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Updated: 26 May 2022

How to grow sweet peas and best varieties

Sweet peas are annual climbers with unbeatable fragrance. Discover our best sweet pea varieties and tips for how to grow them.
Ceri Thomas
Sweet peas

The frilly, perfumed blooms of sweet peas, held on long, straight stems, make perfect cut flowers. Plus, the more you pick them, the more buds form to make fresh flowers. They’re easy to grow as well. Most are climbers, which can be trained up teepees of canes, but you can also buy dwarf varieties for pots and baskets.

Which? Gardening magazine grew a range of popular varieties to see which would give us the best display.


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Key facts

Plant type Hardy annual climber 

Position In a sunny border climbing up a fence or obelisk 

Soil Any

How to grow sweet peas: month by month

JanuaryFebruaryMarchAprilMayJune


SOWPLANT
FLOWERING
JulyAugustSeptemberOctoberNovemberDecember
FLOWERINGFLOWERING
SOW

Best sweet pea varieties

Which members can log in now to see the full results and which are our Best Buy varieties. If you're not a member, join Which? to get instant access.

Full testing results for sweet peas

Sweet peas for scent

Variety name Overall ratingFlowering duration Flower impact Display Scent Pests & diseases 
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USING THE TABLE OVERALL RATING The more stars the better. Rating ignores price and is based on flowering duration 30%; flower impact 20%; scent 30%; display 10%; pests and diseases 10%

Grandiflora sweet peas

Variety name Overall ratingGermination Flowering duration Scent Flower coverage Pests & diseases Flowering impact Garden worthiness 

USING THE TABLE The more stars the better. OVERALL RATING Ignores price and is based on: germination 5%, flowering period 25%, scent 20%, flower coverage 10%, pest and diseases [resistance] 10%, impact [includes ratings both for display in the garden and as a cut flower] 20%, garden worthiness 10%. Garden worthiness is a subjective rating based on how this variety compares to others.

Sweet peas for pots

Variety name Overall ratingGermination Flowering duration Impact of display Weather resistance Pest & diseases Fragrance 

USING THE TABLE: OVERALL RATING The more stars the better. Score ignores price and is based on: flowering duration 45%; impact of display 25%; fragrance 10%; pest and disease resistance 10%; weather tolerance 5%; germination 5%.

How we test sweet peas

Which? Gardening magazine trialled a number of the different sweet pea varieties at our trial ground in North London. We sowed them in October and grew them in our coldframes through the winter until April, when we planted them outdoors. The varieties for pots were planted in pots and hanging baskets. The ordinary varieties were tied in and deadheaded weekly, and sprayed with insecticide to control aphids and prevent viruses spreading. Throughout summer we noted how strong the scent was, how much flower coverage the plants had and if any were affected by pests or diseases. We also assessed them for the length and thickness of their stems to see if any would be good for cut flowers.

Types of sweet peas

They’re divided into two groups: grandiflora and Spencer types. For an expert, the distinction is in the ‘keel’ petals (the lowest two petals) – grandiflora types have a ‘clamped’ keel, while Spencer types don’t. For the rest of us the difference is that Spencer types have big, frilly blooms and, despite their name, grandifloras have smaller flowers and stronger scents. 

Modern breeding has blurred these divisions. Nowadays, grandifloras are claimed to have both the big flowers and long stems we look for in cut flowers, as well as the profuse flowering and strong scent we love in the garden.

Sowing

Sow seeds during October in rootrainers or deep pots using a Best Buy compost for sowing seeds. There's no need to pre-treat seeds. Keep them at 16-18°C and they should germinate in 7-14 days.

Mice eat sweet-pea seeds, so cover the seed trays or pots with a propagator lid until they’ve germinated.

Caring for your plants

Overwintering

Once germinated, move them to a cool, sheltered position such as a coldframe. Young sweet peas like growing in cool conditions, but don’t tolerate being frosted. If it’s too warm they can become weak.

Planting

Plant them in March or early April against a support they can wrap their tendrils around, such as a teepee made of bamboo canes, then tie them in initially as they grow.

Picking the flowers

Pick sweet peas regularly to encourage them to keep blooming. At the end of the season, leave some flowers to set seed so you can collect it for sowing in autumn.

Common growing problems

Flower buds falling off

Wet soils, warm days and cold nights can make plants drop their buds. It’s nothing to worry about and they’ll soon recover as the nights warm up.

Virus

Sweet-pea viruses cause streaked flowers or mottled leaves. They are easily spread by aphids, so be sure to control them. Remove infected plants and clean secateurs between working on plants.

Read more about virus on sweet peas

Powdery mildew

In dry summers, powdery mildew can become a problem. Keep plants well watered but don’t wet the leaves. Spraying with a suitable fungicide can slow its spread.

Read more about powdery mildew a