Keeping up with sweet corn, green beans and tomatoes may leave little time to think ahead to a fall garden. But autumn offers ideal weather to grow cool-season crops. Devoting a few hours now may net the garden’s best produce.
Crops that sprout in warm soil can be planted now in the garden, if the soil is kept moist. Try beets, kale and radishes. Even a fall crop of dwarf, fast-growing peas is possible if planted now.
Crops that sprout in cool soil can be can be started indoors or in the shade and transplanted to sunny spots when the weather cools. This method can be used for crops such as lettuce, endive and spinach as well as bok choy and cabbage.
To seed a fall garden, count back from the average date of the first frost (usually around Oct. 3 for Boone County) to find the correct planting time. Then check seed packets for days to maturity.
Cabbage requires 70 days to maturity and grows best in temperatures in the 60s (Farenheit). Cabbage may germinate in soil as low as 40F or as high as 85F, but germinates best at 75F. Outer leaves tolerate frost, but tender leaves inside may be damaged by a heavy freeze, so be ready to cover plants when necessary.
Bok choy (Chinese cabbage) requires only 55 days to maturity and prefers temperatures similar to cabbage. Both crops need to be kept from heat stress. Keep garden soil moist and provide shade during hot summer sun. Because bok choy has shallow roots, it also can be grown in shallow containers.
Leaf lettuce takes from 45 to 60 days to maturity, depending on the cultivar. Planting in late August to early September should allow enough time to harvest a crop.
Spinach does best when temperatures stay below 80F and daylight shortens to less than 14 hours. It can be sown up to 5 weeks before the first frost date. Once established, spinach can survive temperatures that dip below freezing.
Some fall crops make attractive container plants. Try leaf lettuce, parsley and perhaps a pansy that has made it through the summer heat. Cut pansies back if they’re leggy and they’ll bloom again. Dwarf marigolds also combine well with curly endive or kale.
For answers to horticulture questions, contact the Iowa State University Extension hotline at (515) 294-3108 or email firstname.lastname@example.org.