When to plant hardneck garlic in St. Louis

How to grow Hardneck garlic St. Louis climate

Where are you growing?

Comfortable

Hardneck garlic in St. Louis is a good fit outdoors. Planted in autumn, harvested next summer (about 7–9 months).

When to plantOctober 6 – November 16

Harvest: 210–270 days from planting
Season vs crop: 312 grow days vs 210–270 needed
Typical frost (last spring – first fall): April 18 – November 2

Hardneck garlic in St. Louis is a good fit outdoors. Planted in autumn, harvested next summer (about 7–9 months).

Planting conditions

Direct sow

Local activity windows for this place and growing method. Blue fill is usually too cold for this plant. Dashed lines are typical last and first frost.

Suitable growing days in a row312

Days to harvest210–270 days from planting

Oct 6 – Nov 16

Direct sow

Activity	Window	Notes
Direct sow	Oct 6 – Nov 16	Plant outdoors in this window.

Blue fill is usually too cold for this plant. Dashed lines are typical last and first frost. Adjust a week or two for your conditions.

Planting and growing across the year

Planting is the sow / plant-out window. Growing is daytime air versus this plant’s ideal (63 – 73 °F) and tolerable (23 – 86 °F) ranges.

Planting uses sow / plant-out rules (frost, soil germination, night, and last-sow): green when plantable, blue diagonal when nights or soil are too cold, amber cross-hatch when too hot, faint for other calendar limits. Growing shows daytime air against this plant’s ideal and tolerable ranges across the year.

Key dates

Typical last spring frostApril 18

Safer last spring frostApril 18

Typical first fall frostNovember 2

Safer first fall frostNovember 2

Frost-free days197

Outdoor sow dateOctober 6

Direct sow windowOctober 6 – November 16

Suitable growing windowOctober 6 – August 13 (312 days)

How these dates are judged

Ideal conditions: Daytime air from 63 – 73 °F.
Suitable conditions: Daytime air from 23 – 86 °F.
Last frost and first frost: Typical spring and fall frost dates for St. Louis, shown in the key dates.
Days to harvest: 210–270 days from planting, from typical days to harvest.
Sowing window: Dated sow and harvest bars use frost dates, soil minima, night limits, and last-sow count-back from typical crop timing. The year strip and weekly chart use the same window: air ratings only colour weeks inside it.

Growing window for Hardneck garlic: Oct 6 – Aug 13 (312 days)

Planting window for Hardneck garlic: Oct 6 – Nov 16 (42 days)

Outdoors: weekly temperatures and windows

Temperatures across the year for St. Louis. Shaded bands are this plant’s ideal and tolerable daytime air ranges. Growing is daytime air suitability; Planting is sow / plant-out conditions (same colour language). Window brackets mark each stretch.

Ideal range
Tolerable range
Possible min to max
Average min to max
Suitable
Tolerable
Too cold
Too hot

Selected week · tap a week or use the arrows

Week 1 · Jan 1 – Jan 4

Average 31 to 44 °F · Possible 16 to 66 °F

Growing: tolerable

Planting: too cold

A week is in range when its average low and high sit inside the tolerance band 23 to 86 °F; it is suitable when that average range also overlaps the ideal 63 to 73 °F band and possible readings stay within 23 °F to 86 °F. Crossing a possible limit, or missing the ideal band, makes it tolerable; a possible low below 23 °F makes it tolerable. When a sowing window is calculated, weeks outside that window are uncoloured even if air is in range.

Based on average frost dates.

Show all 53 weeks

Cover method weekly charts

Outdoor weekly chart is above. Open a cover chart only if you grow under fleece, a cold frame, or an unheated greenhouse.

Other plants for St. Louis

Calculated by Plan & Plant · Method · Data 2019–2026

Frost and suitability dates are typical figures from climate statistics. Microclimates vary; they are not a guarantee.

How we calculated this

Data: ERA5-Land via Open-Meteo, cell 38.63, -90.20, years 2019–2026 (not a 30-year climate normal yet).
Typical and safer dates: Typical last frost is the date after which half of winters in this sample had no more frost; safer is later in the sample so fewer winters still frosted.
Crop rule: Local windows for Hardneck garlic from frost dates, temperature ratings, and crop timing rules.
Confidence: Provisional — short or thin sample for this place.
Full methodology (algorithm 2026-10-season-6).

Report a problem