Why Spring Greenhouse Preparation Matters
Spring is the most exciting time in the garden — and if you have a greenhouse, it's your secret weapon for getting ahead of the season. Whether you're growing tomatoes, cucumbers, peppers, or tender bedding plants, a well-prepared greenhouse gives your plants the best possible start. This guide walks you through everything you need to do to get your greenhouse ready for 2026's growing season.
Step 1: Clean and Disinfect Your Greenhouse
Before you bring in any new plants or compost, give your greenhouse a thorough clean. Over winter, algae, pests, and disease spores can build up on glass panels, staging, and pots.
- Wash glass panels inside and out with warm soapy water to maximise light transmission
- Scrub staging and shelving with a garden disinfectant
- Remove old compost and debris from the floor
- Check for broken panes and replace them before temperatures drop at night
Step 2: Check Your Greenhouse Structure
Winter weather can take its toll on greenhouse frames and glazing. Before the busy season begins, inspect:
- Frame integrity — look for rust on metal frames or rot on timber frames
- Ventilation — ensure roof vents open and close freely; good airflow prevents fungal disease
- Door seals — draught-proof doors help retain heat on cold spring nights
- Guttering — clear any blockages so rainwater can be collected for watering
Step 3: Set Up Your Staging and Growing Zones
Organise your greenhouse into zones based on heat requirements. Tender seedlings and tropical plants need the warmest spot (usually the centre or near a heater), while hardier plants can go near the sides or door.
- Use tiered staging to maximise vertical space
- Place propagation trays on heated mats for faster germination
- Keep a thermometer at plant level — not just at head height
Step 4: Sowing Your First Seeds
April is the ideal time to sow many warm-season crops under glass in the UK. Here's a quick sowing guide for spring 2026:
- Tomatoes — sow now for planting out in late May/early June
- Cucumbers and courgettes — sow in April, they grow fast
- Peppers and chillies — these need a long season; sow as early as possible
- Basil and tender herbs — keep on a warm windowsill or heated bench
- Bedding plants — petunias, lobelia, and busy lizzies all benefit from an early start
Step 5: Watering and Feeding
As days lengthen and temperatures rise, your greenhouse plants will need more water. Overwatering is the most common mistake — always check the compost before watering. Feed seedlings with a balanced liquid fertiliser once they have their first true leaves.
Step 6: Pest and Disease Watch
Warm, humid conditions in a greenhouse are ideal for pests like whitefly, red spider mite, and aphids. Start monitoring early:
- Introduce biological controls (such as Encarsia for whitefly) as soon as temperatures allow
- Use yellow sticky traps to monitor flying pest populations
- Ensure good ventilation to reduce grey mould (botrytis)
Make the Most of Your Greenhouse This Spring
A greenhouse is one of the best investments a UK gardener can make — extending your growing season by weeks at both ends of the year. With a little preparation now, you'll be harvesting homegrown tomatoes and cucumbers all summer long.
Browse our range of greenhouses and propagation equipment to get fully set up for spring 2026.