Growing sweet pea plants is a popular choice for UK gardens thanks to their scent, colour and climbing habit. With the right sowing method and seasonal care, they grow well in borders, containers and compact outdoor spaces. Planning from seed to planting helps produce stronger plants.
This guide explains sowing sweet peas, the use of propagators, ongoing care, feeding and growing sweet peas in pots. Each section focuses on conditions commonly found in UK gardens and aims to help you get steady flowering through the season.
Sowing Sweet Peas for Reliable Germination
Sowing sweet peas in pots allows better control over moisture and temperature. For best results, sow seeds in long pots filled with a good seed sowing compost during March or April.
Propagators can help keep conditions stable during germination, especially when sowing in late winter or early spring. A windowsill propagator or gently heated unit supports even sprouting without cold nights slowing progress.
Recommended: propagators and root trainers
Propagators and root trainers for sowing sweet peas with steadier germination and stronger early root growth.
Sow seeds individually in 9cm pots or place five to seven seeds in a 12.5cm pot. Once seedlings reach around 5cm high, pot them on individually and place in a light but cool location. Too much heat and not enough light will cause the seedlings to become leggy. Direct sowing outdoors can work, though results are often less consistent.
When to Plant Sweet Peas Outdoors in the UK
When to plant sweet peas depends on sowing time and local temperatures. Autumn-sown plants can go out in mid-spring, while spring-sown plants are usually ready from late spring to early summer after hardening off.
Space plants 20–30cm apart in full sun. Water thoroughly after planting and continue during dry spells. A fertile soil that holds moisture while draining freely supports steady development.
How to Care When Growing Sweet Peas
When plants are about 7.5–10cm high, pinch out the growing tips to encourage side shoots and fuller growth. This helps produce more flowering stems and a sturdier plant shape.
Feed choice matters once plants are established. Before flowering, use a general-purpose liquid feed to support steady growth. When buds form, switch to a high potash liquid feed, such as tomato feed, to support flower production.
Recommended: sweet pea plant food
Sweet pea plant food and pot watering supplies to support steady flowering when growing sweet peas in pots.
Apply liquid feed every 7–10 days during flowering, especially for container plants. Water the compost or soil before feeding and avoid feeds high in nitrogen, as these can reduce flowering.
Cut flowers often before they fade to reduce seed pod formation and encourage further flowering. Dry conditions and temperature stress can cause bud drop, so aim for consistent watering through summer.
Growing Sweet Peas in Pots for Patios and Balconies
Growing sweet peas in pots suits patios, balconies and smaller gardens. Choose deep containers that allow good root growth and use strong supports such as canes or compact trellis.
Dwarf types suit pots, hanging baskets and low planting areas. Keep compost evenly moist and place containers in full sun. Feed regularly once buds form, as nutrients are used up more quickly in a pot.
Supports and Training for Growing Sweet Peas
Sweet peas climb using tendrils and need support early in their growth. Pea sticks, bamboo wigwams, trellis or netting all work well. Plants can scramble naturally or be tied in as they climb.
Recommended: sweet pea support
Sweet pea support for vertical growth using obelisks and climbing structures in borders and containers.
Cordon growing is used by growers who want large blooms. Plants are trained as single stems on canes, with side shoots and tendrils removed so energy goes into flowering.
Common Problems When Growing Sweet Pea Plants
Powdery mildew appears as a white coating on leaves and is more common in dry conditions. Improve air flow, water consistently, and remove affected growth to limit spread.
Slug and snail pressure is common on young seedlings. Check plants at night, remove pests by hand, and try a barrier such as grit around the base. Aphids can also cluster on new shoots, so wipe off small groups and encourage predators like ladybird and hoverfly.
Benefits of This Sweet Pea Growing Approach
- More even germination by using pots, root trainers and propagators when conditions are cool
- Stronger root growth from deeper containers and careful watering during early stages
- More flowering stems by pinching out tips at the right plant height
- Better bloom production by switching to a high potash feed once buds appear
- Improved results in containers with deeper pots, steady moisture and regular feeding
Frequently Asked Questions on Growing Sweet Peas
How tall do sweet peas grow?
Most climbing types reach around 1.8–2.4 metres with suitable support.
Can you grow sweet peas in pots?
Yes, growing sweet peas in pots works well with deep containers, full sun, steady moisture and feeding once buds form.
How to grow sweet peas up a post?
Set a post or canes in place early, then tie young stems loosely and guide growth upwards as new shoots appear.