When to Plant Brussels Sprouts in St. Louis, MO
Published: April 24, 2026
Brussels Sprout Planting Dates for St. Louis, MO
| Start seeds indoors | February 15–22 |
| Last frost (average) | March 22 |
| Transplant outdoors | June 14–24 |
| Minimum soil temperature | 45°F |
| Expect first harvest | September 2 – September 22 |
| Fall crop planting | August 11–21 |
| Fall crop harvest | October 30 |
| First fall frost (average) | November 10 |
⚠ Brussels sprouts are planted in midsummer for a fall harvest. Count back 90 days from your first fall frost to find the transplant date. Start seeds indoors 4–6 weeks before that date. Flavor improves after frost.
Best Brussels Sprout Varieties for St. Louis, MO
Consult a St. Louis-area nursery or your state extension office for brussels sprout varieties proven in Zone 6b.
Growing Brussels Sprouts in St. Louis
St. Louis sits in Zone 6b, with an average last frost of March 22 and first fall frost around November 10 — giving a 233-day frost-free growing season. Cool-season crops like brussels sprout benefit from St. Louis's cooler spring and fall windows, when temperatures stay in the 55–75°F sweet spot that produces the best flavor and least bolting.
St. Louis's moderate climate supports brussels sprout on the standard transplant calendar with minimal special accommodation. Succession planting — sowing fresh seeds or setting new transplants every 2–3 weeks through spring — stretches the harvest window and gives you a backup crop if pests hit the first planting.
St. Louis's clay-loam soils are productive but benefit from annual compost amendment — 2 to 3 inches worked in before planting improves drainage and nutrient availability for brussels sprout. Consistent watering (1.5 inches per week) paired with organic mulch maintains the even moisture that clay-loam holds well. Avoid working wet soil in spring, which causes severe compaction in clay-loam blends.
Brussels Sprout Calendar for St. Louis
| Month | Task |
|---|---|
| February | Start seeds indoors under grow lights |
| March | Last frost — harden off seedlings outdoors |
| June | Transplant outdoors into warm soil |
| September | Expect first harvest window to open |
| August | Start fall crop — transplants or direct sow |
| November | First fall frost — harvest remaining, end of outdoor season |
Brussels Sprout Tips for St. Louis Gardeners
- •Count back 90 days from first fall frost to find the transplant date — this is the most important Brussels sprout timing rule.
- •Pinch the top of each plant about a month before first frost — this channels energy into sprout formation.
- •Succession plant brussels sprout in St. Louis every 2–3 weeks through spring to extend the harvest window into summer.
Common Brussels Sprout Pests in St. Louis
- •Cabbage Worm — peaks July in Zone 6b (active May–September); green caterpillars on brassicas; apply Bt spray or use row covers.
- •Aphid — peaks July in Zone 6b (active May–September); monitor closely during peak season and treat early.
- •Cabbage Looper — peaks July in Zone 6b (active May–September); loop-walking green caterpillars; Bt spray works well.
Check plants every 2–3 days during peak season — early intervention prevents most infestations from becoming serious.
What to Plant with Brussels Sprouts in St. Louis
In St. Louis's moderate climate, Onion and Celery are the most beneficial plants to grow alongside brussels sprout. Onion deters carrot fly, aphids, and several root-zone pests through sulfur compounds. Keep brussels sprout away from Tomato — it competes for nutrients or shares pest pressure.
Frequently Asked Questions
When should I plant brussels sprout in St. Louis, MO?
In St. Louis (Zone 6b), start brussels sprout seeds indoors around February 15–22 and transplant outdoors around June 14–24. The city's average last frost of March 22 is the anchor date — count 5 weeks back for seed starting and 12 weeks forward for transplanting.
What zone is St. Louis, MO for brussels sprout growing?
St. Louis is USDA Zone 6b. For brussels sprout, this means a frost-free growing season of roughly 33 weeks running from March 22 to November 10. Cool-season crops like brussels sprout thrive in this zone with both spring and fall planting windows available.
When is brussels sprout harvest season in St. Louis?
Expect the first brussels sprout harvest in St. Louis around September 2, with harvest continuing through September 22. This is based on 80–100 days from transplant or direct sow. A fall crop planted August 11–21 adds a second harvest around October 30.
How long does it take to grow brussels sprout in St. Louis, MO?
From transplant or direct sow to first harvest, brussels sprout takes 80–100 days in St. Louis's climate. Based on a typical planting date of June 14–24, expect your first harvest around September 2. St. Louis's Zone 6b transition-zone climate produces maturity times right in the middle of the stated range.
What soil does brussels sprout need in St. Louis?
St. Louis's clay-loam soil is productive for brussels sprout but benefits from annual compost amendment. Work 2–3 inches of compost into the top 10 inches before planting. Avoid working wet soil in spring — clay-loam compacts badly when wet. Consistent watering paired with organic mulch maintains the even moisture these soils hold well.