What Seeds to Sow in March (UK Growing Guide)
March is one of the most exciting months for gardeners in the UK. As the days get longer and temperatures slowly rise, it's the perfect time to start sowing seeds for the growing season ahead.
Some crops should be started indoors for an early start, while others can be sown directly outdoors if the soil conditions allow. Starting seeds now means strong, healthy plants ready for planting out once the risk of frost has passed.
In this guide we’ll cover the best vegetables to sow in March and how to give them the best start.
Seeds to Sow Indoors in March
Tomatoes are one of the most popular crops to start in March. Sow seeds indoors in seed trays or small pots and place them in a warm, bright location. Using a propagation tray with a humidity dome can help create the ideal environment for germination.
Tomatoes
Tomatoes are one of the most popular crops to start in March. Sow seeds indoors in trays or small pots and place them in a warm, bright location.
Tips
- Germinate at around 18–22°C
- Use a propagation tray or small pots
- Provide strong light to prevent leggy seedlings
Tomato seedlings can usually be transplanted outdoors in late May or early June once frost risk has passed.
Peppers and Chillies
Peppers and chillies benefit from an early start because they need a long growing season.
Tips
- Keep temperatures warm (20–25°C if possible)
- A heated propagator can help improve germination
- Grow under lights or on a sunny windowsill
Courgettes
Courgettes grow quickly, so they can also be started indoors toward the end of March.
Tips
- Sow one seed per pot
- Use a light seed compost
- Keep soil moist but not waterlogged
Aubergines
Aubergines require warmth and plenty of light. Starting them in March gives them enough time to develop before the summer.
Using grow lights can help seedlings grow strong if natural light is limited.
Seeds to Sow Outdoors in March
If the soil is workable and not frozen or waterlogged, many hardy vegetables can be sown directly outdoors.
Carrots
Carrots can be sown outdoors from March onwards.
Tips
- Choose a well-drained, stone-free soil
- Sow thinly to avoid overcrowding
- Cover with fleece if frost is expected
Beetroot
Beetroot is easy to grow and can be sown directly into garden beds.
Tips
- Sow in rows about 30cm apart
- Thin seedlings once they appear
- Harvest young roots for the best flavour
Spinach
Spinach grows well in the cool temperatures of early spring.
Tips
- Sow little and often
- Harvest young leaves for salads
- Keep soil consistently moist
Peas
Peas can be sown outdoors in March if the soil is workable.
Tips
- Use supports such as canes or netting
- Protect seedlings from birds
- Sow succession crops for a longer harvest
Radishes
Radishes are one of the fastest crops you can grow and are perfect for beginners.
Tips
- Germinate quickly in cool soil
- Harvest within 4–6 weeks
- Great for succession planting
Tips for Successful Seed Starting
Starting seeds successfully is often about controlling a few key factors.
Temperature
Most seeds germinate best between 18–22°C.
Light
Seedlings need plenty of light to grow strong and healthy. If natural light is limited, LED grow lights can help prevent leggy growth.
Moisture
Keep compost moist but avoid overwatering. Too much water can lead to damping-off disease.
Good Compost
Use a fine seed compost for best germination results.
Useful Equipment for Starting Seeds
Starting seeds is easier with the right tools. Many gardeners find the following helpful:
- Propagation trays
- Humidity domes
- Heat mats
- LED grow lights
- Seed compost
These tools help create the ideal environment for strong seedlings.
Final Thoughts
March is the perfect time to start planning your garden for the year ahead. By sowing seeds now, you'll give your plants a strong start and enjoy earlier harvests in the months to come.
Whether you're growing vegetables outdoors, starting seedlings on a windowsill, or using grow lights indoors, a little preparation in March can lead to a productive growing season.
Happy growing!