What to sow and grow in March

Sunflower SunBelievable™ Duo from Thompson & Morgan

Celebrate the arrival of spring by sowing bright sunflower seeds.
Image: Sunflower SunBelievable™ Duo from Thompson & Morgan

It's March, and spring is finally here. In milder parts of the UK the soil is starting to warm up for outdoor planting, but if you're still getting frost, there are plenty of seeds that can be started in a propagator.

Here's a list of the flowers, vegetables and fruit you can sow and grow in March, and for more information about other gardening jobs to start in March, read our helpful companion guide today:

Flowers to sow and grow

Poppy 'Amazing Grey' from Thompson & Morgan

Sow poppies in March for mid-summer flower displays.
Image: Poppy 'Amazing Grey' from Thompson & Morgan

In the greenhouse/indoors

  • Sow half-hardy annual seeds inside now, ready for planting out in June. Start ageratum, aster, brachycome, cosmos, celosia, petunia and salvia in a heated propagator or on a warm windowsill for summer and autumn border colour. Sow dahlia seeds indoors to plant out in summer and provide tubers for lifting in the autumn.
  • Pot on rooted cuttings of tender perennial plants and hardwood cuttings taken last year.
  • Sow cleome seeds on a windowsill indoors or in an unheated greenhouse — they need fluctuating temperatures to germinate and this ensures they’ll get a drop in temperature at night. 
  • Sow value annual & value perennial & biennial seeds for a cost-effective way to add colour to your garden. Read our dedicated guide and learn how to sow biennials & perennials.
  • Plant begonia tubers in the greenhouse this month, positioning them just below the compost surface with the indented side facing upwards. Visit our comprehensive hub page for more advice and tips on growing begonias from tubers or from seed.
  • Repot orchids and other house plants before they start into active growth again.
  • Start climbing annuals, like Thunbergia 'Arizona Trio' indoors for beautiful displays around pergolas & fences over the summer.

Direct sow outdoors

Plant outdoors

pink and white hyacinths growing indoors

Plant forced winter hyacinths outside in March for spring colour next year.
Image: Sarycheva Olesia/Shutterstock

  • Plant bare-root roses straight into their flowering position.
  • Continue to plant deciduous trees.
  • Plant out any forced flower bulbs, such as hyacinths and daffodils, which have finished flowering indoors. These will flower in the garden next spring.
  • Lift and divide established perennial plants - this improves vigour and will create new plants for your garden.
  • Plant summer-flowering bulbs such as gladiolus, lilies and ranunculus into beds, borders and containers. Lily bulbs should be planted at 3 times their own length - this will protect them from heat and improve stability.
  • Snowdrops are usually planted in Autumn, however 'Snowdrops in the green' can be planted in spring to brighten up your winter garden next year. Best planted in shady moist areas of the garden.
  • Plant border perennials such as agapanthus and alstroemeria for spectacular summer colour - great for cut flowers in the house too. Or try our ‘perfect for pollinators’ perennial selection to attract beneficial insects to the spring and summer garden. For more information about growing your own perennials, check out our comprehensive hub page.

Vegetables and herbs to sow and grow

Broad Bean 'The Sutton' by Thompson & Morgan

Sow early broad bean varieties direct into the veg garden in March.
Image: Broad Bean 'The Sutton' by Thompson & Morgan

In the greenhouse / indoors

  • Start off aubergine, sweet pepper, cucumbers, gherkins and mild chilli seeds in the propagator — these plants can stay in the greenhouse over summer. 
  • Plant a variety of tomato seeds under glass for greenhouse cultivation. Check out our tomato selector guide before ordering your seeds to help you choose from a range of sizes, colours and flavours.
  • Start tender celery in seed trays in the greenhouse.
  • Sow celeriac seeds under cover — they need a long growing season.
  • Start winter brassicas like cauliflower and Brussels sprouts in a cold greenhouse ready to plant out later in spring. 
  • Sow salad seeds in pots and place on the windowsill for fresh, healthy leaves. Try recycling yoghurt pots to use as containers.
  • Start basil seeds on your kitchen windowsill. They can stay indoors or be planted out when the risk of frost has passed. 
  • Sow seeds for perennial herbs such as lemon balm, rosemary, sage, oregano and thyme under cover.
  • Begin chitting (sprouting) seed potatoes on delivery.

In the cold frame/ under cloches

  • Sow lettuce and radish seeds into the garden under cloches for your first salad of the season. For advice on how to successfully grow under cloches, read our cloches and mini cloches guide.

Direct sow outdoors

  • Sow early varieties of broad beans like 'The Sutton or 'De Monica'.
  • Sow beetroot, carrot, chicory, Swiss chard, spinach and spring-onion directly into light, stone-free soil for summer cropping. If mice are a problem, sow seeds into modules for potting out after seedlings have developed true leaves. 
  • Sow turnip seeds in rows 30cm apart when the soil is workable - this will provide an early crop. Try 'Milan Purple Top' for attractive purple roots and edible leaves.
  • Try sowing kohl rabi outdoors, for something unusual and fast maturing - remember to provide plenty of water as the stems swell. All parts of this versatile vegetable are edible.
  • Sow early pea varieties such as 'Avola' which has a compact habit and will suit pots on the patio or even hanging baskets.
  • For late summer/early autumn cropping try sowing kale seeds and autumn cabbages such as 'Champion' and 'Greyhound'
  • Start herb seeds off in the kitchen garden - direct sow well-known favourites like chives, coriander, dill and parsley. Or try something new - sow the herb 'Good King Henry' as an alternative to spinach, or bronze fennel for edible foliage, seeds and bulb.

Plant outdoors

Onion 'Jet Set' F1 (Spring) from Thompson & Morgan

If the ground's not frozen, plant out onion, shallot and garlic sets
Image: Onion 'Jet Set' F1 (Spring) from Thompson & Morgan

  • Plant Jerusalem artichoke tubers as soon as the soil is workable, at a depth of 10-15cm. 
  • Plant out asparagus crowns in well-prepared permanent beds. Plant crowns into a trench about 20-25cm deep and 30cm wide. Carefully place the crowns 45cm apart and ensure the emerging buds are just below soil level. These crowns will crop for 25 years after establishment.
  • Plant onion, shallot and garlic sets now in all soils after the risk of frost has passed.
  • Plant chitted early potatoes outside in the ground. If you don't have enough space for growing potatoes on your plot, read our article on how to grow potatoes in bags.

Fruit to sow and grow

Rhubarb 'Champagne' by Thompson & Morgan

Rhubarb crowns can be planted in March in rich fertile soil.
Image: Rhubarb 'Champagne' by Thompson & Morgan

Plant outdoors

Keep one step ahead — what to order this month:

Alyssum 'Alice Golf Mixed' from Thompson & Morgan

Alyssum 'Alice Golf Mixed' is loved by pollinating insects
Image: Alyssum 'Alice Golf Mixed' from Thompson & Morgan

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