What to Sow and Plant in March (Veg & Flowers) – UK Guide

March marks the true beginning of the growing season in the UK. With longer days and rising soil temperatures, it’s the perfect time to start sowing a wide range of vegetables, herbs and flowers - both under cover and outdoors during mild spells.

This guide highlights what you can confidently sow and plant in March, helping you get a head start on a productive year.

What to Sow Indoors or in a Greenhouse

Many tender crops need warmth to germinate and should be started under cover.

Vegetables

• Tomatoes – Sow in heated propagators or warm windowsills
• Peppers & Chillies – Require consistent warmth
• Aubergines – Slow to germinate, start early
• Courgettes & Squash – Sow towards late March

Herbs

• Basil
• Parsley
• Coriander

Flowers

• Cosmos
• Antirrhinums (Snapdragons)
• Sweet peas

What to Sow Outdoors in March (Weather Permitting)

Hardy vegetables can be sown directly into prepared soil when conditions allow.

• Carrots (early varieties)
• Parsnips
• Spinach
• Beetroot
• Peas and broad beans

Use cloches or fleece to protect young seedlings from frost.

What to Plant in March

Early Potatoes

• Plant chitted tubers in late March
• Earth up as shoots emerge

Onions & Shallots

• Plant onion sets and shallots outdoors
• Choose a sunny, well-drained site

Garlic

• Late planting still possible in early March

Flowers to Sow or Plant Outdoors

• Calendula
• Cornflowers
• Hardy annual mixes

Soil & Weather Tips for March Sowing

• Only sow when soil is workable, not waterlogged
• Warm soil with cloches before sowing
• Ventilate covers on mild days

March offers one of the widest sowing windows of the year. By combining protected sowing with careful outdoor planting, you can build strong, healthy crops that set your garden up for a productive spring and summer.