Vegetables All Year
Some of the big pleasures of summer for many folks in Napa Valley are juicy fresh tomatoes, flavorful basil and other gifts of the summer garden. Before I became a Master Gardener, I started to mourn when fall arrived, because it seemed like the best gardening time of year was over.
Happily, that’s not the case anymore. We’re blessed with a Mediterranean climate, and that means we can literally grow vegetables all year long. In fact, in our climate, the natural growing season is fall through spring - our rainy season. Summer may bring those amazing tomatoes, but fall brings sweet, fresh broccoli and kale, peas, and tasty
lettuces and Asian greens - all those vegetables that struggle during our summers. Autumn gardening also means less watering (if we get normal rainfall, for which I’m keeping my fingers crossed).
If you’ve never had a fall and winter garden before, there are a few things to consider: what to grow, when to plant and harvest, and how to nourish your soil. Vegetables are divided into cool-season and warm-season crops. Cool-season crops prefer temperatures below 75°F, and their seeds will sprout in cooler soils than seeds for warm-season crops. Warm-season crops (think tomatoes, peppers, melons and squash) need warm soil and lots of heat. Cool-season vegetables tend to be plants that we grow for their leaves (lettuce, arugula, and spinach); roots (beets, carrots and radishes anyone?); or flowers (such as cauliflower and broccoli).
While it is often still quite warm in the fall, the amount of sunlight we get each day is decreasing rapidly, and that has a big effect on your garden. In the summer, if you delay planting by a week or two, it often makes almost no difference in when you first harvest ripe vegetables. In the fall, losing a week or two can mean a delay of twice that long in your harvest.
Napa County Master Gardeners recommend planting broccoli seedlings in mid-September for harvest around Thanksgiving. If you plant them earlier, you will be able to harvest that much earlier. Next year, consider planting broccoli seedlings in mid-August for a harvest by Halloween. Between mid-November and mid-January we get relatively little sunlight and, of course, it’s quite cool. Most vegetable plants grow little during this time. You can use that to your advantage by planting some extra plants to have a harvest from fall through winter.
Most cool-season vegetables can tolerate some frost. Kale and kohlrabi even taste better after night frost. Don’t be dismayed if, after a frost, your lettuces and broccoli look like they are done for. Most likely they will recover completely by mid-morning. You may have to witness this phenomenon a few times before you really believe that something can look nearly dead and yet perk back up completely.
You can also get a head start on your spring garden. If you plant cool-season vegetable seedlings in mid-October, they will grow a little, but they won’t mature. Once we get longer days and slightly warmer temperatures, they will take off, and you will have fresh spring vegetables weeks earlier than if you started planting in the spring.
When you garden year-round, you need to pay more attention to your soil because it’s working harder. Make sure that you fertilize and add organic matter, such as compost. Organic fertilizers are better for your soil than synthetic fertilizers, and
they don’t break down as quickly, releasing nutrients slowly.
The easiest way to add organic matter is to mulch around your plants. The friendly worms living in the soil will do all the work of mixing the compost or other organic matter into your soil. Earthworms have been shown to move organic matter 12 inches down into the soil in a year.
Mulching around your plants has many other benefits. It inhibits weeds, keeps your soil temperature more consistent (warmer in the winter, cooler in the summer), retains moisture, and protects the structure of your soil. I prefer to mulch after we have had several good rains so that the soil is moist.
Early September is not too late to start some plants from seed. Leafy greens, in particular, tend to mature quickly; if you start some lettuces now, you will mostly likely be able to start harvesting by mid-October. Tat soi and many other Asian greens also grow quickly. Seed packets (if you’re planting from seed) and seed labels (if you’re planting seedlings) will tell you the days to maturity for the vegetable you’re considering.
In the fall, choose varieties that mature quickly. Broccoli seedlings take 60 to 90 days to mature, and leaf lettuces mature in 45 to 75 days when planted from seed. Take the stated days to maturity with a grain of salt. Because we have less light, everything will take longer than the label or package says. One final way to get fresh vegetables quickly is to grow mesclun. Seed catalogs offer a large variety of these lettuce mixes, and your first crop can be ready in 5 to 6 weeks.
The Master Gardeners of Napa County are available to provide free advice. Visit the Master Gardener website for a vegetable planting chart (napamg.ucanr.edu) or call 253-4221 between 9 am and noon on Mondays, Wednesdays or Fridays.