Planting vegetables in midsummer for fall harvest
UNIVERSITY OF MINNESOTA EXTENSION - www.extension.umn.edu
- Know the average first frost date in your area will help you calculate when to plant these late vegetables.
- Some vegetables will tolerate some frost and keep growing even when temperatures are in the low forties. Others cannot tolerate frost and stop growing in cool weather.
- Cool-season vegetables including kale and others in the cabbage family may be the best choice for mid-summer sowing.
- Before sowing these second crops, turn over the soil and mix in some balanced fertilizer to replace what earlier plants have used up.
- If it is too late to plant a second crop of vegetables, you may want to plant "green manure."
After harvesting early-maturing vegetables such as salad greens, radishes, peas and spinach, gardeners can plant other crops in midsummer for fall harvest. You can successfully grow some root crops, greens and other vegetables from late June, July or August plantings.
Know the average first frost date in your area
It is important to know the average first frost date in your area. This will help you calculate when to plant these late vegetables so they will mature before cold weather damage. The Midwestern Regional Climate Center has produced an up-to-date interactive map of first fall and last spring freeze dates.
Some vegetables will tolerate some frost and keep growing even when temperatures are in the low forties. Others cannot tolerate frost and stop growing in cool weather. Bush snap beans mature in 45 to 65 days, but even a light frost (temperatures between 30° and 32°) will kill the plants. Kale takes just as long to mature, but the plants continue to grow when temperatures are cool, and can survive cold down to about 20°F.
Cool-season vegetables including kale and others in the cabbage family may be the best choice for mid-summer sowing. An earlier-than-expected frost will not kill them before they are ready to eat. Many of the cold-tolerant vegetables actually have better quality when grown in cool weather.
Vegetables for midsummer planting
|Crop||Days to maturity||Cold hardiness|
|Basil||30-60||Killed by frost|
|Beets||50-60||Survives high 20s|
|Bush Beans||45-65||Killed by frost|
|Broccoli||50-70||Survives light frost|
|Brussels sprouts||90-100||The hardiest - down to 20°|
|Cabbage||50-90||The hardiest - down to 20°|
|Cauliflower||60-80||Survives light frost|
|Cilantro||60-70||Survives light frost|
|Collard greens||40-65||The hardiest - down to 20°|
|Garlic||Harvest the following July||Winters over in ground|
|Green onion||60-70||Survives high 20s|
|Kale||40-65||The hardiest - down to 20°|
|Kohlrabi||50-60||Survives light frost|
|Leaf lettuce||40-60||Survives light frost|
|Mustard greens||30-40||Survives light frost|
|Peas||70-80 (longer than if planted in spring)||Survives high 20s|
|Radishes||30-60||Dig until soil freezes|
|Spinach||35-45||Survives light frost; may overwinter|
|Swiss chard||40-60||Survives light frost|
|Turnips||50-60||Survives light frost|
You can harvest leafy vegetables, such as Swiss chard, kale and mustard greens before the leaves reach full size. These small leaves are tenderer and tastier than mature ones. Plant these crops in succession every few weeks over the course of the spring and summer to provide a steady supply of young leaves.
Lettuce may bolt and taste bitter when grown in the heat of summer. Enjoy it in spring or wait until temperatures cool to plant a late crop. Shade from taller plants may help improve the quality of summer-grown lettuce, as will selecting varieties suited for warm weather.
Basil and cilantro are fast-growing herbs that are ready for harvest about a month after sowing the seed. Garlic planted in September produces the biggest bulbs the following July. After harvesting a late-maturing crop, you can plant garlic in that space.
Before sowing these second crops, turn over the soil and mix in some balanced fertilizer to replace what earlier plants have used up. Leftover debris like stems or roots from the first planting can cause problems in seed germination if you do not remove them or allow them to break down. Wait one to two weeks before seeding the second crop, or be sure to remove this material as completely as possible.
If it is too late to plant a second crop of vegetables, you may want to plant "green manure" to keep the area weed-free, prevent soil erosion and add organic matter to the soil.