This calendar is set for St. Charles County, Missouri, and works for most of the St. Louis area. Two dates anchor it, both medians from the National Weather Service (1991–2020):
- Last spring freeze: around April 10 in St. Charles (April 2 at St. Louis Lambert airport)
- First fall freeze: around October 18 in St. Charles (November 1 at Lambert)
Half the years are later, half earlier, so watch the forecast.
Each packet in the Missouri Native Series also carries a postmark with its best sowing season: SOW DEC–FEB (winter), SOW MAR–MAY (spring) or SOW SEP–NOV (fall).
January
Sow: Anything with a winter postmark, in jugs or on bare ground. Start with the 60-day seeds (Nos. 2, 9, 10 and 12) so they get their full chill. Do: Set jugs where rain and snow reach them. Check them in long dry spells. Plan ahead: If you’d rather sow in spring, 60-day seeds go in the fridge by about February 9.
February
Sow: Get the 60-day seeds outside by mid-February. The 30-day seeds (Nos. 3, 4, 5, 6 and 8) can go out through month’s end. Do: Start 60-day fridge batches by about February 9 for an April 10 sowing.
March
Sow: Wild Bergamot (No. 7) and Purple Coneflower (No. 1) on bare, moist soil. Neither needs a chill. Do: Open winter-sowing jugs on warm days; close them on cold nights. Start 30-day fridge batches by about March 11. Seed Club: Spring mailing arrives.
April
Sow: Fridge-stratified seed, after the last frost. Do: Move jug seedlings with one or two sets of true leaves into the garden after hardening them off for a week. Mark where milkweeds were sown; they’re slow to appear. In bloom: Golden Alexanders (No. 12).
May
Sow: Wild Bergamot (No. 7), if you haven’t yet. Do: Water new seedlings during dry spells and pull weeds around them. First-year natives put their energy into roots, so small tops are normal. In bloom: Purple Coneflower, Ozark Coneflower, Common Milkweed, Lanceleaf Coreopsis, Missouri Evening Primrose and Golden Alexanders.
June
Do: Water first-year plants in long dry spells. Look for monarch caterpillars on milkweed, and leave chewed leaves alone. In bloom: The busiest month of the series: Nos. 1, 2, 3, 4, 5, 6, 7, 8, 11 and 12. Seed Club: Summer mailing arrives (milkweed seed to hold for late-fall sowing).
July
Do: Keep watering first-year plants in dry spells. Deadhead Black-eyed Susan and Lanceleaf Coreopsis if you want more flowers or fewer volunteers, but leave some seed heads for the birds. Aphids on milkweed? Leave them for ladybugs or rinse them off. In bloom: Purple Coneflower, Ozark Coneflower (finishing), Black-eyed Susan, all three milkweeds, Wild Bergamot and Missouri Evening Primrose.
August
Do: Pinch New England Aster one last time before August 15 to keep it compact. Choose bare, weed-free spots for fall and winter sowing. In bloom: Rough Blazing Star (No. 9) begins. Purple Coneflower, Black-eyed Susan, the milkweeds, Wild Bergamot and Missouri Evening Primrose carry on.
September
Sow: Fall-postmark seed: Missouri Evening Primrose (No. 11). Golden Alexanders (No. 12) and Lanceleaf Coreopsis (No. 8) can go out now too. Watch: Monarch numbers peak in Missouri in mid-September. Look for them on New England Aster. In bloom: Black-eyed Susan, Swamp Milkweed, Rough Blazing Star and New England Aster. Seed Club: Fall mailing arrives.
October
Sow: Fall sowing continues as the weather cools. Do: Leave seed heads standing for goldfinches and other birds, and leave stems for overwintering insects. Stem-nesting bees use the hollow stems of plants like Wild Bergamot. In bloom: Rough Blazing Star and New England Aster.
November
Sow: Once the soil is cold, scatter winter-postmark seed on bare, firm, weed-free ground and press it in. It will wait for spring. Do: Keep unsown packets cool and dry.
December
Sow: Winter sowing season opens. Many gardeners start their jugs around the winter solstice. Do: Save gallon jugs for January. Seed Club: Winter mailing arrives, right on time for winter sowing.
Sources: National Weather Service St. Louis, frost/freeze normals 1991–2020; Prairie Moon Nursery, germination codes; Missouri Department of Conservation, Xplor (Sept. 2022) and Field Guide entries; Grow Native! (New England Aster pinching); NC State Extension (stem-nesting bees on Monarda fistulosa); University of Wisconsin–Madison Extension and University of Illinois Extension on winter sowing. Bloom months come from our species data, which cites the Missouri Department of Conservation and Grow Native! first. Full links in our sources list.