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Sowing sweet peas

What to plant in March

Find out which flowers and veg crops you can sow in March.

Plenty of flowers and vegetable crops can be sown in March in the UK, when the days are beginning to lengthen and become warmer. March is a good time to sow a huge variety of seeds, some of which can be sown direct and others sown indoors to be planted out after all risk of frost has passed.

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Some crops, such as chillies and tomatoes, should be sown early in the year to give them the long growing season they need. Others, such as fast-growing beetroot and salads, can be started off early so you can enjoy them in late spring and early summer, but keep sowing them every few weeks to extend the harvest.

Hardy annuals can be sown direct outside, where they are to flower. These do best on ‘poor’ soil, so don’t enrich it with fertiliser. Half-hardy annuals such as dahlias and cleome, and perennials are best sown under glass, and should be planted out into fertile soil after all risk of frost has passed.

Find out which flowers and vegetable crops you can sow in March, below.

You will need:

It’s exciting to be able to start sowing a variety of different seeds at this time of year, and to give them the best chance you might find that it’s worth investing in additional kit, which we’ve suggested below.

Vegetables to grow in March

Broad beans

Harvesting broad beans

Broad beans are a productive, easy-to-grow crop, producing tender beans in large pods. Sow direct, spacing the seeds 30cm apart. Can be grown in pots and the young shoot tips can be used in salads. Find out how to grow broad beans in our helpful guide.

Chard

Chard leaves

Swiss chard makes a very attractive container plant. Pick regularly for baby leaves or allow to grow for larger leaves that can be steamed like spinach. Sow in pots or direct in the ground, covering with 2cm of compost. Inspired to grow-your-own chard? Read how to grow chard.

Chillies

Chillies do best in pots and can be grown on a sunny windowsill or in a greenhouse. Choose compact, small-fruited varieties and early ripeners for a more reliable harvest in cooler weather. Sow on to the surface of multi-purpose compost and cover with a thin layer of compost or vermiculite. Cover the pots with a propagator lid or clear plastic bag held in place with an elastic band to create a mini greenhouse. Place on a sunny windowsill or on a heated propagator. Remove the plastic bag as soon as seedlings appear. For more tips and advice, check out our guide on how to grow chillies.

Chives

Chives are great for container growing as they don’t take up much space. Pick regularly to encourage new leaves to grow. If left to bloom, chive flowers attract pollinators. Sow a pinch of seeds into individual seed modules filled with peat-free, multi-purpose compost. Cover with 1cm of compost, water well, label and place on a sunny windowsill or in a greenhouse. Plant outside or into larger pots after all risk of frost has passed. For more information, read our guide on how to grow chives.

Kale

Kale is perfect for a semi-shaded spot. Grow in pots or the ground for cut-and-come again crops of young leaves to use in salads, or lightly steamed as a veg. Sow three seeds into individual seed modules filled with peat-free multi-purpose compost. Cover with 2cm of compost, water well, label and place on a sunny windowsill or in a greenhouse. Haven’t grown Kale before? Check out our comprehensive guide, how to grow kale.

Peas

Sow peas in large pots for shoots or in the ground for peas. Choose hardy, early varieties for sowing in March. Sow seeds in single or double lines, 5cm deep and 30cm apart. Looking for more information? Read how to grow peas

Potatoes

Potatoes can be grown in the ground or in pots. Chit the seed potatoes by placing the tubers in old egg boxes or seed trays on a cool, light window sill to encourage shoots to form. Towards the end of the month, plant the sprouting tubers in to pre-dug trenches or in pots or sacks on top of 10cm of compost, then cover with an additional 10cm of compost. Earth up or add more compost when the shoots appear, and if you need more tips and advice, read our guide: how to grow potatoes.

Sweet peppers

Tender sweet peppers need warmth and sunlight. They do best in pots, ideally in a greenhouse. Sow seeds onto the surface of moist, peat-free, multi-purpose compost, and then cover with a light layer of compost or vermiculite. Cover with a propagator lid or clear plastic bag held in place with an elastic band to create a mini greenhouse. Place on a sunny windowsill or heated propagator. Remove the plastic bag as soon as seedlings appear. We’ve also put together a comprehensive guide on how to grow sweet peppers.

Tomatoes

Harvesting ripe tomatoes

Tomatoes can be easy to grow, but cordon varieties need support and regular pruning. Choose bush, tumbling or cordon cherry varieties for pots, and cordon varieties for growing in the ground or in growing bags. Sow seed on to the surface of moist, peat-free multi-purpose compost, and cover with a fine layer of compost or vermiculite. Cover with a propagator lid or clear plastic bag held in place with an elastic band to create a mini greenhouse. Place on a sunny windowsill or heated propagator. Remove the cover as soon as seedlings appear. Find further inspiration about how to grow tomatoes in our comprehensive guide.

Beetroot

Beetroot will germinate in low temperatures, so can be sown in March. Sow seed direct in shallow drills and cover with a fine layer of soil or compost. Harvest when the beets have reached golf ball size. Find out more in our guide, how to grow beetroot

Salad

Start sowing salads from March onwards, and you’ll be enjoying delicious leaves for months to come. In March, they are best sown indoors and planted out after all risk of frost has passed. Read more about how to grow salad leaves in our guide.


Flowers to grow in March

Hardy annuals

Ladybird poppy flowers

Hardy annuals can be sown directly where they are to flower. Prepare the ground well by clearing it of weeds and raking it to a fine tilth, and don’t be tempted to enrich the soil. For more tips and advice, read our comprehensive guide, how to sow hardy annuals. Try Ammi majus, borage, clarkia, cornflowers, and Papaver commutatum ‘Ladybird’ (pictured).


Sweet peas

Sweet peas can be sown under cover from October to March. They like a long root run, so sow into deep pots or modules. Sweet peas need some form of support as they grow – a wigwam is ideal. For more information about how to grow sweet peas, read our guide. Plan ahead, and buy supports from Crocus and Amazon


Wildflower mixes

Annual wildflower mixes can be sown in March. As with hardy annuals, prepare the soil well by removing weeds and raking to a fine tilth, but do not enrich the soil. Need some inspiration about which varieties to choose? Check out our guide to 20 British native wildflowers to grow


Half hardy annuals

Half hardy annuals like cleome (pictured), antirrhinum, zinnia and cosmos can also be sown in March. They are not frost hardy, so must be sown under cover. Sow seeds on the surface of a tray of peat-free, multi-purpose compost, then cover with vermiculite, water and place the tray in a heated propagator. Pot on after the first true leaves have grown and plant out after all risk of frost has passed.

Dahlias

Dahlias are tender perennials that will flower in their first year if sown in the greenhouse in March. Fill a pot or seed tray with moist compost and lightly firm the surface. Gently push your dahlia seeds into the compost. Cover pots with an inflated clear polythene bag, held in place with a rubber band. If sown in seed trays, cover with a propagator lid. To find out more tips and advice, read our guide: how to grow dahlias.


Fast-growing perennials

Early spring is the ideal time to sow quick-growing perennials under glass. Try sowing echinacea, coreopsis, lupin or achillea and you may be rewarded with flowers this year. Sow indoors, scattering seed on the surface of moist compost. Cover with a propagator lid or polythene bag and keep on a window sill or heated propagator. Remove the cover when seedlings have appeared.

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