December
Written by Nelly Hall
Welcome to the final instalment of our 2025 Grow Guides, brought to you by our very own Nelly Hall. This month we’re easing into the December “slow” season, embracing the quieter rhythm that comes as the winter solstice approaches. It’s a time to savour the sanctuary of the greenhouse – tidying, cleaning and readying pots and tools for 2026. While considering the basics of heating, overwintering citrus and pelargoniums, and keeping tender plants safe from frost.
Meet the author
Nelly Hall, Director of Growing at Alitex and co-owner with her husband Tom, shapes the brand and leads the creation of our show stands. She works closely with our gardeners to maintain the greenhouses on our show site and enjoys tending to her own Alitex greenhouse at home. What began as a calm escape has grown into a deep passion and hands-on understanding of gardening.
Nelly is the proud owner of an Alitex Mottisfont greenhouse from our National Trust range, powder-coated in Bronze Manganese, with benching on one side and a built in planter on the other. Follow this link to view a tour of the greenhouse.
Where to find out more
Instagram: @nellyatalitex
In December, we’re slowing down and savouring the calm of the greenhouse as the year draws to a close. We’re delighted to share Nelly Hall’s tips for tidying, preparing pots and tools for 2026, overwintering citrus and pelargoniums, and creating a cosy, festive space to unwind while planning next year’s sowings.
FAQs Tending and unwinding
December isn’t about active growing, it’s about protecting what you have and preparing for the year ahead. With light levels at their lowest, most plants naturally slow down, so the focus shifts to maintenance rather than productivity.
In practical terms, this means:
- Tidying and clearing spent plants
- Cleaning pots, trays, and surfaces
- Checking structures, glazing, and ventilation
- Planning layouts and crops for the next season
This quieter work is what sets you up for a smoother, more productive start in spring.
It’s easy to overlook, but winter cleaning plays a big role in plant health. Pests, algae, and diseases can all linger in debris, old pots, and damp corners of the greenhouse.
By taking the time to clean in December, you:
- Reduce the risk of pests carrying into spring
- Improve light levels by clearing glass and surfaces
- Create a healthier environment for early sowings
It’s far easier to deal with these issues now than once new plants are in place.
A greenhouse offers protection, but it doesn’t make plants completely frost-proof. On colder nights, temperatures inside can still drop low enough to damage tender plants.
To manage this, you can:
- Use fleece or covers for added insulation
- Group plants together to retain warmth
- Introduce gentle heating if needed
- Keep the greenhouse well sealed at night
The goal is to maintain a stable environment rather than relying on the structure alone.
Certain plants won’t survive winter outdoors in the UK and benefit from being brought into a greenhouse. Citrus plants and pelargoniums are common examples, both of which are highlighted in this guide.
These plants need:
- Protection from frost
- Reduced watering during slower growth
- Good light exposure, even in winter
Handled correctly, they’ll come back stronger and ready to grow again in spring.
Watering needs drop significantly in December because plant growth slows and evaporation rates are much lower. Overwatering at this time is one of the most common issues.
A better approach is to:
- Check soil moisture before watering
- Water sparingly and less frequently
- Avoid leaving plants sitting in excess water
This helps prevent root rot and keeps plants healthy during dormancy.
With fewer day-to-day tasks, December gives you the space to step back and plan properly. Instead of reacting to the season, you can think ahead about what worked, what didn’t, and what you want to grow next.
This is the time to:
- Review previous crops and yields
- Plan greenhouse layout and spacing
- Order seeds and materials early
Good planning now reduces stress and improves results later.
Absolutely, and this is often overlooked. In winter, the greenhouse becomes less of a production space and more of a retreat. With fewer tasks and a slower pace, it offers a quiet environment to spend time in.
Many gardeners use this period to:
- Enjoy the space without pressure
- Carry out light maintenance tasks
- Reconnect with the process of growing
That balance between productivity and enjoyment is part of what makes greenhouse gardening sustainable long-term.
