O'Fallon, Missouri planting calendar and frost dates
O'Fallon is in USDA hardiness zone 6b. The last spring frost typically comes around April 10 and the first fall frost around October 26, giving about 199 frost-free days a year.
- Hardiness zone
- Zone 6b
- Typical last frost
- April 10
- Typical first frost
- October 26
- Frost-free season
- 199 days
Frost dates in O'Fallon
Last spring frost
- March 26Risky: frost later than this in 9 years out of 10
- April 10Typical: a later frost in half of years
- April 26Safe: a later frost only 1 year in 10
First fall frost
- October 12Risky: frost earlier than this 1 year in 10
- October 26Typical: an earlier frost in half of years
- November 8Late: frost before this in 9 years out of 10
The growing season between the typical last and first frosts is about 199 days. Frost here means a low of 32°F at the weather station. A hard freeze (28°F), which damages most hardy crops too, typically ends around March 31 and returns around November 5.
NOAA U.S. Climate Normals 1991-2020 for Weldon Spring Nws, 11.2 miles SSE of the city center and 129 feet higher. Low-lying and rural spots often frost later in spring and earlier in fall than airports and city centers.
What to plant each month in O'Fallon
January
Start indoors: broccoli, cabbages, cauliflower, collard greens, kale, leeks, onions, oregano, parsley, petunias, ranunculus, rosemary, snapdragons
February
Start indoors: black-eyed susans, broccoli, cabbages, cauliflower, celery, chives, cilantro, collard greens, eggplants, ginger, kale, leeks, lettuce, marigolds, nasturtiums, oregano, parsley, peppers, petunias, ranunculus, rosemary, sage, snapdragons, spinach, swiss chard
Plant or sow outdoors: black-eyed susans, blueberries, garlic, grapes, grass seed, hollyhocks, onions, peas, poppies, raspberries, rhubarb, strawberries, turnips, wildflowers
March
Start indoors: basil, cantaloupes, celery, cilantro, eggplants, marigolds, nasturtiums, peppers, ranunculus, spinach, swiss chard, tomatoes, watermelons
Plant or sow outdoors: beets, black-eyed susans, blackberries, blueberries, broccoli, cabbages, carrots, cauliflower, chives, cilantro, collard greens, dahlias, dill, figs, garlic, gladioli, grapes, grass seed, hollyhocks, kale, leeks, lettuce, onions, parsley, peas, poppies, radishes, ranunculus, raspberries, rhubarb, roses, snapdragons, spinach, strawberries, swiss chard, turnips, wildflowers
April
Start indoors: cantaloupes, cosmos, cucumbers, okra, pumpkins, watermelons, winter squash, zucchini
Plant or sow outdoors: asparagus, basil, beets, cantaloupes, carrots, cauliflower, chives, cilantro, cucumbers, dahlias, dill, eggplants, figs, garden mums, ginger, gladioli, grapes, green beans, green onions, kentucky bluegrass, lavenders, leeks, lettuce, lilies, marigolds, mints, nasturtiums, oregano, parsley, peppers, perennial ryegrass, petunias, potatoes, pumpkins, ranunculus, rosemary, roses, sage, snapdragons, spinach, sunflowers, sweet corn, sweet peas, swiss chard, tall fescue, thyme, tomatoes, watermelons, winter squash, zucchini
May
Start indoors: zinnias
Plant or sow outdoors: asparagus, basil, bermudagrass, cantaloupes, celery, centipedegrass, cosmos, cucumbers, eggplants, garden mums, ginger, green beans, green onions, okra, peanuts, peppers, pumpkins, st. augustinegrass, sunflowers, sweet potatoes, tomatoes, watermelons, winter squash, zoysiagrass, zucchini
June
Plant or sow outdoors: bermudagrass, centipedegrass, green onions, okra, st. augustinegrass, zinnias, zoysiagrass
July
Plant for fall: brussels sprouts, collard greens, lettuce, swiss chard
August
Plant for fall: azaleas, bearded irises, beets, broccoli, cabbages, carrots, cauliflower, clematis, collard greens, coneflowers, daylilies, hostas, hydrangeas, kale, lettuce, peas, radishes, roses, saffron, snapdragons, spinach, swiss chard, turnips
September
Plant for fall: azaleas, bearded irises, beets, broccoli, cabbages, cauliflower, clematis, coneflowers, crocuses, daffodils, daylilies, grass seed, hostas, hyacinths, hydrangeas, kale, kentucky bluegrass, lilies, ornamental alliums, peonies, perennial ryegrass, radishes, roses, saffron, spinach, tall fescue, tulips, turnips
October
Plant for fall: crocuses, daffodils, daylilies, garlic, hyacinths, lilies, ornamental alliums, peonies, tulips
November
Plant for fall: crocuses, garlic, hyacinths, ornamental alliums, tulips
December
Start indoors: onions
Frost dates and zones by ZIP code in O'Fallon
O'Fallon's 4 main ZIP codes take their frost dates from 2 different NOAA stations: the typical last frost ranges from April 8 in 63376 to April 10 in 63368. Every one of them is in zone 6b.
Planting dates for popular crops in O'Fallon
| Plant | Start indoors | Plant or sow outdoors | Fall planting |
|---|---|---|---|
| Tomatoes | Mar 4 to 18 | Apr 29 to May 13 | — |
| Strawberries | — | Feb 27 to Mar 13 | — |
| Lettuce | Feb 13 to 27 | Apr 3 to 17 | Jul 27 to Aug 31 |
| Cilantro | Feb 27 to Mar 13 | Apr 10 to 17 | — |
| Basil | Mar 11 to 25 | Apr 29 to May 6 | — |
| Potatoes | — | Apr 2 to 9 | — |
| Garlic | — | Feb 27 to Mar 13 | Oct 26 to Nov 9 |
| Onions | Dec 19 to Jan 30 | Mar 13 to 27 | — |
| Cucumbers | Apr 1 to 15 | Apr 29 to May 13 | — |
| Pumpkins | Apr 1 to 15 | Apr 29 to May 13 | — |
| Peppers | Feb 11 to Mar 11 | Apr 29 to May 13 | — |
| Carrots | — | Mar 20 to Apr 10 | Aug 3 to 24 |
| Sweet Potatoes | — | May 17 to 24 | — |
| Watermelons | Mar 25 to Apr 8 | Apr 29 to May 13 | — |
| Sweet Corn | — | Apr 10 to 24 | — |
| Green Beans | — | Apr 29 to May 13 | — |
| Zucchini | Apr 1 to 15 | Apr 29 to May 13 | — |
| Broccoli | Jan 23 to Feb 13 | Mar 13 to 27 | Aug 10 to Sep 7 |
| Peas | — | Feb 27 to Mar 13 | Aug 3 to 17 |
| Spinach | Feb 27 to Mar 6 | Apr 3 to 17 | Aug 17 to Sep 21 |
| Sunflowers | — | Apr 10 to May 1 | — |
| Zinnias | May 6 to 13 | Jun 3 to 17 | — |
| Tulips | — | — | Sep 14 to Nov 9 |
| Daffodils | — | — | Sep 14 to Oct 26 |
| Grass Seed | — | Feb 27 to Mar 13 | Sep 14 to 28 |
Nearby cities
- St. Peters, MO zone 6b, last frost Apr 8
- St. Charles, MO zone 6b, last frost Apr 2
- Florissant, MO zone 7a, last frost Apr 2
- St. Louis, MO zone 7a, last frost Apr 8
- Columbia, MO zone 6b, last frost Apr 5
- Springfield, IL zone 6a, last frost Apr 14
Planting in MissouriAbout zone 6bPrintable calendar for O'Fallon
Questions
When is the last frost in O'Fallon?
Around April 10 in a typical year, based on NOAA's 1991-2020 records for Weldon Spring Nws. There is still a 1 in 10 chance of frost after April 26.
What planting zone is O'Fallon in?
USDA hardiness zone 6b (2023 map). The zone tells you which perennials survive the winter; planting dates depend on frost dates instead.
When should I plant tomatoes in O'Fallon?
Start seeds indoors March 4 to 18 and set plants out April 29 to May 13.
When is the first frost in O'Fallon?
Around October 26 in a typical year, and before October 12 about 1 year in 10.