Sweet Pea Sowing Calendar - The Best Months to Sow for Early Blooms & Long Stems (UK Guide)
- Jane Westoby
- Dec 7, 2025
- 3 min read
Sweet Peas are one of the most loved cut flowers in the UK — and one of the most misunderstood when it comes to timing. Should you sow in autumn? January? February? Is March too late? And what actually happens to the plants depending on the month you sow?
Here’s your UK-specific month-by-month sweet pea sowing calendar, so you can choose the perfect timing for your garden and get strong plants, earlier blooms, and long stems for cutting.
This guide works for all Sweet Pea varieties — Spencer types, heritage types, and the earlier-blooming Spring Sunshine series.
Autumn Sowing (Oct–Nov) - For the Earliest Flowers & Strongest Plants
Autumn sowing is the flower farmer’s secret weapon.
October
✔ Best month for early flowers
✔ Strong roots develop over winter
✔ Compact, sturdy seedlings
✔ Handles cold beautifully (hardy annual)
Expect: Flowers from late May to June, with long stems and exceptional productivity.
Needs: A cold frame, unheated greenhouse, polytunnel or porch — somewhere bright and cool.
November
✔ Still excellent for autumn sowers
✔ Plants start slower but catch up nicely
✔ Slightly later flowers than October sowings
Expect: Flowers from June.
Note: Light levels drop now → prevent leggy growth by keeping them cool rather than warm.
Winter Sowing (Dec–Jan) - Possible — but tricky
December
Low light = high risk of legginess
Only worth attempting if you have excellent light
Expect: Plants behave like slow January sowings.
Flowering still June–July.
Verdict: Fine for experienced growers with good conditions.
January
✔ Surprisingly good month
✔ Slow, compact growth
✔ Easy to manage indoors
✔ Perfect for beginners who missed autumn
Expect: Flowers in June–July. Strong stems. Very reliable timing.
Tip: A bright windowsill or unheated greenhouse is perfect — just avoid warm rooms.
Spring Sowing (Feb–May) - The Safest Window for Most Gardeners
February
THE BEST spring sowing month
✔ Ideal balance of daylight + cooler temperatures
✔ Strong, stocky seedlings
✔ Perfect for beginners
Expect: Flowers from late June–July.
Verdict: If you only sow once, sow in February.
March
✔ Still a great sowing month
✔ Especially good for new growers
✔ Slightly shorter flowering window than autumn sowings
Expect: Flowers from July–August.
Note: Provide good light to avoid stretching.
April
✔ Plants grow fast in warm weather
✔ Great for topping up your patch
Expect: Flowers from July–August.
Verdict: Works, but your season will be shorter.
May
✔ Last realistic sowing month
✔ Great for a late season crop
Expect: Flowers from late July–September
Verdict: Works, but your season will be shorter and later
When NOT to Sow Sweet Peas (June–September)
Avoid sowing Sweet Peas in summer.
Plants become:
stressed
short-stemmed
heat-stunted
late to flower (or don’t flower at all)
Sweet Peas need cool roots and rising spring light — not warm summer soil.
If it's June or later → wait until autumn.
So… When Should You Sow? Here’s the Quick Answer - your sweet pea sowing calendar
Growing Goal | Best Sowing Month |
Earliest flowers | Oct–Nov |
Strongest plants | Oct–Nov or Feb |
Longest cutting season | Autumn sow + February sow |
Beginner-friendly timing | February–March |
Simplest seedling care | Spring sowings |
Overwintering | October |
Both autumn and spring sowings work beautifully — you’re not late, and you’re not behind. You’re simply choosing the timing that fits your growing style.
Want Continuous Sweet Peas? Succession Sow
For a longer flowering season, sow:
once in autumn
again in February
Once again in May
You’ll cover early, mid, and late-season blooms — perfect for cut flowers or a long-lasting garden display.
Next Steps: Learn More About Growing Sweet Peas
To continue your journey:
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