🍆 Sowing Aubergine Seeds in Cold Houses

A cold house (an unheated greenhouse or structure) can be useful later in the season, but it presents challenges when sowing aubergine seeds. Aubergines are heat-loving plants, and cold house conditions are often too cool for reliable germination, especially early in the year.

This guide explains whether aubergine seeds can be sown in cold houses, the risks involved, and how to improve your chances of success.

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• Seed Trays & Module Pots

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🌡️ Are Cold Houses Warm Enough for Aubergine Seeds?

In most UK conditions, no.

Aubergine seeds require:

• 22–28°C soil temperature to germinate reliably

Cold houses in late winter and early spring often drop well below this, particularly overnight. Even sunny days rarely keep compost warm enough for consistent germination.

📅 When Cold House Sowing Might Work

Cold house sowing can work later in spring when conditions improve.

• Late April to May offers the best chance
• Night temperatures must remain mild
• Daytime warmth must be consistent

Earlier than this, germination is slow, uneven, or fails altogether.

🌱 Problems Caused by Cold House Sowing

Common issues include:

• Delayed or failed germination
• Patchy sprouting
• Seeds rotting in cold, damp compost
• Weak seedlings struggling to establish

These problems are caused by cold compost rather than seed quality.

🏡 Better Approach: Start Indoors, Finish in the Cold House

The most reliable method is to:

• Sow aubergine seeds indoors in mid-February to early March
• Germinate seeds at 22–28°C
• Move seedlings to the cold house later for growing on

This avoids early cold stress while still making use of the cold house.

🌞 Using a Cold House After Germination

Once seedlings are established:

• Cold houses can be used during warm days
• Plants must be protected or brought back indoors at night
• Sudden cold snaps can stall growth

Cold houses are best used for hardening off, not germination.

🌿 Can Added Protection Help?

Some gardeners improve cold house results by:

• Using cloches inside the structure
• Insulating pots from the ground
• Sowing later to match warmer conditions

Even with protection, results are less reliable than indoor sowing.

🧠 Key Takeaway

Cold houses are not suitable for early aubergine seed sowing in the UK. Compost temperatures are usually too low for germination, leading to poor results.

For best success, start aubergine seeds indoors with reliable warmth, then move plants into the cold house once temperatures are consistently higher.