With summer vegetables hitting their stride, it's time to start thinking about extending your garden bounty into fall. For most areas in Salt Lake, Davis, and Utah counties, according to Utah climate data, average first frost hits around mid-October, leaving about seven weeks of frost-free weather. After frost, all tender vegetables quit producing, unless they're protected. But you can increase your garden's productivity by planting cold-hardy vegetable varieties now.
Here are some tips for success at fall gardening:
Know what's hardy » Hardy vegetables can survive and produce crops even after exposure to temperatures as low as 21 degrees. Hardy vegetables include turnips, cabbage, kale, mustard greens, broccoli, kohlrabi, green onions and radishes.
Vegetables are called semi-hardy if they can survive and still produce a crop after frost, when night temperatures reach 32 degrees F. Typical semi-hardy vegetables include beets, cauliflower, spinach and Chinese cabbage.
Find a source of transplants » Transplanting fall crops is the quickest, easiest method to start a fall garden. However, finding vegetable bedding plants to buy in late summer can be challenging. Most garden centers traditionally haven't offered new plants at the end of the season, although that may change due to recent increased interest in home gardening. Places that are more likely bets to find these starts include independent garden centers and nurseries. Farmers' markets may offer hardy transplants, too.
Select early varieties » Vegetable varieties that are described as "early" will reach harvest maturity more quickly, which makes them preferred for planting now. Early autumn's cooler temperatures and shorter days will slow plant growth, so choosing vegetables that mature quickly is a good fall gardening strategy. Unless you intend to protect semi-hardy plants with season-extending devices, choose semi-hardy varieties that claim 50 days or less until harvest. Hardy vegetables planted in mid August can produce crops into mid November, depending on the weather.
Plant within the existing garden » Planting within the existing vegetable garden means you won't need to spend a lot of time and energy preparing the soil or setting up irrigation, assuming you've maintained the vegetable garden throughout summer. In empty spaces where summer vegetables have failed, fill in with cold hardy vegetables. Most cold hardy vegetables aren't susceptible to the same diseases and pests that might have killed your tomatoes, so don't worry about planting in their places. Consider that many fall crops can double as ornamentals in flower beds and pots, especially leafy vegetables like kale, Swiss chard and lettuce. This year instead of planting all pansies, try enhancing annual flower beds with edible crops.
Protect seeded crops from summer sun and heat » Growing fall vegetables from seed can be tricky; seed beds dry quickly thanks to late summer's hot temperatures. To protect direct sown seedlings from the hot summer sun, build a temporary shade cover over seed beds. Once seedlings emerge, apply a layer of fine mulch to help keep the soil moist and cool.
Maggie Wolf , a certified professional horticulturist, gardens and consults in Salt Lake City.