In The Greenhouse This July

July is peak season in the greenhouse. Growth can be explosive, temperatures can spike quickly, and problems like pests and poor ventilation can escalate fast. The aim is to balance warmth with airflow, steady watering, and constant harvesting.

🌡️Ventilate Every Day

Heat build-up is the biggest July issue.

• Open doors, roof vents, and side vents daily.
• Leave vents open overnight if nights are warm.
• Use automatic vent openers if available.

Poor airflow quickly leads to wilted plants, poor pollination, and disease.

☀️ Shade During Hot Days

Direct sun can scorch plants and overheat the greenhouse.

• Use shade paint or shade netting.
• Focus shading on south and west-facing sides.
• Temporary shading (e.g. net curtains or fleece) can help in heatwaves.

Tomatoes, cucumbers, and peppers especially benefit from reduced midday intensity.

💧 Water Consistently (But Don’t Overdo It)

Plants can dry out very quickly in July.

• Water early in the morning or evening.
• Check pots daily—some may need watering twice a day in heatwaves.
• Avoid letting compost completely dry out, especially for tomatoes and cucumbers.

🌶️ Feed Fruiting Crops Regularly

July is heavy fruiting season:

• Tomatoes
• Cucumbers
• Peppers
• Aubergines

Use a high-potash feed (like tomato fertiliser) every 7–14 days, following instructions.

🥒 Keep on Top of Harvesting

Frequent picking encourages more production:

• Harvest tomatoes when fully coloured.
• Pick cucumbers while small and tender.
• Cut courgettes regularly to avoid oversized fruits.
• Harvest beans and chillies as they mature.

🕷️ Watch for Pests Early

Greenhouses are ideal breeding grounds for pests in July:

• Aphids
• Whitefly
• Red spider mites
• Thrips

Act early:

• Use biological controls where possible.
• Remove heavily infested leaves.
• Improve airflow and avoid overcrowding plants.

🎋 Maintain Good Spacing

Overcrowding increases humidity and disease risk.

• Remove weak or excess growth.
• Tie plants neatly to supports.
• Keep foliage off the soil where possible.

🍅 Pollination Help for Fruiting Crops

If you see poor fruit set:

• Gently shake tomato trusses.
• Encourage airflow through open vents.
• For cucumbers, ensure you have a mix of flower types (or hand pollinate if needed).

🍃 Clean Up Regularly

High summer growth means debris builds up fast:

• Remove yellowing leaves.
• Clear fallen fruit and dead plant material.
• This reduces disease and pest pressure.

🥬 Plan for Late Summer Crops

July is a good time to:

• Sow quick crops like lettuce, basil, and rocket in pots.
• Start autumn salad crops.
• Replace any tired early-season plants.

🌬️For Norfolk Conditions

In Norfolk’s often bright, dry July weather:

• Overheating can happen quickly—ventilation is more important than watering alone.
• Greenhouses can dry out very fast in windy conditions.
• Shade netting is often more effective than heavy watering alone during heatwaves.
• Keep an eye on water supplies if relying on rainwater collection.