My Planting Calendar

What to plant in August in Illinois

In Illinois (IL), August is the heart of the growing season - about 17 weeks after the last frost (April 20) and 9 weeks before the first (October 14). The state averages 177 frost-free days a year (last frost April 20, first frost October 14; USDA zones 5a, 5b, 6a, 6b, 7a).

32 crops have a sowing or planting window this month, including bush bean, carrot, kale, radicchio, collard greens, endive & escarole - and 10 of those windows close during August.

Dates here come from Illinois frost dates (last frost Apr 20, first frost Oct 14). For one crop in detail, see when to plant bush bean, carrot or kale in Illinois.

Peak growing seasonSow or plant: 32Start indoors: 0Harvesting: 26

Illinois: planting activity through the year

1
24
70
86
58
11
24
32
8
2
2
0
JanFebMarAprMayJunJulAugSepOctNovDec
Frost riskFrost-free: Apr 20 – Oct 14
Bars count the vegetables, herbs and fruit with a sowing or planting window in each month, from the state’s average frost dates. 32 have one in August; the busiest month is April (86).

Last chance in August

Bush Bean (sow for a fall crop, by Aug 5) · Carrot (sow for a fall crop, by Aug 5) · Kale (sow for a fall crop, by Aug 5) · Radicchio (sow for a fall crop, by Aug 5) · Collard Greens (sow for a fall crop, by Aug 12) · Endive & Escarole (sow for a fall crop, by Aug 12) · Napa Cabbage (sow for a fall crop, by Aug 12) · Parsley (sow for a fall crop, by Aug 12) · Pea (sow for a fall crop, by Aug 12) · Swiss Chard (sow for a fall crop, by Aug 12)

For fall and winter harvests (30)

Sowings counted back from Illinois's first fall frost, so the crop matures before the cold - or, for garlic and similar, planted after it.

CropWhat to doWindowThis month
Bush BeanSow for a fall cropJul 19 – Aug 5Last chance - ends Aug 5
CarrotSow for a fall cropJul 19 – Aug 5Last chance - ends Aug 5
KaleSow for a fall cropJul 19 – Aug 5Last chance - ends Aug 5
RadicchioSow for a fall cropJul 19 – Aug 5Last chance - ends Aug 5
Collard GreensSow for a fall cropJul 26 – Aug 12Last chance - ends Aug 12
Endive & EscaroleSow for a fall cropJul 26 – Aug 12Last chance - ends Aug 12
Napa CabbageSow for a fall cropJul 26 – Aug 12Last chance - ends Aug 12
ParsleySow for a fall cropJul 26 – Aug 12Last chance - ends Aug 12
PeaSow for a fall cropJul 26 – Aug 12Last chance - ends Aug 12
Swiss ChardSow for a fall cropJul 26 – Aug 12Last chance - ends Aug 12
BeetSow for a fall cropAug 2 – Aug 19Aug 2 – Aug 19
Cilantro / CorianderSow for a fall cropAug 2 – Aug 19Aug 2 – Aug 19
Bok Choy / Pak ChoiSow for a fall cropAug 9 – Aug 26Aug 9 – Aug 26
BorageSow for a fall cropAug 9 – Aug 26Aug 9 – Aug 26
DillSow for a fall cropAug 9 – Aug 26Aug 9 – Aug 26
Fava Bean (Broad Bean)Sow for a fall cropAug 9 – Aug 26Aug 9 – Aug 26
Green Onion / ScallionSow for a fall cropAug 9 – Aug 26Aug 9 – Aug 26
KohlrabiSow for a fall cropAug 9 – Aug 26Aug 9 – Aug 26
LettuceSow for a fall cropAug 9 – Aug 26Aug 9 – Aug 26
Mache (Corn Salad)Sow for a fall cropAug 9 – Aug 26Aug 9 – Aug 26
MizunaSow for a fall cropAug 9 – Aug 26Aug 9 – Aug 26
Rapini (Broccoli Raab)Sow for a fall cropAug 9 – Aug 26Aug 9 – Aug 26
ChervilSow for a fall cropAug 16 – Sep 2Opens Aug 16
Mustard GreensSow for a fall cropAug 16 – Sep 2Opens Aug 16
SpinachSow for a fall cropAug 16 – Sep 2Opens Aug 16
TatsoiSow for a fall cropAug 16 – Sep 2Opens Aug 16
TurnipSow for a fall cropAug 16 – Sep 2Opens Aug 16
ArugulaSow for a fall cropAug 23 – Sep 9Opens Aug 23
WatercressSow for a fall cropAug 23 – Sep 9Opens Aug 23
RadishSow for a fall cropAug 30 – Sep 16Opens Aug 30

Keep sowing (succession)

Repeat sowings of crops already in the ground, for a steady harvest instead of a glut.

Harvesting in August

First harvests expected this month from crops sown or planted on time earlier in the season.

Potato · Jun 15 – Aug 4Sweet Corn · Jun 26 – Aug 5Bell Pepper · Jul 3 – Aug 2Southern Pea (Cowpea) · Jul 3 – Aug 2Brussels Sprouts · Jul 5 – Aug 4Sunflower · Jul 6 – Aug 5Lima Bean · Jul 8 – Aug 7Edamame (Soybean) · Jul 11 – Aug 5Tomatillo · Jul 11 – Aug 5Chili Pepper · Jul 13 – Aug 12Cantaloupe / Muskmelon · Jul 13 – Aug 2Watermelon · Jul 13 – Aug 12Eggplant · Jul 15 – Aug 4Leek · Jul 15 – Sep 3Winter Squash · Jul 16 – Aug 15Parsnip · Jul 22 – Aug 21Salsify · Jul 25 – Sep 3Pumpkin · Jul 26 – Aug 25Rosemary · Jul 26 – Aug 25Celery · Jul 29 – Sep 7Celeriac · Jul 29 – Aug 18Luffa (Loofah Gourd) · Aug 2 – Oct 1Peanut · Aug 5 – Sep 24Sweet Potato · Aug 9 – Sep 8Zucchini / Summer Squash · Aug 26 – Sep 27Cucumber · Aug 31 – Oct 7

Planting dates for popular crops in Illinois

Every crop has its own full-year dates for Illinois: indoor start, transplant or direct sowing, and harvest.

When to plant bush bean in Illinois →When to plant carrot in Illinois →When to plant kale in Illinois →When to plant pea in Illinois →When to plant swiss chard in Illinois →When to plant beet in Illinois →When to plant lettuce in Illinois →When to plant spinach in Illinois →Illinois frost dates by zone →

Peak growing season: August garden jobs in Illinois

  1. Water deeply two or three times a week rather than a little every day - about an inch a week, more in heat. See watering a vegetable garden.
  2. 9 weeks until the average first frost (October 14). Fall crops start now: bush bean, carrot, kale, radicchio. See the fall and winter garden guide.
  3. Check the undersides of leaves twice a week - catching pests early is most of the battle (pest identification guide).
  4. Harvest often: potato, sweet corn, bell pepper, southern pea (cowpea) should be coming in. Picking regularly keeps beans, squash and cucumbers producing.

USDA zone chart for Illinois

Illinois spans USDA zones 5a, 5b, 6a, 6b, 7a. Colder zones, usually higher or further inland, have a later last spring frost and an earlier first fall frost than the state average.

ZoneLast frostFirst frostSeason
Zone 5Apr 30Oct 5160 days
Zone 6Apr 15Oct 15185 days
Zone 7Apr 5Oct 25200 days

Questions gardeners ask

What vegetables can I plant in Illinois in August?

32 crops have a window in August: bush bean, carrot, kale, radicchio, collard greens, endive & escarole, napa cabbage, parsley, pea, swiss chard and more. The tables above give the exact dates for each.

Is it too late to plant garlic in Illinois in August?

Not too late - it's actually a little early. In Illinois the next garlic window opens around October 25: plant in fall, after first frost.

Is it too late to plant tomatoes in Illinois in August?

For this year, yes - the tomato windows in Illinois have closed. The next step is to start seeds indoors from about February 23.

When is the first frost in Illinois?

The statewide average first fall frost is around October 14 and the last spring frost around April 20. Your town can be a week or two either side - look yours up by ZIP code.

What can I harvest in Illinois in August?

From plantings made on time: potato, sweet corn, bell pepper, southern pea (cowpea), brussels sprouts, sunflower, lima bean, edamame (soybean), tomatillo, chili pepper.

← July in IllinoisSeptember in Illinois →Full-year Illinois planting calendar →Illinois frost dates →

What to plant in August in other states

IndianaIowaMichiganMinnesotaMissouriOhioWisconsinAlabamaAll states →

Dates are computed from Illinois’s statewide average frost dates (from NOAA/NCEI climate normals) and each crop’s timing in our crop database. Your garden may be a week or two either side - for dates tuned to your ZIP code, use the planting calendar.