How to care for sweetpeas - fill your summer garden with these stunning annuals

Knowing how to care for sweet peas is essential if you want to make the most of these stunning annuals. They only flower once, and their very specific growing requirements could see your sweet pea-growing efforts fall short. 

The perfect climbing plants, sweet peas are ideal for adding extra height, colour, and texture to your garden. But while sweet peas may be sweet, they’re not the easiest plants to care for. From sowing to watering, deadheading and supporting, sweet peas require some TLC to bloom throughout the whole summer. 

That’s why we’ve consulted with the experts to create the ultimate sweet pea care guide to make growing sweet peas easier than ever. Follow these sweet pea care guidelines, and you’ll be rewarded with the garden idea you’ve been dreaming of. 

How to care for sweetpeas 

Whether you’re looking to fulfil your dreams of a cottage garden or you’re just looking to experiment with new flowers to fill your outdoor space, sweet peas are a great option. And while they’re certainly a good choice for novice gardeners, it’s also important to understand how to care for sweet peas to get the most out of them. 

What you’ll need

• Sweetpea seeds - like this Old Fashioned Mixed Sweet Pea Seed from B&Q
• Seed trays - like this MIXC Seed Trays,10 Pack from Amazon
• Seed compost - like this Westland John Innes Peat Free Seed Sowing Compost from Homebase
• High-potash fertiliser - like this Levington Tomorite Liquid Tomato Food from Amazon
• Trowel - like this Spear & Jackson Traditional Handtool Set from Argos
• Plant supports - like this True Products Climbing Plant Support from B&Q
• Watering can - like this Spear & Jackson Steel Watering Can from John Lewis

1. Sowing

Although you can buy fully-grown sweet peas from the garden centre, there’s nothing better than sowing your own sweet peas. We have more detailed guides on how to grow sweet peas from seed and when to sow sweet peas, but the general guidelines are fairly simple to follow. 

Oliver Hill, gardening expert and founder of Garden List, explains, ‘Sweet peas are cool-season flowers, so the best time to sow them is either in late autumn or early spring. In the UK, sowing in March or April is ideal, but for earlier blooms, you can start them in autumn and overwinter them in a cold frame or greenhouse.’

Timing isn’t the only thing you need to consider when sowing your sweet peas, though. Oliver adds, ‘Sweet pea seeds have a hard outer coating, so it's beneficial to soak them in water for 24 hours before planting. This softens the seed coat and speeds up germination.’

‘Then, sow the seeds about 1-2 cm deep in pots or trays filled with good quality seed compost. Keep the soil moist but not waterlogged. You can also sow them directly into the ground where they are to grow, but ensure the soil is well-drained and fertile.’

2. Planting

Whether you’re growing sweet peas from seed or buying established plants, knowing how to plant your sweet peas successfully is key to beautiful blooms year after year. 

Thankfully, you’re in luck if you have a south-facing garden, as sweet peas love to be planted in a sunny spot - as long as there’s well-draining soil. 

Steve Chilton, garden expert at LeisureBench says, ‘Sweet peas like to be planted in a location that receives full sun to partial shade. They best thrive in areas that receive at least 6 hours of direct sunlight per day. In terms of soil, they prefer well-draining soil that is rich in organic matter.’

Oliver also suggests, ‘Space them about 10-20 cm apart.’ this will allow for sufficient growth. 

Steve Chilton

Steve is a passionate and knowledgeable garden expert with several years of experience within the field and has developed strong expertise for all things nature and plants. Steve is a keen educator and loves to share this knowledge with others. He strives to simplify complex garden practices and encourage eco-friendly gardening.

3. Watering

As they love the sun and well-draining soil, it probably won’t surprise you to learn that sweet peas also love to be well-watered. It’s good practice to keep the soil moist at all times, which during high temperatures could mean watering them a few times a week. 

It’s essential that they have access to constant moisture, as this can affect their growth and their self-seeding nature. 

4. Support

Sweet peas may be climbers, but they’re also very delicate. This means that they’re always going to need some extra support. 

How you support your sweet pea plants is up to you, but offering them the likes of trellis, netting, or pea sticks to cling to as they grow is the best way to ensure tall blooms that make a real statement in your garden. 

5. Fertilising

As well as needing structural support, your garden full of sweet peas will thank you for giving your plants extra fertiliser every now and then. 

Oliver says, ‘Sweet peas benefit from regular feeding with a high-potash fertiliser once they start to flower.’

This is handy for those growing tomatoes in pots, as Steve explains. ‘You can use fertiliser when you notice the flowering start, but just make sure that it’s a potash fertiliser. A tomato feed would be fine for this.’ 

If you can, do this every few weeks while your sweet peas are in flower, and you may even find that this increases their blooming time. 

6. Deadheading

Many of the plants in your garden require deadheading, and sweet peas are no different. And while it’s important to deadhead any spent flowers, most experts would also suggest picking healthy flowers while they’re still in full bloom, too.

Oliver says, ‘Regularly picking the flowers encourages more blooms. If you leave the flowers to turn into seed pods, the plant will stop producing new flowers.’ 

Thankfully, sweet peas make a great addition to big bouquets or smaller vases, so you can still make use of these flowers when you’ve picked them. 

7. Pruning

Alongside regular deadheading, it’s also important to prune your sweet peas when they have finished flowering. This should be sometime in the autumn.

To do this, you should cut your sweet peas down to ground level, being sure to leave the roots in the ground as you do so. 

FAQs

What is the secret to growing sweet peas?

If you want to be rewarded with the best sweet peas you can grow, it’s important to plant them in a sunny position in your garden and keep them in rich, well-draining soil. Not only that, but you should also keep them well-watered. 

Sweet peas are traditionally grown as climbers, so supporting them with trellis or bamboo sticks is key to making the most out of them. Then, make sure you regularly pick the flowers to encourage improved growth.

What is the best month to plant sweet peas?

If you’re growing sweet peas from seed, you can sow in either October or November or in early Spring. 

If you’re planting established sweet pea plants, you can do this anytime between April and June. 

What do sweet peas need to climb?

Sweet peas need support if you want them to successfully grow as climbers. There are many different ways to offer your sweet peas support, but the easiest option is to grow them up trellis or netting. 

Alternatively, you could stake them when you plant them. 

Take care of your sweet peas, and they’ll certainly take care of your garden.