10 best plants for greenhouses

In the UK, a greenhouse stretches the season.

They shield crops from treacherous weather conditions and allow gardeners to grow plants that thrive in warmer conditions. You get earlier sowings in late winter/early spring and harvests that run well into autumn – every gardener’s dream. 

But success under glass is mostly about climate control. Depending on the plants, you might need to add shade on bright days to prevent heat stress. You’ll also need to keep a steady watering routine. 

Ultimately, the best plants for a greenhouse are those that can be easily managed. Ready to grow? Let’s look at the 10 best plans for greenhouses with Whitaker’s Garden Centre. 

1. Tomatoes

Plant tomatoes in your greenhouse, and you’ll yield one of the best returns on effort. 

They thrive in a protected, controlled environment and can produce a real abundance of crops over a long season. Just start earlier in spring to reduce the risk of weather damage (and outdoor pests) and extend your harvest well into Autumn. 

Whitaker's tip: Start a couple of weeks earlier under heat to dodge spring cold, then move well-rooted plants into their final spots as the greenhouse warms. 

2. Cucumbers

Purpose-bred greenhouse cucumbers offer an unbeatable crunch. 

Sow indoors with bottom heat; for unheated houses, April sowings are safest. Plant when inside temperatures hold above 21 °C and train vertically with trellises, string or cages to make harvesting easier. 

Whitaker's tip: Mini types such as ‘Mini Munch’ are brilliant for smaller houses. 

3. Sweet peppers

Peppers love plenty of warmth and bright light (which a greenhouse delivers far more reliably than the UK weather). Sow late winter to early spring with heat; pot on progressively and plant into final containers from late spring. 

Whitaker’s tip: Good airflow (roof vents or louvres) plus midday tapping of the flowers aids fruit set in still weather.

4. Chillies

Closely related to peppers but generally faster to flower and fruit, chillies are superb in a UK greenhouse. Sow with warmth from late winter; grow on in bright conditions and plant into 2–3 litre pots (larger for vigorous types).

Whitaker’s tip: Mix heat levels (mild for everyday cooking and a couple of hotter strains), so you’ve always got the right spice to hand through summer and into autumn. 

5. Aubergines

Aubergines (sometimes called ‘Eggplants’) need a long growing season and, in the UK, are usually sown indoors in a warm sunny spot. Start seeds late winter to early spring with heat, or buy young plants. 

Stake early, keep the soil moist, and don’t forget feed with high potash. 

Whitaker’s tip: For consistent results in cooler summers, try grafted aubergines or compact cultivars bred for protected UK growing.

6. Courgettes

From March to May, gardeners can sow courgettes in their greenhouses. Plant in well-fertilised soil (around 1cm deep). Give each plant generous space, steady watering, and regular feeding; pick fruits small and often to keep them coming!

Whitaker’s tip: Is your greenhouse short on floor space? Train one plant up a stout cane and lightly tie the leaf stalks as it grows – it might look a little untidy, but it keeps the foliage off of damp soil. 

7. French beans

Start sowing dwarf or climbing French beans in modules set in the warmth of your greenhouse. 

They thrive in the stable temperatures and will continue to crop for weeks. Climbing types require strings or canes; keep watering even, ventilate in hot spells to prevent flower drop, and pick every couple of days before the pods become stringy.

Whitaker’s tip: After early tomatoes or cucumbers finish, pop in a late sowing of dwarf French beans in growbags.

8. Basil

Basil isn’t hardy. It grows well enough on a greenhouse bench when you sow little and often for fresh leaves. Gardeners should keep compost just moist (not soggy), and pinch out tips to encourage bushy plants and delay flowering. 

Whitaker’s tip: Pair basil with tomatoes in the same grow bag – but place the basil at the bright front edge so you can water it a bit more sparingly than the tomatoes. 

9. Mixed salad leaves (lettuce & spicy leaves)

Curate an endless supply of mixed salad leaves for mealtime. Salad mixes can be sown in shallow trays, troughs, or on a windowsill, and then harvested for baby leaves approximately 2–3 weeks later.

Whitaker’s tip: Use shading/ventilation in high summer to reduce bitterness.

10. Radishes

After something that grows fairly quickly? Radishes are often ready in around four weeks! They tolerate light shade in midsummer, and undercover, you can start earlier and finish later than outdoors.

Whitaker’s tip: Sow thinly and harvest promptly for the best crunch. 

Shop for gardening supplies with Whitaker’s Garden Centre! 

Greenhouse success comes easier with the right materials. From peat-free seed and veg compost and growbags to canes, ties, feeds and watering gear, Whitaker’s Garden Centre has everything under one roof. 

Order today (home delivery available, with free delivery over £150, and local Click & Collect on many items), or pop in during opening hours for friendly, expert help:

Whitaker's Garden Centre

Manchester Road

Prescot

L34 5UD

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