In The Greenhouse This October

October in marks a big seasonal shift in the greenhouse, moving from active growing to protection and preparation. As outside temperatures drop and daylight shortens, your greenhouse becomes a vital space for extending the growing season, overwintering tender plants, and starting crops for spring.

Here are the top greenhouse tips for October:

🌡️ Monitor Temperatures & Add Insulation 

• Nights are getting colder — check your minimum temperature daily.
• Install bubble wrap insulation on the inside of the greenhouse to retain warmth.
• Consider adding automatic vents or heaters if you want to maintain growth.

🛠️ Tip: Use a max/min thermometer to monitor fluctuations.

🌱 Sow Cold-Tolerant Crops 

October is a great time to sow hardy crops under cover, such as:

• Winter lettuce, mizuna, mustard, rocket
• Spring onions
• Spinach, chard, lamb’s lettuce
• Broad beans (‘Aquadulce Claudia’ for overwintering)
• Peas (early varieties for overwintering in mild areas)

🌤️ Sow into modules or trays to establish strong young plants. 

🌼 Overwinter Tender Plants 

• Move tender perennials (e.g. pelargoniums, fuchsias, citrus, chillies) into the greenhouse before first frosts.
• Reduce watering and feeding — let them rest.
• Raise pots off the ground to improve air circulation. 

🚫 Don’t let plants sit in water — this can cause rot. 

🧹 Clean & Tidy Thoroughly 

• Wash down glass inside and out to maximise autumn/winter light.
• Clear out dead plants, old compost, and debris.
• Disinfect benches, pots, and trays to reduce pests and diseases.

🐛 Watch for Pests 

• Check for whitefly, aphids, red spider mites, and fungus gnats.
• Use sticky traps, regular inspections, and biological controls if needed.

🍂 Ventilate on dry days to prevent fungal diseases like grey mould (botrytis). 

🧤 Organise & Prepare for Spring 

• Clean and store tools, trays, and pots.
• Organise seeds, and take stock for early sowings.
• Prepare potting mix and compost bins for spring seed starting.

🔌 Set Up Heat & Light (If Needed) 

• Install or test your heater if you plan to grow over winter.
• Consider grow lights if raising seedlings, especially later in autumn or early winter.

🍅 Finish Harvesting Tender Crops 

• Tomatoes, chillies, aubergines – pick remaining fruit.
• Ripen green tomatoes indoors or use them for chutneys.
• Clear spent plants once they stop producing.

🌸 Take Cuttings (Still Time!) 

• Take cuttings of tender perennials (pelargoniums, salvias, etc.).
• Root them in modules or small pots with gritty compost.

🌾 Sow Sweet Peas (for Early Blooms) 

• October is a great time to start sweet peas under cover for stronger, earlier flowers next year.