In The Greenhouse This May

The greenhouse in May—is buzzing! Everything’s growing fast, and it’s one of the most productive times of the year. Whether you’re nurturing tomatoes or raising chillies, here are your top tips for managing a greenhouse in May:

🌡️ 1. Watch your temperatures 

• May days can get hot! Open vents and doors on warm days to stop your greenhouse turning into a sauna. 

• Close up again in the evening to keep the warmth in overnight. 

• Use shading (like shade paint or mesh) if it gets too sunny. 

💧 2. Water smartly 

• Water in the morning, not at night—prevents fungal issues and gives plants what they need to power through the day. 

• Keep the soil moist but not soggy—overwatering is a common mistake. 

• Use capillary matting or trays for consistent moisture in seed trays and pots. 

🍅 3. Plant out tender crops 

• It’s time to plant tomatoes, cucumbers, peppers, and aubergines into their final greenhouse positions. 

• Use large pots, grow bags, or border soil (well-prepped with compost and fertiliser). 

• Stake or support as you go—they’ll shoot up fast! 

🌱 4. Keep sowing! 

• Sow succession crops like lettuce, rocket, spring onions, radishes, and herbs in modules or trays. 

• Sow courgettes, pumpkins, and squash for planting out later in the month. 

🐛 5. Ventilate to avoid disease 

• Good airflow helps prevent mildew, botrytis (grey mould), and damping-off in seedlings. 

• Thin out crowded trays and avoid overwatering young plants. 

🐜 6. Watch for pests 

• Aphids, whitefly, and red spider mite love the warm greenhouse conditions. 

• Use yellow sticky traps, introduce beneficial insects (like ladybirds), or use organic sprays if needed. 

🧼 7. Keep it clean 

• Regularly remove dead leaves, spent compost, and fallen debris to reduce pests and diseases. 

• Wipe down staging and sweep the floor once a week if possible. 

🪴 8. Pot on seedlings 

• Check seedlings and young plants regularly—if roots are showing through the bottom or growth is slowing, it’s time to pot them on. 

• Use fresh compost and move them into slightly bigger pots. 

☀️ 9. Harden off outdoor-bound plants 

• Start taking trays of tender veg and bedding plants outside during the day to harden them off before planting out. 

• A cold frame is ideal, but even a sheltered corner will do. 

🌼 10. Keep feeding 

• Once plants are established and actively growing (especially tomatoes, chillies, and cucumbers), start feeding weekly with a balanced liquid feed. 

• Switch to a high-potash feed (like tomato food) once flowering starts.