Grow Perfect Sweet Peas

Sweet peas (Lathyrus odoratus) are the prettiest and most rewarding spring-blooming cut flowers to grow. They should be sown in April in the Southern Hemisphere. Sweet peas need a bit of elbow grease in the form of proper soil preparation before sowing. They also need a support structure to keep them in the air.

The sweet pea trench

Sweet peas need a dug-out trench filled with enriched and well-draining soil to germinate and grow well in. This is unlike the direct sowing of other late-winter and spring annuals into a tilled seedbed,

Pick a sunny spot for the plants to grow. A day before you plant, water the area to make the digging easier. Dig out and prepare a trench at least 50cm deep in which you are going to plant your seeds. Mix the excavated soil with ample quantities of compost, old kraal manure and bonemeal before backfilling the trench.

A place for sweet peas to climb on

Climbing varieties of sweet peas need a structure to grow up. A wire fence can act as a support and is less work than erecting a structure. Alternatively you can grow them on bamboo or steel tee-pees that you can buy at garden centres. Or, simply fashion a home-made structure with poles and wire or strong string.

Don’t be shy of picking the flowers regularly, as this will encourage the plants to produce more.

Creating a sweet pea trench in the veggie garden is good as the flowers attract pollinators like bees.

Preparing and planting sweet pea seeds

It is advisable to soak the seeds in hot water overnight before planting them about 5cm deep and 10cm apart. Keep the soil moist until the seeds have germinated, and then water regularly if the top layer of soil feels dry. A mulch of compost around the plants is recommended to shade the roots and to keep the soil moist for longer. Another option to create cool shaded roots is to plant seedlings of dwarf sweet pea varieties, which do not need staking, around the climbers to give you a double-decker effect.

Seedlings of dwarf sweet peas are often available in seedling trays at garden centres. Feed the little seedlings once or twice with a growth stimulant like Kelpak to make them strong and healthy. When the seedlings have reached a height of about 15cm, you can start pinching out their growth tips to encourage bushy plants with lots of flower-producing side branches. As they grow skywards, keep gently helping them to wind through and cling to their support structure.