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Portsmouth Frost Dates & Growing Season
Here's the frost forecast for the next three days (last updated on December 8th, 2025 6:05 AM).
Dec 8th
Safe
Dec 9th
Safe
Dec 10th
Safe
Last Frost Date (Spring)
The average last frost date for Portsmouth is March 20th. We recommend waiting until April 3rd before planting tender crops outdoors.
First Frost Date (Autumn)
The average first frost date for Portsmouth is December 5th.
Growing Season
Based on historical data, the growing season in Portsmouth is approximately 260 days long.
Portsmouth Planting Calendar
This weekly planting calendar displays the ideal windows for starting seeds, transplanting, and harvesting.
Portsmouth Monthly Gardening Guide
January
In January, you can start Aubergine indoors, start Geranium indoors, start Petunia indoors, start Coleus indoors, and start Thyme indoors.
February
In February, you can sow Lettuce outside, sow Poppy outside, sow Carrot outside, sow Pea outside, and sow Chives outside.
March
In March, you can sow Gladiolus outside, sow Hollyhock outside, sow Fenugreek outside, sow Babys Breath outside, and sow Hyssop outside.
April
In April, you can sow Watermelon outside, sow Okra outside, sow Black Bean outside, sow Melon outside, and sow Corn outside.