When to plant sweet corn in Boston

Where are you growing?

Comfortable

Tight fit in greenhouse

Comfortable in a cold frame

Sweet corn in Boston is a good fit outdoors. The suitable growing window of 134 days covers the 60–90 days this plant usually needs.

When to plantMay 13 – July 20

Harvest: July 12 – September 23
Season vs crop: 134 grow days vs 60–90 needed
Typical frost (last spring – first fall): April 25 – October 30

Sweet corn in Boston is a good fit outdoors. The suitable growing window of 134 days covers the 60–90 days this plant usually needs.

Planting conditions

Direct sow
Harvest

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 row134

Days to harvest60–90 days from seed

May 13 – Jul 20

Direct sow

Jul 12 – Sep 23

Harvest

Activity	Window	Notes
Direct sow	May 13 – Jul 20	Plant outdoors in this window.
Harvest	Jul 12 – Sep 23	Expected harvest from typical days to harvest.

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 (70 – 90 °F) and tolerable (55 – 95 °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 25

Safer last spring frostApril 25

Typical first fall frostOctober 30

Safer first fall frostOctober 30

Frost-free days187

Outdoor sow dateMay 13

Direct sow windowMay 13 – July 20

Suitable growing windowMay 13 – September 23 (134 days)

Expected harvestJuly 12 – September 23

How these dates are judged

Ideal conditions: Daytime air from 70 – 90 °F.
Suitable conditions: Daytime air from 55 – 95 °F.
Last frost and first frost: Typical spring and fall frost dates for Boston, shown in the key dates.
Days to harvest: 60–90 days from seed, 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 Sweet corn: May 13 – Sep 23 (134 days)

Planting window for Sweet corn: May 13 – Jul 20 (69 days)

Usually too cold: Jan 1 – May 10; Sep 28 – Dec 31

Outdoors: weekly temperatures and windows

Temperatures across the year for Boston. 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 20 · May 11 – May 17

Average 50 to 69 °F · Possible 37 to 83 °F

Growing: too cold (inside window)

Planting: suitable

A week is in range when its average low and high sit inside the tolerance band 55 to 95 °F; it is suitable when that average range also overlaps the ideal 70 to 90 °F band and possible readings stay within 32 °F to 95 °F. Crossing a possible limit, or missing the ideal band, makes it tolerable; any chance of frost (possible low below 32 °F) makes it too cold. 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 Boston

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 42.40, -71.10, 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 Sweet corn 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).

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