Jean Vernon explores some of the plants that you can nurture under glass through the depths of the British winter.
One of the main reasons for having a greenhouse is to extend the season at both ends. This is especially important over winter and as the season progresses into spring. With the protection of a greenhouse you can start sowing and growing much earlier and get plants ready to fill your garden with colour and inspiration as soon as the weather allows.
Growing under glass offers a protected growing environment for your plants. It’s the perfect place to shelter plants that aren’t fully hardy but it’s also the best place to get growing before everyone else and to overwinter some garden beauties that just wouldn’t survive outdoors.
Some gardeners heat their greenhouse. Others use a heated bench or propagators to offset some of the winter cold. Since the glasshouse is single glazed and will lose this heat very readily I prefer mine to be solar powered all year round and simply allow mine to harness the warmth of every ray of sunshine that hits its glass panels.
My greenhouse plants are not mollycoddled with heat but they do benefit from the protection of its glass frame, its low brick walls and its tiled floor. And many are wrapped in fleece and bubble wrap too when the going gets tough and the temperatures plummet.
These days I don’t even use a heated propagator, I wait until the weather is favourable for sowing seed. It’s also fun to break the rules a bit and see what will and won’t grow early in the season; apart from tender plants most seeds will come up eventually and many will benefit from the head start.
Stars of the greenhouse bench
Even though I don’t heat my greenhouse I can and do still overwinter a few surprisingly tender plants. Smelly pellies, more correctly called scented pelargoniums. They do get some extra insulation, miniscule amounts of water and are kept above the floor on raised benches or shelves where they can be protected underneath too. I have a lemon scented pelargonium that fills the air with its citrusy scent when I brush past it, and my favourite silver leaved Pelargonium sidoides that has rich purple flowers and soft silky foliage.
In January the greenhouse benches are home to a number of pots of spring flowering bulbs already sprouting and showing signs of fat flower buds waiting to burst. The greenhouse forces these spring beauties into flower a few weeks ahead of those in the garden. For me that extends their flowering season and offers a longer feast for my garden bees when I put the plants outside. That’s a win win for everyone in my book.
You can give your potato crop a head start by chitting seed potatoes in your greenhouse. By allowing ‘earlies’ to develop their ‘eyes’ into shoots, you give them the chance to start growing without planting them into the inhospitable soil outside. Once the sprouts have formed and are growing strongly the weather should be warmer and more conducive to planting them out. The plants will establish quickly and the harvest will be earlier than seed potatoes planted unchitted at the same time.
Escape under glass
The winter greenhouse is a great place to potter about when it’s cold and windy outside. There are a few flowers and veg you can start to sow, many in the pea family, which are hardy and will benefit from an early sowing. Sweetpeas really benefit for an early sowing but add edible peas, mangetout and broadbeans to that list and you can be harvesting edible pea sprouts, broadbean leaves and all sorts to supplement your winter salads.
Under glass in my winter greenhouse is a range of perennials sown from seed last season and now sprouting nicely ready for pricking out or potting up when the weather improves and they start to grow strongly. Alongside are biennials in modules and some cuttings all rooted nicely before the cold of winter set in and now ready to plant out when spring finally arrives.
I’ve got pots of herbs, all hardy, but ones that will benefit from a dry compost through the winter to survive like the rosemary that often succumbs to a long cold wet winter outdoors but will survive in the protected climes of the greenhouse. A generous, established pot of Spanish mint that is the ‘mother plant’ for all my mint plants offered as gifts to like minded friends, but also the source of the most amazing fresh leaves that transform teas and infusions with its pungent minty flavour.
The winter greenhouse is a place to escape. A stool or an old chair positioned in its midst gives you space and purpose to sit a while, to plan the garden and greenhouse crops from right within their midst. To pore over seed catalogues and flower brochures and to dream your gardening dreams undisturbed. Sure it can be cold on a winter’s day. But it is protected from the wind and dampens the sounds from outside, enabling you to lose yourself among the plants, breathe in the earthy smells and tidy up ready for spring.