In The Greenhouse This March

March is when the greenhouse really comes alive 🌱 — but it’s also a month of big temperature swings (bright sun by day, frost by night). The secret is heat management + steady sowing.

Here are your top March greenhouse jobs:

🌡 1. Manage Temperature Carefully

• Ventilate on sunny days (even if it’s cold outside).

• Close vents mid-afternoon to trap warmth.

• Use bubble wrap insulation if nights are still frosty.

• Aim for:

  • 10–12°C minimum for hardy plants

  • 18–21°C for tender seedlings (tomatoes, peppers)

March sun can overheat a greenhouse surprisingly fast.

🌱 2. Start Sowing in Earnest

Ideal to sow now:

Vegetables

• Tomatoes

• Chillies & peppers

• Aubergines

• Lettuce (for early crops)

• Early cabbage & cauliflower

Flowers

• Cosmos

• Zinnias

• Sweet peas (if not already done)

Label everything — March sowings pile up quickly!

💧 3. Water With Care

• Water in the morning, not evening.

• Avoid soaking compost — cold + wet = rot.

• Bottom-water seedlings where possible.

• Watch for damping-off (seedlings collapsing at soil level).

Air movement is your best defence.

🪴 4. Prick Out Seedlings Promptly

• Move seedlings once they have true leaves.

• Handle by leaves, not stems.

• Pot on before roots become congested.

Strong roots now = better crops later.

🌿 5. Pot Up Overwintered Plants

Refresh compost and lightly feed:

• Pelargoniums

• Fuchsias

• Overwintered herbs

Start increasing watering gradually.

🧽 6. Clean & Check for Pests

• Wipe down staging and glass if not done earlier.

• Check for aphids on soft new growth.

• Watch for whitefly.

• Remove dead leaves promptly.

Good hygiene now prevents big problems later.

🍓 7. Bring Strawberries Under Cover (Optional)

Moving a few pots inside now can give you strawberries weeks earlier — just remember to ventilate for pollination.

❄️ 8. Keep Frost Protection Handy

March nights can still dip below zero.

• Use fleece over tender seedlings.

• Keep pots off the floor (it’s colder there).

• A small thermostatic heater is helpful in colder regions.

Golden March Rule

Think: Sow steadily, protect carefully, ventilate daily.