Tasks for your greenhouse this December

National Trust Stourhead greenhouse in Norway

The temperature in your greenhouse needs to be carefully monitored this month. Frost-free greenhouses should be kept at a minimum night time temperature of 5 – 7°C (42 – 45°F) and a maximum temperature of 13 – 16°C (55 – 60°F) during the day – any warmer may result in weak and lanky plant growth.

Some ventilation will be necessary to remove condensation and keep the air moving inside the greenhouse. Do tackle this carefully though to avoid creating draughts that are prone to causing dangerous drops in temperature and killing plants.

If plants are not in flower, the soil must be kept rather dry at this time of year. This is particularly true for cacti, succulents and pelargonium.  

Pot cyclamen will now be at their best but be sure to only water when the top of the compost is dry to the touch. Onion seed can be sown in a little heat towards the end of the month – your reward will be large onions next summer. Cut down the last of the winter flowering chrysanthemums and store them in their pots underneath the benching. This month is also the time to start taking the first batch of chrysanthemum cuttings.

You may be dreaming of a white Christmas and if snow is forecast, be sure to keep the shades on your greenhouse tightly rolled up on the ridge if you have these fitted to avoid damage to the shade from fallen snow and make sure gutters are free from blockages.

All should be relatively calm and peaceful inside the greenhouse this month, fitting the mood of the season. With this year’s hard work done, you can look forward to all being merry and bright next year!

Tags: greenhouse, Christmas, Winter, Snow, Temperatures, growing