Wondering what vegetable seeds to sow in March to get your vegetable garden off to a great start? Here are my top recommendations for what to sow directly outside, start indoors, or sow under heat for your best growing year yet.
I love growing my own vegetables. Growing your own food is one great way to take real positive action against climate change. And growing your own vegetables brings your food miles right down to zero!
However, it can be tricky knowing where to start. You don’t want to waste money on seeds that are not going to grow. If you’re a novice gardener then let me help you out. Here are some pointers on what seeds to sow in March – directly into the soil, inside, and in heat.
The Seeds to Sow Outside in March
The best seeds to sow outside in March are beetroot, early peas, kohlrabi, lettuce, parsnips, early turnips, broad beans, brussels sprouts, leeks, radish, and spinach beets. Here’s how best to grow them:
Sow your seeds 1cm deep into the soil. Space the seeds 10 cm apart, with 30 cm between rows.
Make a flat-bottomed trench around 5cm deep and 15cm wide. Sow the seeds evenly in the trench about 7.5 cm apart, before covering them with a light layer of soil. If you sow a second row, space it at a distance equal to the height of the final pea crop.
Sow seeds, 1 cm deep in rows 30 cm apart.
Sow thinly at a depth of 1cm, leaving 30 cm between rows.
Sow parsnip seeds thinly at depth of 13 mm, at 15cm intervals. If growing in rows, sow each row 30 cm apart.
Sow seeds thinly in a shallow groove of soil, around 1cm deep. If growing in rows, sow each row around 23 to 30cm apart.
Sow broad beans seeds in March at a depth of 5cm, with 20cm between each seed. They are best sown in double rows, with the rows 20cm part.
Sow seeds thinly at a depth of 13mm, with 15cm between rows.
Sow at a depth of 1 cm, 15 cm apart. Leave 30 cm between rows.
Sow seeds thinly at a depth of 1cm, with a spacing of around 2.5 cm between each seed. If sowing in rows, aim for 15 cm between each row.
Sow your seeds 2.5cm apart, at a depth of 1cm. Leave 30 cm between rows.
The Seeds to Sow Undercover in March
Sowing undercover means in a greenhouse. However, if you don’t have a greenhouse, or don’t have space for a greenhouse a simple cloche (a plastic or glass dome) or mini polytunnel will suffice. We use plastic food pots rather than buying cloches to recycle and save money.
Sow summer cabbages and early cauliflowers and carrots seeds undercover in March. Here are my top tips for each vegetable:
Sow at a depth of 2cm, 25 cm apart. Leave 30 cm between rows.
Sow seeds thinly at a depth of 2cm. Depending on the size of the variety you’re growing, rows should be between 15 cm apart for small varieties to 60 cm apart for larger ones.
Thinly sow the seeds, at a depth of 1cm, in rows 15–30 cm apart. Thin out seedlings if necessary – you should aim for your carrot plants to be 5 – 7.5cm apart.
The Seeds to Sow in Heat in March
The best seeds to sow in heat in March are tomatoes, celeriac, peppers, aubergines, and cucumbers.
To sow in heat you can buy electric seed propagators*. If you’re looking for a thriftier option, you can plant seeds in small pots and set them on a sunny windowsill. You can pop a clear plastic bag over them to help trap heat and moisture.
It does mean for a couple of months your windowsills might be overrun with plant pots, however, your efforts will be rewarded later in the summer when you have a substantial bounty of fresh vegetables that you’ve grown with your own fair hands!
Sow in small pots, then either place in a propagator or cover each pot with a clear plastic bag and place on a sunny windowsill. The seedlings need to be kept at around 18°C. Once two true leaves have formed, transplant them into 9cm pots.
Sow celeriac seeds in March in a pot in a propagator, at 15-18°C. Once the seedlings are hardy enough to be handled, transfer the single seedlings to individual small pots. Maintain temperatures of 15-18°C, as excessive cold can lead to premature flowering (bolting).
Sow seeds in small pots. Place the pots in a heated propagator at about 18–21°C, or on a warm windowsill. If you don’t have a heated propagator, cover your pots with a clear plastic bag or clear lid to trap moisture and warmth. Transplant your seedlings into 7.5–9 cm pots when two true leaves have formed.
Sow at 18-21°C in small pots.
Sow cucumber seeds on their side, at a depth of 1cm, in small pots. Keep them warm in a heated propagator, greenhouse, or on a sunny indoor windowsill.
Hopefully, this guide on seeds to sow in March will keep you right this spring. However, it’s not just about the vegetables in March. Sowing some flowers, such as marigolds and nasturtiums at this time of year is also beneficial by way of companion planting. These are good at discouraging pests from eating your precious seedlings, as well as being good at attracting pollinators, such as bees.
What Seeds Are You Sowing This March?
I’m curious, what seeds are you sowing this March? Any hits you’ve had in previous years? Any misses?
Come back soon and visit my post on what seeds to sow in April. In the meantime, happy growing! I also have lots of other useful gardening guides on Moral Fibres. From some great sustainable garden ideas to why you should choose peat-free compost. and how to attract bees to your garden.