How to grow annual climbers from seed

Do it:

Mar, Apr, May

Takes just:

30 minutes

There are a range of easy-to-grow, climbing annuals that will flower non-stop from June until the frosts, producing striking blooms and sculptural leaves. Because they grow 1.8m to 3m or more in a season, half the joy is amassing so much plant from one small, inexpensive seed.

Sweet peas aside, annual climbers are rarely seen in borders, but they're easy to grow from seed with a heated propagator in a greenhouse (or a frost-free porch or indoor window sill). Species to try include Spanish flag (Ipomoea lobata), Canary creeper (Tropaeolum peregrinum) and black-eyed Susan (Thunbergia alata).

Annual climbers are often grown as fast cover-ups for sunny fences and trellises, but they make excellent pot plants for large containers.

You will need

  • Annual climber seed
  • Glass bowls for soaking seed
  • Seed labels
  • 10cm pots
  • Larger pots for potting on
  • Seed-sowing compost
  • Heated propagator
  • Twigs for support

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To encourage germination, soak the seeds overnight in cold water to soften their coating. Keep the different varieties separate and clearly labelled.

Use 10cm pots and fill with a seed-sowing compost. Scatter the seeds on the surface, then cover with another thin layer of compost.

Keep pots covered in a propagator at approximately 21-24°C (average room temperature). Water regularly to prevent the compost drying out but don't let the pots become waterlogged.

Seedlings should appear within two to three weeks. Once the first true leaves appear, transfer each seedling to its own pot, holding it by the leaf not the stem. Keep watered and in a frost-free place.

Once climbers start to grow, give the pots some more room and push twiggy supports into the compost to prevent plants tangling with each other. From April, gradually harden off plants in readiness for moving outdoors.

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If you don't want to sow seeds in February, you could wait until the weather warms up in April and sow pots in a coldframe for slightly later-flowering plants

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