Late Summer Vegetable Garden

Zucchini on vine1

Zucchini on vineBegin to think about harvest in mid to late summer. Warm-weather crops will be ready then. Keeping the soil evenly moist as crops finish maturing is important; you will stop watering many crops just a week or two before picking to concentrate flavor.

Succession planting of summer crops where there is enough season left before the first frost can begin now. Planting cool-weather crops for harvest in autumn or early winter can begin in mid summer.

Harvest. The late summer garden harvest includes: onions, potatoes, garlic, shallots, leeks, cabbages, celery, eggplant, and pepper.

Harvest each crop as soon as it starts to bear edible-sized vegetables. Don’t wait for crops to become oversized; you will sacrifice flavor. Keep picking so the plant will keep producing. Record your harvest dates for each crop to use in planning coming seasons.

Tomatoes, melons, winter squashes and pumpkins will come to harvest in late summer. About six weeks before harvest, remove the growing tips of tomato plants, melons, winter squashes, and pumpkins. Pinch out the tip of tomato vines about two leaves above the top truss of tomato flowers. This will channel the plants’ energies into fruit development and away from leaf growth.

Excessive heat and over-watering can reduce the sweetness of tomatoes, cantaloupes, and melons. Shade plants from too hot weather and reduce water in the last week or two before harvest. Cool or cloudy weather can also result in less sweet fruit.

Late summer planting. If you do not expect your first frost until mid autumn, there is time to plant second and third crops. Check the days to maturity for each crop you want to grow; add a week or two to the days to harvest to factor in the shortening of days as autumn approaches. Choose crops that can come to harvest before frost or crops that do not mind being touched by frost or cool weather. Choose quick-maturing crops.

Spinach, lettuce and greens, beets, carrots, peas, and beans can be sown now. Most seeds will readily germinate in the garden now because the soil holds heat well into autumn; warm soil (in the 70°s) is ideal for seed starting, as long as the weather is not too hot. Put out transplants if there is not enough season left to grow from seed. In long-summer and warm-autumn regions protect transplants from lingering heat; use shade and water to keep developing crops cool.

In regions where frost will not come until late autumn, start celery, broccoli, cauliflower, cabbage, and Brussels sprouts for setting out in the garden in late September and early October. In cooler regions, these crops may need frost blanket protection before harvest.

Fall crops. Fall crops that can tolerate cool temperatures and mature quickly include: small, round beets, short carrots, radishes, winter radishes, bunching onions, mustard greens, leaf beets, Swiss chard, kale, and spinach.

Brussels sprouts. Start Brussels sprouts for harvest early next year; sow seeds ½ inch deep in drills 6 inches apart. Started indoors these can be set out in six weeks.

Brussels sprouts in the garden now can be left in place until after cool weather arrives; remove the tip of the plant when lower sprouts are ¾ inch in diameter about four to eight weeks before the desired harvest; this will trigger the development of sprouts higher up.

Cabbage. Start cabbage indoors now; sow seeds of spring cabbage ½ inch deep in drills 6 inches apart. A spring and fall crop in northern regions is a winter crop in the South. (Early or spring cabbages mature in 50 to 60 days from transplanting; mid-season cabbages mature in 70 to 85 days from transplanting; late-season–called storage cabbages–require 85 days or more after transplanting.) Early-maturing cabbages are milder flavored.

Celery. Celery prefers daytime temperatures between 65°F and 75°F. It requires 80 to 130 days to harvest depending upon the cultivar. Begin to harvest self-blanching celery as soon as stalks are large enough to eat. Celery should come out of the garden before the first frost.

Corn. Corn pollination can be hampered by hot and dry or wet and rainy weather. Pollination affects how well the ears fill out; if pollination is incomplete, kernels and ears will be underdeveloped. Watering is critical during ear development. Most cultivars are ready for harvest about 20 days after the silks (also called “tassels”) appear.

Pick sweet corn when the tassels on the end have withered and the seeds are firm and exude a milky substance when pressed with your thumb nail. Gather the ears by breaking them off the stems.

Corn earworm can be a problem; they commonly feed on the top kernels in an ear. Prevent earworm damage by placing a drop or two of mineral oil into each ear when silks first emerge.

Cucumber. Pick slicing cucumbers when 6 to 8 inches long; harvest picklers when 3 to 4 inches long. Cucumbers left on the vine too long will become bitter and seedy. Harvest cucumbers regularly to keep the plant producing new fruit. Pinch off blossoms a month before the first expected frost to channel energy into existing fruit.

Eggplant. Pick eggplants while they are still shiny. Bigger eggplants are not better-tasting eggplants. Pinch back new blossoms three weeks before the first frost so that the plant’s energy is channeled into existing fruit.

Garlic. Lift garlic when three-quarters of the tops have yellowed. Dig one or two plants first and check to make sure cloves are well segmented and easy to separate; if not, they need more time. Garlic harvested with green tops will not store well. Cure bulbs before storing by spreading bulbs in a single layer on a screen in a warm, dry, airy place out of the sun. Bulbs will cure or dry in two to three weeks.

Lettuce. Sow lettuces for cutting in autumn and early winter. Sow the seed ¼ inch deep in drills 6 inches apart; thin seedlings from 8 to 18 inches apart, depending upon the cultivar. For a spring lettuce crop to over-winter without protection plant to set out the cultivars ‘Winter Density’ or ‘Arctic King’ in early October.

Melons. Muskmelons and cantaloupes will develop small crack where the stem joins the fruit as ripening occurs. Near ripeness, the netting effect on the skin will become more pronounced and the netting lines will turn from green to tan as the fruit ripens. Pick the fuzzy ends off vines to concentrate growth and flavor. Press your thumb at the fruit-stem junction; the stem will separate from the fruit with a slight pull if the melon is ripe.

Onions and shallots. When the top stems of bulbing onions and shallots are three-quarters dry and falling over, bend the tops over further. Brush the soil away from the tops of the bulbs to allow them to fill out and dry in preparation for harvest. Bulbing is hastened not by the bending over of the stems but by long days.

Parsnip. Parsnip and salsify can come to harvest in slightly dry soil; water only if the soil is very dry. Dig parsnip and salsify as soon as they are large enough to use; waiting until after the first few frosts will concentrate flavor.

Pepper. For the best growth and ripening of peppers, remove the central, top pepper on each plant. This will increase your yield. Allow not peppers to ripen on the plant for maximum “hotness.” Sweet peppers can be picked “green”–meaning immature or after reaching full color.

Potato. Early potatoes baby potatoes can be harvested small, just seven to eight weeks after planting. Harvest main crop potatoes about two weeks after the tops have been yellowed and browned by the first frosts. Complete the potato harvest before the first hard frost.

Pumpkin and winter squash. Pumpkins and winter squash will need regular watering to come up to size before harvest. Turn each fruit just a little regularly to prevent a flat side at harvest. Remove the flowers on pumpkins and winter squashes plants about 8 inches back from the growing tips of vines; this will help increase the size of fruits.

Summer squash and zucchini. Summer squash and zucchini should be picked before the rind hardens.

Sweet potato. Sweet potatoes are drought tolerant but regular, even water leading up to harvest will produce the best sized roots. Sweet potatoes can be lifted as soon as they are large enough to use; for the best flavor, leave tubers in the ground until the tops are killed by a light frost or daytime temperatures drop into the 50sF.

Tomato. Tomatoes ripen from the bottom; a tomato can be fully ripe before it becomes fully colored. When the skin begins to loose its waxy smoothness, even if you don’t see color on the shoulders, the tomato is ripe. The texture of a ripe tomato will be just between firm and soft. Picked too early a tomato will be less sweet and less juicy; picked too late, the skin will be tough and the flavor flat. Tomatoes continue to ripen off the vine; to slow the ripening store the tomato in a cool location, 50° to 55°F.

Watermelon. Watermelon is ripe when thumped and you get a “thunk” sound. Stop watering watermelon when it starts to ripen to increase the sweetness. A ripe watermelon will be yellowish, not white, where it touches the ground; the tendrils on the stem near the fruit will be brown.

Herb cuttings. Take cuttings of bay, hyssop, lavender, mint, rosemary, rue, and sage, and insert in sandy soil in open ground or in a pot filled with sand. Keep cuttings out of direct sun and wind for the first two weeks. Water cuttings in the evenings until the roots have formed.

Seed drying. Seeds from chervil, dill, fennel, anise, and coriander can be harvested for drying in the next few weeks. Harvest seeds when they are dry but before they drop to the ground. Place a paper bag over the seed head and give a shake to allow the ripe seeds to loosen and drop into the bag; you can also tie the bag around the seed head and let the seeds drop as they will. Lay seeds out on a clean paper in warm, dry place to allow them to finish drying. Gather the dry seeds of chervil and re-sow at once in 1 inch deep seed drills.

Divide chives. Chives need dividing about every four years; lift the clumps and cut into segments with a sharp knife, taking care that each segment retains a number of roots. Re-plant out new clumps 12 inches apart.

Storing herbs. Store dried herbs before they have had time to re-absorb moisture from the air (dry by spreading leaves or seeds in a single layer in a dry location out of direct sunlight). Rub dried herbs between your hands to be rid of stems and other chaff and then store right away to prevent dust collecting. For short-term storage, seal herbs in a plastic bag and refrigerate; for long-term storage, seal herbs in a glass jar and store in a dark place.

Written by Stephen Albert

Stephen Albert is a horticulturist, master gardener, and certified nurseryman who has taught at the University of California for more than 25 years. He holds graduate degrees from the University of California and the University of Iowa. His books include Vegetable Garden Grower’s Guide, Vegetable Garden Almanac & Planner, Tomato Grower’s Answer Book, and Kitchen Garden Grower’s Guide. His Vegetable Garden Grower’s Masterclass is available online. has more than 10 million visitors each year.

How To Grow Tips

How To Grow Tomatoes

How To Grow Peppers

How To Grow Broccoli

How To Grow Carrots

How To Grow Beans

How To Grow Corn

How To Grow Peas

How To Grow Lettuce

How To Grow Cucumbers

How To Grow Zucchini and Summer Squash

How To Grow Onions

How To Grow Potatoes

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