa hay. Just be sure to keep the mulch 4 to 6 inches from the trunks of the plants to avoid crown rot.