🌱 What To Plant In January UK: In the Garden and Allotment
January is the heart of winter, and while it’s not a busy sowing month outdoors, it’s an important planning and early-start month for UK gardeners. With the right approach, you can still plant and sow a small but valuable selection of crops — mainly under cover — while setting the groundwork for spring.
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This guide explains what you can plant in January in the UK, both in the garden and on the allotment, and what’s best left until later.
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(What To Plant in January – UK Garden & Allotment)
Using fine, free-draining seed compost is essential for any January indoor sowing. It helps prevent waterlogging and supports healthy germination in cooler winter conditions.
January frosts are common across the UK. Garden fleece helps protect newly planted garlic, broad beans, and overwintering crops from severe cold and wind damage.
Perfect for starting chillies, aubergines, and early flowers indoors in January. Trays and modules make it easier to control warmth, moisture, and spacing during winter sowing.
🌡️ What January Conditions Are Like in the UK
- Frosts are frequent
- Soil is cold, wet, or frozen
- Daylight is short
- Outdoor sowing is very limited
January planting is mostly about protected growing and preparation, not open ground sowing.
🌱 Vegetables You Can Sow Indoors in January
Only sow these if you can provide consistent warmth and good light.
🌶️ Chillies
- Sow indoors with steady heat
- Ideal temperature: 22–28°C
- Slow growers that benefit from a long season
🍆 Aubergines
- Must be started indoors
- Need reliable warmth
- Only suitable if conditions are stable
🌼 Sweet Peas (Optional)
- Can be sown indoors or in a cold greenhouse
- January sowing gives strong early plants
If you can’t provide warmth and light, it’s better to wait until February.
🌱 Vegetables You Can Sow Under Cover
In a greenhouse, cold frame, or polytunnel (weather permitting):
- 🥬 Winter lettuce (hardy varieties)
- 🧅 Onions from seed
- 🥬 Spinach
- 🌱 Mustard greens and salad leaves
Extra protection may be needed during cold snaps.
🌱 Vegetables You Can Plant Outdoors in January
Only if soil is workable and not frozen or waterlogged.
🧄 Garlic
- Can still be planted if missed in autumn
- Grows slowly but reliably
🥔 Broad Beans
- Hardy varieties can be sown outdoors
- Alternatively start in pots under cover
🧅 Onion Sets
- Plant only in mild spells
- Better results often come from February planting
In colder areas, delaying until February or March is usually safer.
🌼 Flowers You Can Sow in January
🌸 Sow Indoors
- Sweet peas
- Begonias
- Geraniums (pelargoniums)
🌼 Sow Under Cover
- Hardy annuals
- Perennials that need a long growing season
🚫 What Not to Plant in January
Avoid sowing:
- Carrots
- Beetroot
- Courgettes
- Beans
- Squash
Cold soil and low light cause poor germination and weak growth.
🪴 Useful January Jobs That Support Planting
- Clean pots and seed trays
- Check seed packets and order early
- Plan crop rotations
- Prepare compost and labels
- Protect overwintering crops from frost
January preparation saves time and mistakes later.
🧠 Key Takeaway
January planting in the UK is about small, careful starts and smart preparation. Focus on indoor and protected sowing, avoid cold soil, and don’t rush crops that need warmth.
What you plant — and plan — in January sets the tone for the whole growing season.