When to plant pumpkin in Portsmouth

In Portsmouth, typical last spring frost is March 23 and typical first fall frost is December 1. Typical last spring frost: March 23. Pumpkin in Portsmouth is not realistic outdoors: 0 suitable days are fewer than the 90 days this plant usually needs.

Pumpkin

How to grow Pumpkin Portsmouth climate Weekly temperatures and windows

Where are you growing?

Not realistic outdoors

Not realistic in a cold frame

Pumpkin in Portsmouth is not realistic outdoors: 0 suitable days are fewer than the 90 days this plant usually needs.

When to plantJune 18 – July 1

Harvest: September 16 – November 17
Season vs crop: 0 grow days vs 90–120 needed
Typical frost (last spring – first fall): March 23 – December 1

Pumpkin in Portsmouth is not realistic outdoors: 0 suitable days are fewer than the 90 days this plant usually needs.

Cover methods on this page (fleece, cold frame, unheated greenhouse) do not add enough season for this crop here. Pick another plant from the list below, or use a heated greenhouse.

Planting conditions

Direct sow
Grow outdoors
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 row0

Days to harvest90–120 days from seed

No planting window is recorded for this place.

Too cold
Frost line

Blue fill is usually too cold for this plant. Dashed lines are typical last and first frost (35 seasons (1991–2025)). 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 (21 – 35 °C70 – 95 °F21 – 35 °C (70 – 95 °F)) and tolerable (16 – 38 °C61 – 100 °F16 – 38 °C (61 – 100 °F)) ranges.

Ideal / plantable
Tolerable
Too cold
Too hot
Outside window

Planting uses sow / plant-out rules; growing shows daytime air against this plant’s ideal and tolerable ranges.

Key dates

Typical last spring frostMarch 23

Low-risk last spring frostApril 14

Typical first fall frostDecember 1

Low-risk first fall frostNovember 17

Frost-free days252

Outdoor sow dateJune 18

Direct sow windowJune 18 – July 1

Suitable growing window – (0 days)

Expected harvestSeptember 16 – November 17

How these dates are judged

Ideal conditions: Daytime air from 21 – 35 °C70 – 95 °F21 – 35 °C (70 – 95 °F).
Suitable conditions: Daytime air from 16 – 38 °C61 – 100 °F16 – 38 °C (61 – 100 °F).
Last frost and first frost: Typical spring and fall frost dates for Portsmouth, shown in the key dates.
Days to harvest: 90–120 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. Air ratings on the weekly chart colour only weeks inside that same window — see weekly temperatures and windows.

Other plants for Portsmouth

Calculated by Plan & Plant. Method. Data 35 seasons (1991–2025).

Frost and suitability dates are typical figures from climate statistics.

Based on 35 years (1991–2025) of ERA5-Land data from Open-Meteo, for an area of about 10 km. Typical dates, not a guarantee.

Dates for Portsmouth use ERA5-Land cell 50.80, -1.09. How we calculated this · Algorithm 2026-10-season-10.

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