March is the perfect time to get sowing for success this summer.

March is the perfect time to get sowing for success this summer.

What Vegetables to Sow in March in the UK

March is an exciting month for gardeners in the UK, as the longer days and warmer temperatures mark the true beginning of the growing season. It’s a versatile time to sow a wide variety of vegetables, whether indoors, in the greenhouse, or directly outdoors. Here's a comprehensive guide to what you can sow in March, along with tips to ensure your plants thrive.

Indoors or on a Windowsill

Starting seeds indoors in March ensures a head start on the growing season. Use seed trays, pots, and a good-quality seed compost for best results.

1. Tomatoes

  • Why sow now? March is the perfect time for sowing tomatoes for both greenhouse and outdoor growing.

  • Requirements: Sow seeds in small pots or seed trays. Keep them warm (18-21°C) using a propagator or a sunny windowsill.

  • Tip: Prick out seedlings into individual pots when they develop their first true leaves.

2. Peppers (Sweet and Chilli)

  • Why sow now? These crops benefit from a long growing season.

  • Requirements: Maintain a consistent temperature of 20-25°C. Place in a propagator or on a warm windowsill.

  • Tip: Mist seedlings lightly to maintain humidity.

3. Aubergines

  • Why sow now? Aubergines need plenty of time to grow before planting out.

  • Requirements: Sow seeds in pots and place in a warm, bright location. Keep soil consistently moist.

  • Tip: Use a grow light if natural light is insufficient.

4. Cucumbers (for Greenhouse Growing)

  • Why sow now? Early sowing gives you a longer harvesting period.

  • Requirements: Use a propagator or warm room to maintain 20-25°C. Transplant seedlings into larger pots as they grow.

  • Tip: Choose greenhouse varieties like ‘Femspot’ or ‘Telegraph Improved’.

5. Herbs (Basil, Dill, and Parsley)

  • Why sow now? Fresh herbs are easy to grow indoors and add flavour to your meals.

  • Requirements: Sow seeds in small pots on a sunny windowsill. Keep the compost moist but not waterlogged.

  • Tip: Harvest regularly to encourage bushy growth.

In a Greenhouse

A greenhouse is invaluable in March, as it provides protection from frost and helps seeds germinate faster.

6. Lettuce

  • Why sow now? Lettuce grows quickly and can be harvested young.

  • Requirements: Sow seeds in trays or pots and keep in a frost-free greenhouse.

  • Tip: Thin seedlings to allow adequate spacing for growth.

7. Carrots (Early Varieties)

  • Why sow now? Greenhouse sowing helps carrots germinate in the cooler conditions of March.

  • Requirements: Sow in deep containers or greenhouse beds. Maintain soil moisture.

  • Tip: Choose early varieties like ‘Amsterdam Forcing’ for quick results.

8. Spinach

  • Why sow now? Spinach thrives in cooler conditions and grows quickly.

  • Requirements: Sow directly into greenhouse beds or trays. Thin seedlings to avoid overcrowding.

  • Tip: Harvest leaves regularly to encourage new growth.

9. Broad Beans

  • Why sow now? Greenhouse sowing protects young plants from cold weather.

  • Requirements: Use deep pots or root trainers and keep soil moist.

  • Tip: Harden off plants before transplanting outdoors in April.

Outdoors

If the soil is workable and not too wet, you can start sowing hardy vegetables outdoors. Use cloches or fleece to protect young plants from frost.

10. Peas

  • Why sow now? Early sowing ensures a longer harvest period.

  • Requirements: Sow directly into prepared soil or in a trench. Space seeds 5cm apart.

  • Tip: Support plants with netting or sticks as they grow.

11. Onions and Shallots

  • Why sow now? Onions and shallots establish well in early spring.

  • Requirements: Plant sets in well-drained soil, 10-15cm apart.

  • Tip: Cover with fleece if frost is forecast.

12. Parsnips

  • Why sow now? Parsnips need a long growing season and germinate slowly.

  • Requirements: Sow directly into finely raked soil. Keep the area moist.

  • Tip: Mark rows with radish seeds, which germinate quickly and help identify where parsnips are sown.

13. Beetroot

  • Why sow now? Hardy varieties can be sown outdoors under cloches.

  • Requirements: Sow seeds in rows 2.5cm deep and space 10cm apart.

  • Tip: Thin seedlings as they grow to allow roots to develop.

14. Garlic

  • Why sow now? Garlic cloves planted in March will still produce a good harvest.

  • Requirements: Plant cloves in sunny, well-drained soil, 10cm apart with the pointed end up.

  • Tip: Use spring planting varieties like ‘Solent Wight’ for better results.

Specific Tips for Success

  1. Prepare the Soil: Ensure outdoor soil is well-drained and enriched with compost or organic matter.

  2. Warm the Soil: Use cloches or fleece to warm the soil before sowing seeds directly outdoors.

  3. Watering: Keep compost and soil moist but not waterlogged, especially for seeds started indoors or in the greenhouse.

  4. Labeling: Clearly label trays, pots, and rows to avoid confusion later.

  5. Hardening Off: Gradually acclimatize indoor and greenhouse seedlings to outdoor conditions before planting out.

Conclusion

March is a pivotal month for gardeners, offering a mix of indoor, greenhouse, and outdoor sowing opportunities. By choosing the right vegetables and providing optimal growing conditions, you can set yourself up for a productive growing season. 

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