What to sow, grow, and harvest in your UK polytunnel this month
May is one of the busiest and most exciting months for UK gardeners. With the risk of frost finally behind us (in most regions), polytunnel growers get the best of both worlds: the warmth of spring sunshine and the protection of undercover growing. Whether you’re sowing direct, planting out, or keeping earlier crops going strong, May is full of potential.
Here’s what to grow in your polytunnel this month.
🌱 Direct Sow in the Polytunnel
These crops can go straight into your polytunnel beds or large containers now:
- Carrots (early and maincrop varieties)
- Beetroot
- French beans (dwarf and climbing)
- Radishes
- Spinach and Swiss chard
- Lettuce, rocket, and mixed salad leaves
🛠️ Tip: Use fleece or mesh to retain moisture and protect young seedlings from pests like flea beetles.
Start Off Undercover
Some heat-loving crops benefit from a little head start under cover, even in May. You can sow them in modules or trays now:
- Courgettes and squash (for transplanting in 3–4 weeks)
- Cucumbers (especially polytunnel varieties)
- Sweetcorn
- Basil and other tender herbs
- Tomatoes (final sowings – or transplant seedlings into their final positions)
🌡️ Polytunnels trap heat beautifully, giving these crops the boost they need before cooler nights return.
Keep Going: Crops Already in the Ground
If you’ve been growing through March and April, now’s the time to keep these crops happy:
- Spring onions – thin them or start harvesting as bunching onions
- Peas – support climbers and keep them well-watered
- Potatoes (earlies) – keep earthing up to protect tubers from light
- Broad beans – pinch out tips to discourage aphids
🧼 Clear out any tired overwintered crops to free up space and reduce risk of mould or pests.
🔧 May Polytunnel Maintenance
- Ventilation: Start opening doors and vents early — it can get hot fast inside
- Mulching: Add compost or straw to help retain moisture as temperatures rise
- Check irrigation: Drip lines or overhead systems will start earning their keep this month
- Shade nets (optional): Useful later in the month if your tunnel bakes in full sun
đź“… Plan Ahead
Sow some extra salads and fast-growing greens now to keep your harvest going into June. It’s also a great time to start planning your summer crop layout – think tomatoes, peppers, aubergines, and chillies.
Keep Growing with The EasyBuild Polytunnel
Whether you’re sowing your first salad or planting out an entire summer setup, a polytunnel gives you more control over your growing space – and more months of fresh harvests.
Not got yours yet?
👉 Try our EasyBuild Configurator and design your tunnel today.
