A greenhouse isn’t just for growing. It’s not just a warm and dry place to sow seeds and grow tomatoes. Think of it as a giant A miniature garden or ecosystem contained within a glass or plastic container. If sealed, self-sustaining terrariums need very little to no maintenance. Small and slow-growing foliage plants, miniature ferns and mosses are great for sealed terrariums, and succulents and cacti for open terrariums. The first example of a terrarium was a Wardian Case, which helped plant collectors bring back and introduce new, exotic plants in the 19th century.
A method of growing new plants from parts of an existing plant, such as sections of root, stem, leaf or bud. When prepared correctly and planted in the right conditions, they can produce roots and eventually become independent plants. There is a wide range of different methods for taking cuttings, depending on the plant and time of year.
Owning or inheriting a glasshouse can be a bane or a joy, depending on your level of confidence as a gardener but if you think of it as a glass box, like a trophy display cabinet, in winter it can hold many of your treasured plants. If, like me, you have a glass greenhouse that you walk past every day, and look at from many windows, why not create a glorious display of your favourite plants, which may then tempt you outside during the colder months to check on them.
In this case, I am specifically talking about glasshouses, not plastic-covered polytunnels or greenhouses. Although you can also overwinter plants and grow winter crops in these, they do not retain their heat as well as a glasshouse. You would need to provide additional heating and protection.
Sparkling clean
First things first, give it a good clean, both inside and out. Light levels effect the health of your plants, especially in the darker months of the year. Algae, twigs and fallen leaves can quickly build up in the nooks and crannies on the outside of your greenhouse, so clear gutters and wipe all the glass with a soft cloth (and a gentle touch). It’s also a good time to check for any damage or potential issues with the structure that need repair or replacement.
Where plants have been growing near the glass inside your greenhouse, algae may have built up on the internal glass. Wipe with a soft cloth (I used a very diluted solution of washing-up liquid), being careful not to splash any winter crops growing beneath the glass. We use our greenhouse to grow a crop of winter salads, such as rocket and mizuna, and there is simply nothing better than eating fresh greens from the garden in winter.
Sweep the decks
Both the floor and shelving units will have built up debris and Can refer to either home-made garden compost or seed/potting compost: • Garden compost is a soil improver made from decomposed plant waste, usually in a compost bin or heap. It is added to soil to improve its fertility, structure and water-holding capacity. Seed or potting composts are used for growing seedlings or plants in containers - a wide range of commercially produced peat-free composts are available, made from a mix of various ingredients, such as loam, composted bark, coir and sand, although you can mix your own.
This is a good opportunity to seek out any hiding slugs and snails, who will happily munch their way through your winter larder if you don’t relocate them. It’s amazing how tiny they are when young, and can squeeze into the smallest of spaces. Check the rails, the window openings and give all pots a thorough inspection before bringing them into the greenhouse. Snails and slugs often like to hide and around the hole in the base of the pot. Also check for the grubs of vine weevil, who feed on plant roots.
Create a display
Now comes the fun bit. Rather than think of your greenhouse as an overwinter store, curate your own mini glasshouse display. Lots of us have been tempted to buy more tender and exotic plants for our gardens, but many of these will not withstand freezing, or even close to freezing, temperatures. They need to be overwintered.
Use the RHS Plant Finder to check the hardiness rating of your plants. If it’s H1 then you need a heated greenhouse, if it’s H2 or 3 the plants can cope with a cool or frost-free greenhouse. Some will be fine left in the garden with some Anything that can be decomposed by fungi, bacteria and micro-organisms, so it doesn’t persist indefinitely in the environment. Biodegradable plastics are usually made from plants, such as bamboo, rather than fossil fuels. Ideally, products that claim to be biodegradable should break down quickly and leave nothing harmful behind. However, they may need specific conditions in order to biodegrade successfully or may produce greenhouse gases such as methane in the process.
Heavy pots will need to stand on the ground, but smaller and plastic pots of plants can be placed on the benches. Try to stand these on small pieces of wood or slate to allow air flow, and give them space from each other so leaves don’t touch. This helps keep the plants healthy in the humid environment, which can cause grey mould (botrytis). The introduction of outdoor air into a space, for example, a greenhouse. This airflow can reduce temperature, replenish the gases absorbed by plants and keep down fungal diseases like grey moulds.
Plants that need a winter home
This depends on where you live. I am in West Cornwall, which rarely suffers heavy frosts, so I bring my scented pelargoniums into the greenhouse, still in flower, and some pots of borderline tender Osteospermum. Tender A group of plants that have thick, fleshy leaves or stems that are able to store water. This allows them to survive in arid habitats with low moisture.
A soft, fibrous, translucent material laid over or around plants hastening their growth and protecting them against weather and pests. Heavier grades of fleece give about 2°C of protection from frost. It is usually used without supporting hoops.
Where you live it might not be suitable to have these plants in an unheated glasshouse, but you could consider having pots of hardy plants such as chysanthemums, cyclamen, violas, pansies and early These are fleshy, rounded, underground storage organs, usually sold and planted while dormant. Examples include daffodils, tulips, hyacinths, lilies, onions and garlic. The term is often used to cover other underground storage organs, including corms, tubers and rhizomes.
This brings me to the fact that we can no longer presume our weather will do what we think it will. Where once we had cold, snowy winters, we now have mild wet ones, but a sharp snap of frost is just around the corner. Best policy is to be prepared. Have covers at the ready, and make ‘insurance’ plants - I’ve done this with a gorgeous Bulbine frutescens, a new plant this year that I thoroughly recommend for its easy nature and pretty orange flowers.
This plant is so easy to take offsets from, simply by pulling off a section and either putting straight into the ground or into pots of gritty, peat-free compost. Mine rooted and even started flowering within a couple of weeks. I have a few of these, as well as baby aeoniums, safely snuggled in my greenhouse, ready to battle it out this winter.
Before you know it, spring will be here and you’ll be able to start the coming seasons seed sowings. May it be a warm and sunny one.
