When to plant fava bean 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. Fava bean in Portsmouth is a good fit outdoors. The suitable growing window of 298 days covers the 80–110 days this plant usually needs.

Fava bean

How to grow Fava bean Portsmouth climate Weekly temperatures and windows

Where are you growing?

Comfortable

Comfortable in greenhouse

Not realistic in a cold frame

Fava bean in Portsmouth is a good fit outdoors. The suitable growing window of 298 days covers the 80–110 days this plant usually needs.

When to plantMarch 3 – September 9

Harvest: May 22 – January 2
Season vs crop: 298 grow days vs 80–110 needed
Typical frost (last spring – first fall): March 23 – December 1

Fava bean in Portsmouth is a good fit outdoors. The suitable growing window of 298 days covers the 80–110 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 row298

Days to harvest80–110 days from seed

Mar 3 – Sep 9

Direct sow

May 22 – Jan 2

Harvest

Activity	Window	Notes
Direct sow	Mar 3 – Sep 9	Plant outdoors in this window.
Harvest	May 22 – Jan 2	Expected harvest from typical days to harvest.

Direct sow
Harvest

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 (15 – 21 °C59 – 70 °F15 – 21 °C (59 – 70 °F)) and tolerable (4 – 24 °C39 – 75 °F4 – 24 °C (39 – 75 °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 dateMarch 3

Direct sow windowMarch 3 – September 9

Suitable growing windowMarch 3 – December 25 (298 days)

Expected harvestMay 22 – January 2

How these dates are judged

Ideal conditions: Daytime air from 15 – 21 °C59 – 70 °F15 – 21 °C (59 – 70 °F).
Suitable conditions: Daytime air from 4 – 24 °C39 – 75 °F4 – 24 °C (39 – 75 °F).
Last frost and first frost: Typical spring and fall frost dates for Portsmouth, shown in the key dates.
Days to harvest: 80–110 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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