Most gardeners treat the greenhouse as a summer asset. In April and May, it is a nursery: seed trays of tomatoes and chillies, modules of cosmos and zinnias, the tender perennials — pelargoniums, salvias, dahlias in pots — that need a head start before they can face the English summer. By June, it is a production facility: cucumbers climbing strings, peppers ripening in grow bags, the heady, humid smell of tomato leaves that is, for many people, the definitive scent of summer. By October, for most gardeners, the greenhouse is empty. The glass is cleaned. The door is closed. And that is a mistake, because the winter greenhouse — warm and humid when the garden outside is dormant, filled with the particular green light of January and the scent of damp earth — is the best greenhouse of the year.
A greenhouse in winter is not about productivity. It is about presence. It is about having somewhere to go when the garden is too wet to work and the house feels too small. It is a room of one’s own — not quite indoors, not quite out — where the light is different from any other light, diffused through glass and tinged with green, and where the air smells of soil and growth even in the darkest weeks of the year. The Victorians understood this. Their conservatories were not working greenhouses but living spaces — rooms for reading, for taking tea, for escaping the formality of the drawing room while remaining, technically, indoors. The winter greenhouse recovers something of that Victorian sensibility: the greenhouse as a room, not a tool shed.
What to grow
An unheated greenhouse in a temperate climate will not support tomatoes in January. But it will support a surprising amount of life, and the key is to choose plants that thrive in cool, bright conditions rather than warm ones.
Winter salad leaves are the easiest place to start. Mizuna, mibuna, mustard greens, claytonia, and land cress will all germinate in cool conditions and produce leaves through the darkest months as long as they have enough light. Sow them in modules in September, plant them into the greenhouse border or into deep pots in October, and you will be harvesting leaves from November through to March. The flavour is different from summer salads — stronger, more peppery, more mineral — and there is a particular satisfaction in picking a salad in February that you cannot get from a bag of supermarket leaves.
For flowers, the options are fewer but more precious. Paperwhite narcissus, forced in bulb vases or shallow bowls of gravel, will flower in six to eight weeks from planting and fill the greenhouse with their sweet, slightly peppery scent. Start a new batch every two weeks from October to January and you will have flowers continuously from December to March. Hyacinths, prepared bulbs that have been chilled to simulate winter, can be forced in special hyacinth vases — glass vessels with a pinched waist that holds the bulb above the water — and will produce dense, fragrant flower spikes in January and February. Their scent in a cold greenhouse on a grey day is almost too much — in the best possible way.
A pot of sweet peas sown in October and kept in the greenhouse over winter will be strong, stocky plants by March, ready to plant out as soon as the soil warms. They will flower six weeks ahead of spring-sown plants. The variety matters: choose a winter-flowering type like ‘Winter Sunshine’ or ‘Elegance’, which have been bred specifically for short-day conditions.
And then there are the plants that are not productive but simply beautiful in winter. A pot of cyclamen, its marbled leaves and swept-back flowers glowing in the low January light. A clump of snowdrops, lifted from the garden and potted up, so you can look at them closely — really closely — in a way you never do when they are at ground level. A small rosemary bush, which you will be cutting for the kitchen anyway, and which releases its scent at the slightest touch. None of these will change your life. All of them will improve your January.
The ritual
The winter greenhouse is not something you visit once a week. It is something you visit every day, even if only for ten minutes. There is always something to do: a dead leaf to remove, a seedling to check, a pot to turn so it grows straight. The daily visit becomes a ritual, and the ritual becomes the point. It is the closest many gardeners come to a meditation practice — a defined space, a defined time, a set of simple, repetitive actions that require just enough attention to keep the mind from wandering but not so much that they feel like work.
There is also, in the winter greenhouse, a particular kind of hope that the summer greenhouse does not provide. In summer, the greenhouse is a place of plenty — everything is growing, everything is abundant, the problem is keeping up. In winter, the greenhouse is a place of potential. Every seedling is a bet on the future. Every bulb is a promise that spring will come. The gardener who sows sweet peas in October is making an act of faith: that the world will still be turning in April, that there will still be soil to plant them in, that someone will be there to pick the flowers.
The late Christopher Lloyd, who gardened at Great Dixter for over fifty years and who wrote about gardening with more wit and precision than anyone before or since, once observed that ‘the gardener’s is the most optimistic of professions. He bets on the future every time he sows a seed.’ The winter greenhouse is that bet made visible. It is a small glass room full of small green things, and it is the best reason I know to look forward to January.
