Sow more sweet pea seeds and care for seedlings, says Gardening Editor Ruth Hayes

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Sow sweet peas now for flowers this summer

I sowed my first batch of sweet peas back in the autumn and now, at the tail-end of winter, I am starting a second batch.

Although sweet peas are hardy, I don’t want to sow them in the beds where they will grow as the cold and damp may cause them to rot, and hungry rodents will see them as a tasty snack.

So I am starting them off undercover and will plant out the sturdy young seedlings in late spring once they have been hardened off and acclimatised to the elements.

Sweet peas are easy to sow and grow, and are an ideal “starter” seed for novice gardeners. The seeds are also popular with hungry mice, but you can deter rodents by soaking the seeds in liquid paraffin overnight before sowing – it makes them taste revolting!

Sweet peas have long tap roots, and need a deep pot of compost to grow robustly and well. I either sow several seeds around the sides of a deep 10in (25cm) pot, or use root trainers.

These are like deep and narrow modules that you open up when you come to plant out the seedlings. This allows you to place the rootball in the soil with a protective layer of compost around it.

The sweet pea seeds I sowed in autumn are now healthy young plants sitting out the winter in our cold frame.

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Pinch out the tips for robust sweet pea plants

I have pinched them out to encourage bushy growth and check them regularly for signs of pest attack and disease.

Seedlings grow pale and spindly if they have too much warmth and insufficient light. If this happens, move them somewhere cooler and brighter, where they will recover.


Top tips for sweet peas

  • Keep slugs and snails away from sweet pea seedlings that are growing in a cold frame by standing their pots on a bed of gravel.
  • Encourage good airflow around young plants to prevent mould and mildew.


How to sow sweet peas successfully

Sowing_sweet_peas scarify for web

  1. The hard shells of sweet pea seeds can slow germination, so weaken the shells with a nail file or, if you have a steady hand, chip them slightly with a sharp, clean garden knife.
    sowing sweet peas root trainer for web
  2. Like all legumes, sweet peas have substantial root systems and need deep compost. Large, deep pots or root trainers are ideal for germination.


Caring for autumn-sown sweet pea seedlings

  • Sweet pea seedlings sown last autumn should be growing into robust young plants.
  • They won’t put on much top growth in winter, but their roots will develop and strengthen.
  • Prevent them from becoming spindly and encourage strong, bushy growth (with more flower stems) by regularly pinching out the growing tips.
  • Make sure the plants are kept well ventilated, as they can fall prey to mould and mildew. If they are in a cold frame, raise the lid on warm days, closing it at night.
  • Don’t let the compost dry out and protect the seedlings from pests, as slugs, snails and rodents are partial to pea shoots.