What to Grow in a Greenhouse in August: Tips, Tricks & Top Picks
August might feel like the tail-end of summer, but for greenhouse gardeners across the UK, it’s an ideal time to sow and plant for autumn colour, winter crops, and early spring harvests. If you are stuck for ideas for what to grow in a greenhouse in August in the UK, here’s your guide to 8 plants, 8 fruits, 8 vegetables, plus a unique plant to try – with simple planting tips for each.
8 Plants to Sow or Grow in August
1. Winter-flowering pansies
Sow seeds in seed trays filled with fine compost, lightly cover, and keep moist.
Perfect for pots and borders later on.
2. Cyclamen
Sow seeds in shallow trays, barely cover, and keep in cool, shaded part of greenhouse until they germinate.
Ideal for winter colour.
3. Primulas
Sow in trays; gently press seeds onto moist compost surface without covering, as light aids germination.
4. Sweet peas
Start in deep pots or root trainers, sowing two seeds per pot. Keep in a bright, cool spot.
This gives you sturdy early plants.
5. Coriander & parsley
Sow thinly in pots or trays; cover lightly with compost and keep moist.
Cut regularly to encourage fresh growth.
6. Hardy annuals (e.g., calendula, cornflowers)
Sow directly into seed trays or modules, cover lightly, and keep in good light.
7. Lavender cuttings
Take semi-ripe cuttings about 10cm long; strip lower leaves and insert into gritty compost.
Mist regularly.
8. Violas
Sow in trays, cover seeds lightly with compost, and keep moist in dappled shade.
8 Fruits to Grow in the Greenhouse
1. Strawberries
Plant runners into pots or grow bags, spacing them about 30cm apart.
Water regularly.
2. Figs
Pot into large containers with loam-based compost; keep roots slightly restricted to boost fruiting.
3. Grapes
Plant young vines in large tubs or directly into greenhouse border; train along wires.
4. Melons
Sow seeds into pots if you haven’t yet; keep warm, then plant into grow bags.
5. Peaches
Choose dwarf varieties; plant into large containers, keep in bright light, and water evenly.
6. Nectarines
Same as peaches; pot into roomy containers and keep sheltered from cold drafts.
7. Cape gooseberries (physalis)
Plant in pots or grow bags; stake as they grow taller to support branches.
8. Passionfruit
Plant at the base of a trellis or wire frame; tie in shoots as they grow.
8 Vegetables to Sow or Grow in August
1. Winter lettuce
Sow seeds thinly in seed trays or directly into grow bags; cover lightly and keep moist.
2. Spinach
Sow in rows in large pots or directly into greenhouse soil; thin seedlings to avoid crowding.
3. Pak choi
Sow in modules or pots; transplant seedlings when big enough, spacing about 20cm apart.
4. Radishes
Sow directly into pots or shallow troughs; thin seedlings to 2–3cm apart.
5. Spring onions
Sow thinly in drills in pots or trays; keep evenly moist.
6. Carrots (early varieties)
Sow in deep containers filled with sandy, stone-free compost; keep moist.
7. Turnips
Sow directly into pots or borders; thin seedlings to about 10–15cm apart.
8. Swiss chard
Sow in modules; transplant when large enough, spacing about 25–30cm apart.
Unique Plant to Try: Wasabi
For something truly different to grow in a greenhouse in August in the UK, grow wasabi
Plant rhizomes in deep pots filled with moist, rich, well-drained compost; keep in a cool, shady part of your greenhouse and water regularly.
Wasabi takes patience, but it’s a brilliant talking point and a delight for adventurous cooks.
Top Greenhouse Tips for August
- Ventilate daily to reduce fungal disease.
- Shade sensitive seedlings during hot afternoons.
- Feed regularly with a balanced liquid fertiliser.
- Watch for pests: whitefly and red spider mite love late summer warmth.
- Harvest often to encourage more growth.
With these ideas, your greenhouse will stay productive, colourful, and surprising right into autumn and beyond.
Greenhouse Gardeners’ Summer Salad with Wasabi & Melon Dressing
Celebrate your greenhouse harvest with this fresh, vibrant salad – lightly spicy, sweet, and packed with home-grown goodness.
Serves: 2–3
Ready in: 15 minutes
Ingredients (from your greenhouse)
- A few handfuls of winter lettuce leaves and spinach
- 4–6 radishes, thinly sliced
- Small handful of cherry tomatoes or cape gooseberries, halved
- A few sprigs of coriander and parsley, roughly chopped
- ½ small melon (about 200g flesh), cubed
- 1 tsp freshly grated wasabi (or a dab of prepared wasabi paste if yours isn’t mature yet)
For the dressing
- Juice of ½ lime or small lemon
- 1 tbsp olive oil
- 1 tsp runny honey or agave
- Pinch of salt & pepper
Method
- Make the dressing: In a small bowl, mash the melon cubes gently with a fork. Stir in lime juice, olive oil, honey, grated wasabi, salt and pepper. Mix well until it becomes a lightly chunky dressing.
- Assemble the salad: Toss the lettuce, spinach, radishes and cape gooseberries/cherry tomatoes in a large bowl. Add chopped herbs.
- Finish & serve: Drizzle the melon-wasabi dressing over the top and gently toss. Serve immediately with crusty bread or grilled flatbread.
Tip: If you’re harvesting your own wasabi, remember the flavour is freshest when grated just before serving!
This salad captures the essence of a late-summer greenhouse – sweet fruit, crisp greens, fresh herbs and a spicy kick from your unique plant.
Refreshing Greenhouse Fizz
A quick, garden-inspired drink to enjoy on warm August evenings.
Ingredients
- Handful of fresh strawberries or grapes, halved
- A few passionfruit seeds and pulp (or cape gooseberries for a twist)
- Juice of ½ lemon or lime
- Sparkling water or lemonade
- Fresh mint or coriander leaves (for garnish)
- Ice cubes
Method
- Lightly muddle the strawberries or grapes in a glass.
- Add passionfruit pulp and lemon/lime juice.
- Fill with ice, top up with sparkling water or lemonade, and stir gently.
- Garnish with fresh mint or coriander. Enjoy!
August is the perfect time to keep your greenhouse thriving across the UK. In this post, ‘What to grow in a greenhouse in August in the UK’ we explored 8 colourful plants, 8 fruits for sweet harvests, 8 veg for fresh salads and hearty dishes, plus a unique plant – wasabi – for something truly different.
With a little planning and care, your greenhouse can stay productive, colourful, and delicious right into autumn and beyond!