When Do You Plant Sweet Peas? (UK Guide)

You can plant sweet peas at several times of year, depending on whether you’re planting seeds or young plants, and how early you want flowers.

⭐ Recommended Products — Sweet Peas & Growing Essentials

Sweet peas are fragrant classics that bring colour and scent to summer gardens — and starting them right gives the best blooms.

• Sweet Pea Seed Mix (Classic & Fragrant Varieties)
A selection of popular and scented sweet pea seeds — perfect for sowing early under cover to produce tall, blooming plants later.
👉 Click here to see top options

• Sweet Pea Support Canes & Twine Kit
Strong bamboo canes with garden twine to train your sweet peas up for maximum display and air circulation.
👉 Click here to see top options

• Seed & Cutting Propagation Compost
Fine, free-draining compost ideal for sowing sweet peas — helps seedlings get a strong start with healthy roots.
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• Sweet Pea Grow Bags / Small Containers
Great for sowing seeds in pots, cold frames, or greenhouse benches before planting out — gives easy management of early seedlings.
👉 Click here to see top options

• Grow Lights or Heat Mat for Seed Starting
Provides extra light and warmth during early sowing if your natural light is limited — helps sweet peas germinate reliably.
👉 Click here to see top options

🌱 When to Plant Sweet Pea Seeds

Autumn (October–November)

• Sow seeds in pots under cover
• Produces the strongest plants with deep roots
• Flowers earlier the following year
• Needs a cold frame or greenhouse

Best for: early flowers and robust plants.

Late Winter to Early Spring (January–March)

• The most popular and reliable time
• Suitable for most UK gardeners
• Sow indoors, in a greenhouse, or cold frame

Best for: beginners and consistent results.

Spring (April–May)

• Sow seeds directly outdoors
• Only once the risk of frost has passed
• Flowers a little later but still grow well

Best for: gardeners without indoor growing space.

🌿 When to Plant Sweet Pea Plants Outside

If you’re planting out young sweet pea plants:

• April–May in most of the UK
• Wait until all risk of frost has passed
• Harden off plants over 7–10 days before planting

Planting out too early is the most common mistake.

🌸 Quick Answer

👉 Plant sweet pea seeds in autumn or late winter, and plant them outside in spring once frost risk has passed.

Choose the timing that suits your space and climate, and you’ll enjoy months of colourful, fragrant flowers.