Sweet peas are the epitome of charm, offering delicate, fluttery blooms and a fragrance that’s straight out of an English cottage garden. These climbing annuals are perfect for trellises, fences, and containers, bringing both beauty and scent to any space. With a bit of care, sweet peas will reward you with a cascade of colourful blossoms throughout the summer.
Here’s all you need to know about growing sweet peas.
Types of sweet peas
Sweet peas come in various forms, each with unique traits:
- Grandiflora
- Known for their strong fragrance and delicate flowers, ideal for cutting gardens.
- Spencer Types
- Large, ruffled blooms on long stems, perfect for show gardens.
- Dwarf Varieties
- Compact plants like ‘Cupid Mix,’ ideal for containers and small spaces.
How to sow sweet peas
Sweet peas can be sown in spring either in pots or directly in the ground, or in autumn, in a cold frame or greenhouse.
You can find a wide range of sweet pea seeds in our flower seeds collection.
Although sweet peas generally germinate well, soaking them in water around 24 hours before sowing can improve germination rates.
Sowing cosmos indoors:
- Fill seed trays or small pots with a light, well-draining seed compost.
- Sow seeds on the surface and lightly cover them with a thin layer of compost.
- Keep the soil moist and place in a warm, bright location. Germination occurs in 7-10 days.
- Once seedlings develop two sets of true leaves, transplant them into larger pots.
- You should pinch out the growing tips of sweet pea plants when they are 4–6 in (10–15 cm) tall. This is done by squeezing the growing tip between your thumb and forefinger, just above a leaf joint, leaving only 2–3 leaf nodes.
- Plant out your sweet peas from late May, once all risk of frost has passed.
Top tip: Try sowing sweet pea seeds in toilet roll tubes as you can then plant them out directly and the cardboard will naturally break down.
Where to plant sweet peas outdoors
Sweet peas can be planted in many different ways. As climbing plants, they’ll need some kind of support to produce the best blooms and height.
- Choose a sunny, well-drained site with shelter from strong winds.
- Sow seeds directly into the soil, spacing them 30cm apart for smaller varieties and 45cm for taller ones.
- Lightly cover with soil and water gently.
Here are some ideas for creating gorgeous sweet pea displays:
Build a sweet pea tipi
Image credit: https://pin.it/1VGns1pHp
A sweet pea tipi is a beautiful and functional way to grow these climbing flowers, creating a striking vertical display. It’s perfect for small gardens or as a focal point in a larger space.
- Arrange six to eight bamboo canes or long garden stakes in a circular shape, about 60cm in diameter.
- Tie the tops of the canes together securely with twine, forming a tipi shape.
- Plant 2-3 sweet pea seedlings or seeds at the base of each cane.
- Gently tie the young vines to the canes as they grow to guide their upward climb.
Plant sweet peas by a Trellis
Image credit: https://pin.it/3h4DMtV8w
A trellis provides a flat, decorative surface for sweet peas to climb, making it an excellent choice for garden borders or alongside walls.
- Place a sturdy trellis in a sunny spot with well-draining soil.
- Sow seeds or plant seedlings 15cm apart along the base of the trellis.
- Gently tie the stems to the trellis when they are about 10cm tall to encourage proper growth.
- Regularly guide new growth to the trellis to keep the plants neat and ensure even coverage.
Create a sweet pea arch
Image credit: https://pin.it/6bxjA42q3
A sweet pea arch transforms your garden into a whimsical haven. As the plants climb, they form a canopy of fragrant blooms perfect for framing pathways, garden entrances or seating areas.
- Install an arch frame in a sunny location with fertile soil.
- Plant sweet pea seeds or seedlings at the base of each side of the arch, spacing them about 15cm apart.
- Tie the stems to the arch as they grow, encouraging them to climb upwards and meet in the middle.
- Pinch out the growing tips once they’ve reached the top to promote side shoots and additional blooms.
Caring for sweet peas
Watering: Water regularly to keep the soil evenly moist but not waterlogged. Mulching around the base can help retain moisture.
Feeding: Feed plants every two weeks with a high-potash fertiliser (e.g., tomato feed) to encourage flowering.
Pinching Out: Pinch out the growing tips of seedlings when they are 10-15cm tall to encourage bushier growth.
Staking and Tying: Regularly tie the vines to their supports to keep them upright and prevent tangling.
Deadheading: Remove spent flowers promptly to prolong the blooming period and prevent the plants from setting seed.
Sweet peas are a great addition to any outdoor space. Full of colour, fragrance and aesthetically pleasing, these blooms will brighten up your garden every year.
Sweet pea FAQ
Do sweet peas need full sun?
Yes, sweet peas thrive in full sun and require at least 6 hours of direct sunlight daily.
Why are my sweet peas not flowering?
Sweet peas may fail to flower if they receive too much nitrogen or insufficient sunlight. Ensure they have plenty of light and use a fertiliser high in potassium.
Can I grow sweet peas in containers?
Yes, dwarf varieties are ideal for containers, while larger types require deep pots with sturdy supports.
Do sweet peas come back every year?
Most sweet peas are annuals and need to be sown each year. However, perennial varieties, like Lathyrus latifolius, return annually but lack fragrance.
How tall do sweet peas grow?
Depending on the variety, sweet peas can grow anywhere from 30cm (dwarf types) to over 2m (climbing types).
Are sweet peas edible?
No, sweet peas are toxic if ingested. They are ornamental flowers and not to be confused with edible peas.
Why are my sweet peas leggy?
Sweet peas need lots of light, and if they don't get it, they can become leggy which means the stems grow very long, in search of light or one-sided light. You can try moving them to a brighter spot, or turning the pots regularly to prevent them from leaning.