What to Plant in Summer for a Late Harvest This Year

The rule for summer planting is simple: add the days-to-maturity on the seed packet to today's date, then add a two-week buffer for shortening autumn days. If the total lands before your first expected frost, the crop fits. Fast crops like radishes, arugula and baby kale need only 25 to 40 days, which makes them safe to sow well into late summer in most climates. Anything that needs more than 90 days is usually a gamble by midsummer.

Beets, carrots, turnips, rutabagas and parsnips sown in midsummer mature in cool weather, when they convert starch to sugar, which is why fall roots taste noticeably sweeter than spring ones. Keep the seedbed consistently moist, because summer heat and dry soil cause woody, bitter roots and poor germination. A thin layer of compost or straw over the row holds moisture and keeps the soil temperature down.

Broccoli, cabbage, cauliflower, kale and Brussels sprouts grow better as autumn crops than as spring ones in most regions, because they mature in cool weather instead of bolting in the heat. Start them in trays in a shaded spot and transplant four to six weeks later, when they have four or five true leaves. Keep them well watered and watch for cabbage worms, which are far more active in warm weather and can strip a seedling overnight.

If you still want summer vegetables, bush beans, cucumbers and zucchini sown in early summer will produce before the season ends. Bush beans take about 50 to 60 days, so a July sowing usually delivers a September pick. Choose the fastest-maturing varieties you can find, and water them deeply rather than often, since midsummer soil dries out fast and shallow watering only encourages weak roots.

Summer seedbeds need help, because germination stalls when the surface soil dries within hours. Water newly sown rows lightly twice a day until they emerge, and rig shade cloth or a floating row cover to cut the midday sun by 30 to 50 percent. Sowing in the late afternoon also gives seeds a full night of moisture before the sun returns. Once seedlings are up, thin them promptly so they are not competing for every drop.

Mulching is the other half of the answer. A 5 cm layer of straw, grass clippings or compost over a summer seedbed stops the surface drying out between waterings, holds the soil temperature down and shades out weed seedlings at the same time. Pull it back a little from the stems of young plants so the bases stay dry and air can move around them.

Late summer is the moment to plan the gap. As beans, cucumbers and early brassicas finish, sow something quick in the space rather than leaving it bare — a fast salad mix, rocket or spinach will crop before the weather turns, and a green manure sown in early autumn covers the ground over winter and can be dug in next spring.

Keep a note of what came out and what went in, because summer plantings are the ones most easily forgotten by the following spring. If a bed has carried a heavy crop, spread a couple of centimetres of compost over it before the next sowing. Summer watering leaches nutrients quickly, and replanting into tired soil is why second crops so often disappoint.