How to Grow Perfect Tomatoes in a Greenhouse: A Complete Guide for UK Gardeners

Tomatoes are one of the most satisfying crops to grow in your own garden — and with the help of a greenhouse, you can enjoy earlier harvests, a longer growing season, and even better flavour. Whether you're new to greenhouse gardening or looking to improve your results, this guide covers everything you need to know to grow thriving tomato plants under cover in the UK climate.

Why Use a Greenhouse for Tomatoes in the UK?

Growing tomatoes in a greenhouse offers several advantages, especially with the UK’s unpredictable weather:

• Extended growing season – Start earlier in spring and keep harvesting into autumn.
• Protection from cold, wind, and rain – Tomatoes prefer stable conditions, which a greenhouse provides.
• Better disease and pest control – Keep your crops safe from blight, slugs, and aphids.
• More consistent yields – Enjoy reliable harvests even in cooler or wetter summers.

Essential Tips for Growing Tomatoes Successfully in a Greenhouse

1. Choose the Right Tomato Variety

Not all varieties perform equally well indoors. For greenhouse growing, go for indeterminate (cordon) types that crop over a longer period. Recommended varieties for UK greenhouses include:

• Sungold – Exceptionally sweet cherry tomatoes.
• Gardener’s Delight – Easy and prolific.
• Moneymaker – A traditional favourite in British greenhouses.
• Shirley F1 – Ideal for greenhouse growing in cooler conditions.

For smaller greenhouses or containers, determinate (bush) types like Roma or Totem work well.

2. Prepare the Soil or Compost

Tomatoes need rich, well-draining compost. Whether you grow in raised beds, growbags, or large pots:

• Use a quality peat-free compost enriched with organic matter or tomato fertiliser.
• Don’t reuse last year’s soil to avoid diseases like blight.
• Ensure your pots or containers are at least 30 cm deep and have good drainage.

3. Timing Is Everything

In the UK, start tomato seeds indoors in March or early April. Transplant seedlings into the greenhouse when night temperatures are consistently above 10°C. In unheated greenhouses, this is usually around May.

Daytime temperatures of 21–27°C and good light levels will help your plants thrive.

4. Train and Support Your Plants

Greenhouse tomatoes often grow tall and will need support:

• Use bamboo canes, strings, or wire supports fixed to the greenhouse frame.
• Regularly pinch out side shoots to concentrate energy into fruiting.
• Remove lower leaves as the plant grows to improve airflow.

5. Hand Pollination Helps

Since pollinators are less active in greenhouses, give your plants a hand:

• Shake the flower trusses gently every few days.
• Use a soft brush or electric toothbrush to transfer pollen between flowers.

6. Water Consistently

Tomatoes hate erratic watering. Uneven moisture can lead to:

• Blossom end rot
• Splitting fruit
• Reduced yields

Water in the morning and keep the compost moist but not soggy. Drip irrigation or seep hoses are ideal in greenhouses.

7. Feed for Flavour

Once the first fruits appear, feed your plants with a high-potash liquid tomato fertiliser every 10–14 days. Liquid seaweed, worm compost, or comfrey tea are great organic options.

8. Watch Temperature and Humidity

Ideal growing conditions for tomatoes in the UK greenhouse:

• Daytime temperature: 21–27°C
• Night-time temperature: above 13°C
• Humidity: 60–70%

Use roof vents and side windows to control excess heat and humidity, especially in summer. Good airflow helps prevent mould and fungal issues.

9. Keep an Eye on Pests

In greenhouses, watch for:

• Whitefly
• Aphids
• Spider mites

Use yellow sticky traps, insecticidal soap, or introduce natural predators like ladybirds. Don’t forget to check under leaves and in flower clusters.

10. Harvest Regularly

Pick tomatoes when they are fully coloured and slightly soft to the touch. Regular harvesting encourages the plant to produce more fruit.

Common Greenhouse Tomato Problems & Solutions

Problem	Likely Cause	Solution
Blossom End Rot	Calcium deficiency from irregular watering	Water consistently, add lime or calcium supplement
Leaf Curl	Heat or stress	Ventilate and avoid over-pruning
Powdery Mildew	High humidity and poor airflow	Improve ventilation and space plants well
Yellow Leaves	Overwatering or nutrient deficiency	Adjust feeding and drainage

Why Choose a Bloomcabin Greenhouse for Tomatoes?

Our Bloomcabin aluminium greenhouses with polycarbonate glazing are designed to meet the needs of serious growers across the UK. Here’s why they’re the perfect choice for tomato growing:

? Robust Aluminium Structure

The powder-coated aluminium frame is rust-proof, maintenance-free, and strong enough to support growing systems, hanging baskets, and tomato vines.

? Polycarbonate Glazing

• UV-protected and shatter-resistant
• Excellent light diffusion for even plant growth
• Superior thermal insulation to maintain stable internal temperatures

?️ Ventilation Made Easy

Integrated roof vents, optional side vents, and automated openers ensure excellent air circulation to manage humidity and reduce the risk of mould or overheating.

? Compatible with Growing Systems

Whether you prefer growbags, raised beds, or containers, our greenhouses are compatible with irrigation systems, grow lights, and other accessories.

? Designed for British Gardens

Our models come in various sizes and styles to suit UK gardens — whether you're in the city, countryside, or coast.

Start Growing Your Best Tomatoes Yet

Tomatoes grown in a high-quality greenhouse are sweeter, juicier, and more reliable — even in a British summer. With the right care and a structure that supports your goals, success is just a growing season away.

? Browse our greenhouse range and choose the perfect aluminium model with polycarbonate glazing for your tomatoes.

At Bloomcabin, we’re proud to support home growers with premium-quality greenhouses that last — and help your plants thrive in any season.