Gardening in Saint Louis
Missouri · Central Hardwoods & Interior Plateaus · hardiness zone 7a
Fall · September 14, 2026
Saint Louis, Missouri
Now
28°C · Clear
Today
31° / 17°
Soil 6 cm
25°C
First frost
~49 days (Nov 2)
Above about 32 °C tomatoes drop their flowers and lettuce turns bitter.
- Ruby-throated hummingbirdbest now — Feeding hardest in the first and last hour — it burns through the night's reserves by dawn and must refuel before dark.
- Green lacewingbest now — Adults fly at dusk and through the night; the larvae hunt around the clock and do the real work.
In the garden now · September
Who else is working the garden
The insects and soil life out near Saint Louis, Missouri in September. Most of them are on your side — learn the few that aren't before you reach for anything.
PollinatorMay–OctMonarch butterfly
Danaus plexippus
Orange with heavy black veins and a white-spotted black border. The caterpillar is banded yellow, white and black.
What it does in the garden →Photo: Christine Young · CC BY 4.0
PollinatorMay–SepRuby-throated hummingbird
Archilochus colubris
Tiny, iridescent green above; the male has a black-looking throat that flares ruby in the right light.
Writing your field guide — reading the forecast, the moon and the map…
Overhead · Saint Louis, Missouri
The sky over the garden
The two clocks nothing on the ground can argue with: the length of the day, and the phase of the moon.
The sun
12h 27m of light
Sunrise
06:42
Solar noon
12:55
Sunset
19:09
A month from now the day will be 1h 14m shorter. Enough light for steady growth.
Right now · Saint Louis, Missouri
Forces at work
Nothing here is a guess. Each of these is read from this week's forecast and this location's climate record, and each one is pushing the season one way or the other.
- Quiet right now
Frost
203 frost-free days
Typically Apr 13 to Nov 2 here. Coldest night in the next week: 16.7 °C.
The hard edge of the growing season. Ice inside a leaf ruptures its cells — one night ends a tomato and sweetens a parsnip.
- Working for you
Soil warmth
24.7 °C
Warm enough for beans, corn, squash, cucumber and transplanted tomato and pepper. Roots run hard at this temperature.
Seeds read soil temperature, not the calendar. Six centimetres down is where the decision gets made.
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