What to Grow Over Winter in Your Greenhouse – A Complete Step-by-Step Guide
Winter doesn’t have to mean the end of the growing season! With a little planning, you can keep your greenhouse productive over the colder months.
In this complete guide, we’ll explore what to grow over winter in your greenhouse, how to prepare your space, and top tips for keeping your plants healthy and thriving right through until spring.
Why Grow in a Greenhouse Over Winter?
Using a greenhouse in winter gives you several big advantages:
- Extend the growing season: Keep fresh food on your table year-round.
- Protect crops from frost and rain: Hardy crops grow stronger in shelter.
- Start spring sowings earlier: Beat the rush by sowing seeds ahead of time.
- Maximise your greenhouse investment: Make the most of your space even in colder months.
Tip: Even an unheated greenhouse can make a huge difference in temperature and protection!
Key Factors for Successful Winter Greenhouse Growing
To succeed with winter crops, you’ll need to manage:
Light
- Daylight hours are short — use the brightest spots for crops.
Temperature
- Keep your greenhouse well-ventilated but frost-free if possible.
- Use fleece, bubble wrap insulation, or small heaters if needed.
Watering
- Plants need much less water in winter — damp conditions can cause rot.
The Best Crops to Grow Over Winter in Your Greenhouse
Let’s dive into the best vegetables, herbs, and even flowers that thrive in greenhouses during winter.
1. Winter Salads
- Types: Lamb’s lettuce, mizuna, winter purslane, rocket, mustards.
- Sow: September–October (or November under cover).
- Harvest: Leaf-by-leaf through winter.
Tip: Succession sow every few weeks for continuous salads.
2. Spinach
- Varieties: Choose winter-hardy types like ‘Giant Winter’ spinach.
- Sow: September–October.
- Harvest: As baby leaves or full heads in late winter.
Tip: Spinach thrives in cool temperatures but needs good drainage.
3. Spring Onions
- Varieties: ‘White Lisbon Winter Hardy’ is a great choice.
- Sow: August–October.
- Harvest: Early spring, when growth resumes.
Tip: Sow thinly and protect young plants from slugs.
4. Garlic
- Sow: October–November.
- Harvest: Early summer.
- Notes: Greenhouses can give garlic a great head start against very wet winters.
Tip: Choose autumn-planting garlic varieties suited to your local climate.
5. Broad Beans
- Varieties: ‘Aquadulce Claudia’ is a reliable winter variety.
- Sow: Late October–November.
- Harvest: Early crops from late spring.
Tip: Keep the soil well-drained to avoid rot during wet spells.
6. Carrots (for Early Crops)
- Varieties: Choose fast-growing types like ‘Amsterdam Forcing’.
- Sow: Late summer/early autumn for overwintering under cover.
- Harvest: Early spring.
Tip: Sow in deep containers if soil is heavy or compacted.
7. Peas (for Early Pea Shoots)
- Varieties: ‘Meteor’ or ‘Douce Provence’ are great for winter.
- Sow: October–November.
- Harvest: Pea shoots for salads, or let plants mature for an early crop.
Tip: Protect young pea plants from mice!
Herbs You Can Grow Over Winter in Your Greenhouse
Herbs love the protected environment of a winter greenhouse.
Best winter herbs:
- Parsley: Thrives in cool conditions.
- Coriander: Sow successionally for fresh leaves.
- Chervil: Prefers low light and cool temperatures.
- Thyme and rosemary: Ideal in pots — water sparingly.
Tip: Avoid basil in winter — it’s too cold-loving unless you have a heated greenhouse.
Flowers You Can Grow Over Winter
Yes, you can enjoy some blooms too!
Best winter flowers:
- Winter pansies
- Sweet peas (start early for bigger blooms next spring)
- Primroses (ideal for bright winter colour)
Tip: Early sowings under cover lead to stronger plants for early spring planting out.
How to Prepare Your Greenhouse for Winter Crops
1. Clear Out Summer Plants
- Remove all old tomato, cucumber, and pepper plants.
2. Clean and Disinfect
- Scrub benches, pots, and glass to reduce pests and diseases.
3. Improve Ventilation
- Avoid damp, stagnant air to prevent moulds and rots.
4. Insulate If Needed
- Use bubble wrap to line the inside of your greenhouse.
- Install a small, thermostatic heater if you want to grow tender crops.
Watering and Feeding Tips for Winter Growing
- Water sparingly: Only when the topsoil is dry.
- Feed lightly: Winter crops need less fertiliser — once every few weeks is plenty.
- Ventilate on warm days: Prevents damp and fungal problems.
Tip: Always water in the morning, so plants dry off before cold night temperatures.
Conclusion: Keep Growing All Year Round
With a little planning and care, your greenhouse can stay alive and productive right through winter.
By choosing the right crops, protecting your plants, and adjusting your watering and ventilation routines, you can enjoy fresh salads, herbs, and early crops even during the coldest months.
Make the most of your space — and keep your green thumbs working year-round!
Top 10 Questions and Answers about Growing Over Winter in a Greenhouse
1. Do I need to heat my greenhouse to grow in winter?
No, many hardy crops thrive in an unheated greenhouse, though tender plants may need heat.
2. What are the easiest vegetables to grow over winter?
Winter salads, spinach, and broad beans are among the easiest.
3. How often should I water winter greenhouse crops?
Only when necessary — usually once a week or less.
4. Can I grow tomatoes in winter?
Only in a heated greenhouse with artificial lighting — not practical for most home growers.
5. What’s the best way to insulate a greenhouse for winter?
Line the inside with bubble wrap to retain heat while allowing light in.
6. Should I feed winter crops?
Feed lightly once every 4–6 weeks with a balanced fertiliser.
7. Can I sow seeds directly in the greenhouse in winter?
Yes, especially hardy crops like salads and peas.
8. How do I prevent mould and mildew?
Ventilate on mild days and avoid overwatering.
9. Can I grow microgreens in a winter greenhouse?
Yes! They’re quick and need little space or light.
10. When should I start preparing the greenhouse for winter growing?
Clear and clean in September or October to be ready for winter crops.