August garden tasks US — fall planting + harvest

August garden tasks US — fall planting + harvest

August is the pivot month in the US garden. The summer harvest still demands daily attention while the fall planting window opens and closes inside 30 days for most of the country. Miss the window and you have bare beds through October; hit it and you double your yearly yield. This guide is the practical US August calendar, split by USDA zone, with the cooperative extension-aligned timing experienced gardeners use to turn the second half of the season into a real production window. It continues the series from the July garden tasks and hands off to the September garden tasks; localise every date with the frost date calculator, and see every month in the garden calendar hub.

Don't miss the fall window: Add your ZIP to Growli and the app counts back from your average first fall frost — so the kale, spinach, broccoli and carrot reminders fire on the exact day your zone needs them, not on a generic chart date.

August climate snapshot by USDA zone

August feels like July but the days are getting noticeably shorter and night temperatures soften, especially in cold and mid zones. That swing flips the fall sowing window open.

The binding constraint in cold zones flips from heat to short-season risk. Brassicas, fall carrots and roots planted in August must mature before the November freeze. In warm zones the constraint stays heat — late-August sowings face one more hot fortnight before September relief.

Sow + plant this month by zone

Cold zones 3-5 — the final fall window

The northern tier has roughly 30 days of usable fall planting. Miss the first week of August and most fall vegetables run out of growing degree-days before frost.

• Direct-sow early August (first 10 days): lettuce, spinach, arugula, mustard, mizuna, fall radishes, daikon, salad turnips, kohlrabi, fall carrots (60-day varieties only — Nelson, Mokum).
• Direct-sow mid-August: spinach, arugula, mache, claytonia, winter greens. Cover with row cover in late August to extend the season into November.
• Plant out from July indoor sowings: broccoli, cauliflower, cabbage, Brussels sprouts, kale, kohlrabi, Swiss chard. Set transplants the first two weeks of August.
• Plant strawberry runners for next year's June crop.
• Order garlic for October planting if you have not already.

Mid zones 6-7 — second main planting

The mid zones get the fullest fall window of any band — 6-8 weeks of usable sowing time.

• Direct-sow now: lettuce, spinach, arugula, mustard, mizuna, kale, collards, fall radishes, daikon, salad turnips, kohlrabi, fall carrots, beets, Swiss chard, peas (sugar snap and snow types for October pick).
• Plant out from July indoor sowings: broccoli, cauliflower, cabbage, Brussels sprouts, kohlrabi.
• Last bean sowing (bush varieties only, 50-day) for late September picking.
• Aerate cool-season lawns (Kentucky bluegrass, tall fescue, ryegrass) and overseed in the last week of August through mid-September.
• Plant strawberry runners for next year's crop.

Warm zones 8-10 — fall garden begins

The South and Southwest fall-garden window opens in August once the worst heat starts to break.

• Direct-sow mid- to late August: beans, cucumbers (heat-tolerant), summer squash for fall crop, southern peas (final sowing).
• Direct-sow late August: fall lettuce (bolt-resistant Jericho, Muir), arugula, mustard, collards, kale, mizuna, fall radishes.
• Plant out fall transplants: tomatoes (heat-set varieties), peppers, eggplant, tomatillos for October-November harvest. Set transplants in shade for 3-4 days before exposing to sun.
• Hold off on broccoli, cabbage, cauliflower until late August (zone 8) or September (zones 9-10). Heat blocks brassica heading.

Maintain — watering, pruning, lawn

• Water deeply through late-summer dry spells — established beds need 1-2 in of water per week. Newly set fall transplants need daily watering for 7-10 days, then taper.
• Mulch any thin or exposed beds before the September sun-and-wind dry-out window.
• Pinch suckers on indeterminate tomatoes through mid-August, then stop and let the plant ripen what is on the vine.
• Top runner beans, pole beans and climbing cucumbers to redirect energy into pod fill.
• Deadhead annuals and roses weekly to extend bloom into September.
• Cut back early-summer perennials (catmint, salvia, daylilies, geraniums) by half for a fresh September flush.
• Take softwood and semi-ripe cuttings of fuchsia, lavender, rosemary, sage, salvia, pelargoniums, hydrangeas and many shrubs. Root in a 50/50 mix of perlite and peat or coir under a humidity dome.
• Cool-season lawns (zones 5-7): aerate, dethatch and overseed from mid-August through mid-September — the single highest-leverage lawn job of the year. Warm-season lawns (Bermuda, zoysia, St. Augustine) — last fertilization for the season.
• Stop fertilizing trees and shrubs — new growth pushed in August will not harden off before frost in cold and mid zones.

Pest and disease watch — US August

The August pest list is the year's last big wave:

• Late blight on tomatoes and potatoes — humid August weather in the East and Pacific Northwest is peak risk. Outbreaks tracked at USABlight.org. Remove and bag affected plants in trash, not compost. Save seed only from unaffected plants.
• Stink bugs — pierce tomato and pepper fruit causing corky yellow spots. Hand-pick or vacuum at dawn. Brown marmorated stink bug (the invasive Asian species) is established across the Mid-Atlantic and spreading.
• Squash bugs — gray, flat adults and clusters of bronze eggs on undersides of squash leaves. Crush eggs weekly; trap adults at night under boards laid in the bed.
• Tomato hornworms — continue daily inspection through late August.
• Cabbage white butterflies and cabbage loopers — peak egg-laying on newly set fall brassicas. Cover with insect mesh from transplant day.
• Aphids — second wave on roses, fall brassicas, peppers, lettuce.
• Powdery mildew — peaks late August on cucurbits, peonies, bee balm, phlox, lilacs. Cultural fix: water at soil level, prune for airflow, choose resistant varieties next year. See powdery mildew.
• Spider mites — peak in dry weather on tomatoes, eggplant, beans, melons. See spider mites.
• Yellowjackets — peak nest size in August; their food shift from protein to sugar makes them aggressive around fallen fruit. Avoid sweet drinks outdoors.

Harvest now

August is the production-peak month for most of the lower 48:

• Tomatoes — peak picking nationwide. Pick fruit at first blush of color and ripen indoors during heat waves to prevent splitting.
• Peppers — bell, jalapeno, banana, poblano, habanero all in full production zones 6-9.
• Sweet corn — peak window zones 5-7; pick in the cool of morning and chill or process within an hour.
• Summer squash, zucchini, cucumbers — daily picking continues.
• Pole and bush beans — every 2-3 days.
• Tomatillos, eggplant — peak in zones 6-9.
• Melons — watermelon and cantaloupe peak zones 5-9. Cantaloupe slips from the vine when ripe; watermelon needs a hollow thump and yellow ground spot.
• Stone fruit — late peaches, nectarines, plums, prune plums.
• Brambles — late summer raspberries, early fall raspberry primocane crop, blackberries.
• Sweet onions, shallots, garlic (zone 5) — pull as tops fall over.
• Potatoes — early and mid-season varieties from May plantings. Wait until plant tops have died back fully for storage potatoes.
• First Asian pears and apples in the South and warm West.
• Basil, oregano, thyme, sage, parsley — cut and dry for winter storage.

Order and prep for September

• Garlic for fall planting — final ordering window before the September stock-thinning. Hardneck (Music, German White, Chesnok Red, German Extra Hardy) for zones 3-7; softneck (Silverskin, Inchelium Red, California Early) for zones 7+. See when to plant garlic.
• Spring bulbs — tulip, daffodil, hyacinth, allium, crocus catalogs shipping. Order before September stockouts.
• Bare-root strawberries, raspberries and asparagus crowns for fall delivery in zones 6+.
• Cover crop seed — winter rye, hairy vetch, crimson clover, oats and field peas for September sowing in cold zones.
• Cold frames, low tunnels, row cover — for season extension on September fall sowings.
• Plant labels and a fall sowing notebook — track what worked this summer for next year's planning.

Quick wins — five-minute August tasks

• Order garlic this weekend if you have not.
• Take a 4 in cutting of any tender perennial (pelargonium, fuchsia, salvia, coleus) before frost. Root in water on the kitchen windowsill.
• Tuck row cover over freshly sown fall salad to keep birds off seed and soil cool.
• Crush squash bug eggs every Sunday — they look like bronze BBs in clusters on leaf undersides.
• Pick zucchini before bedtime; a missed day is a bat.
• Refresh the bird bath daily through hot dry weeks.
• Bag any blighted tomato leaves for trash, not compost.

Related articles

• July garden tasks US — last month's job list
• September garden tasks US — what comes next
• When to plant garlic — fall planting timing by zone
• Mulching guide — depth, material and timing
• Powdery mildew and spider mites
• Frost date calculator, zone finder, USDA hardiness zone map

Reviewed and updated by the Growli editorial team. For questions about anything here, open Growli and ask — or email hello@getgrowli.app.