Sweet peas have been a favourite flower in our gardens for generations thanks to their sweet scent and wide range of flower colours – from whites and pinks to blues, reds, lilacs and purples. As well as brightening up the garden they make good cut flowers for decoration indoors. Annual sweet peas flower, set seed and die all in one season and perennial varieties can be encouraged to remain productive for several seasons. Sweet peas produce flowers over a long period which makes their short lives all the more brilliant. Dwarf varieties grow to no more than a hand’s length tall whereas climbing varieties reach up to 10 feet in height. Bees and butterflies are attracted to their flowers.
Companions Sweet peas attract bees and butterflies into the garden. Like other pea family members, they fix nitrogen into the soil and so they benefit a wide range of vegetables such as brassicas, leafy greens like silverbeet and spinach and salads.
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Sow or plant in early spring countrywide. In warmer areas sweet peas can be sown outdoors in autumn and early winter if a sunny, well-drained spot can be provided. This helps them to get off to a good start in spring.
Sweet peas grow well in full sun and partial shade. Choose a site where you can also offer them some protection from strong winds.
Sweet peas like fertile, well-drained soil that has plenty of compost or manure dug through it. If your soil is sticky then dig in coarse sand or fine pumice to help improve drainage.
Seeds germinate better if they are soaked over night before sowing.
Sow outdoors: Sweet peas don’t like their roots to be disturbed and so its better if you can sow them directly into your garden beds or large containers – this saves damaging seedlings when you transplant them from punnets or seed trays.
Sow seeds a finger-tip deep and about a hand’s length apart in soil that has been well dug through and enriched with plenty of compost or well-rotted manure and water well. When seedlings get to about a hands’ length in height pinch out the growing tip to stimulate bushy growth. This helps to produce stronger plants that should flower well.
Sow indoors: It is okay to sow sweet peas into punnets and trays as long as you are careful with their long tap roots come planting time. If you are going to grow them through winter and plant outdoors in spring then sow into pots and grow on in a cool greenhouse or cold frame.
Sow seeds a finger-tip deep in punnets or trays filled with seed raising compost and water well. One or two seeds per individual planting cell is enough – you can pinch out the weaker one when they have sprouted and have a couple of pairs of leaves. When sowing in trays, space seeds about a finger’s length apart. Place in a cold frame, on a cool windowsill or in a cool greenhouse. When seedlings are about a finger length tall, transplant them into larger pots – something about a full hand’s length deep would be good.
Plant seedlings carefully. Dig a hole that is just deeper than the plant pot your seedlings have been growing in. Ease seedlings form pots, causing as little disturbance to the roots as possible and lay them along the palm of your hand. Lower them into the hole. Whilst gently holding the seedlings and allowing the soil and roots to hang into the hole, backfill around it them. Gently pat down soil around the surface. Sweet peas should be planted about two hands’ lengths apart – you don’t want to plant them too close or they can become susceptible to powdery mildew due to poor ventilation.
Water young seedlings in dry periods. Once they are established and starting to grow, pinch the growing tips out again to encourage bushy growth. Feed plants fortnightly with liquid worm juice or liquid manure to keep plants productive and ensure they get regular water right through summer when it is dry. Mulching with rotted manure helps with both these feeding and watering tasks.
Unless they are self-supporting dwarf varieties, sweet peas need to clamber over or grow through something. A shrub makes a good climbing frame and so does trellis or a large climbing plant like a rose but more often, bamboo canes with twiggy material or mesh tied to them or purpose built planting obelisks and pyramids are used.
Flowers can be cut for use indoors. To keep plants going, pick regularly.
Annual varieties of sweet pea will die at the onset of winter. Allowing them to set seed means you can collect seed for future sowings. Perennial varieties will die right back to ground level in winter and then re-shoot come spring.