Winter Greenhouse Gardening Tips

One of the most wonderful benefits of owning a Glasshouse or Greenhouse is the ability to extend the growing season – even in winter. A Glasshouse also provides an invaluable tool for the propagation of seeds and cuttings and the over-wintering of tender plants. Heritage Glasshouse manufacturer Hartley Botanic has provided The Lady readers with some useful tips and know-how for Greenhouse gardeners this winter, to help them make the most of their Greenhouses even in the coldest months.

DECEMBER: Indoor Christmas flowers

Buy indoor azaleas and poinsettias from the garden centre. Always carry them in a box to prevent them from falling over or being damaged on the journey home.

Start Amaryllis bulbs into growth by watering sparingly at first; just trickle a little tepid water around the bulb, and increase the amount as growth appears. Once they are actively growing, keep them constantly moist but not waterlogged and take care not to get the growth tip wet. They like temperatures between 60-65degF so a warm sunny window is ideal; keep room temperatures cool to prolong the flowering period (this applies to ‘Indian Azalea’s’, ‘Poinsettia’ and ‘Christmas cactus’ too, which should be well away from radiators). Stake the flowering stems carefully to prevent it from falling over and rotate the pot a quarter of a turn each day, then sit back and enjoy the display. Don’t forget to remove any of your houseplants from the windowsill during the night, as they are easily damaged by low temperatures.

JANUARY: Start of the year seeds

With the sudden popularity of gardening, particularly vegetable growing, it is important to put seed orders in early. The sudden increase in demand during lockdown meant that popular varieties sold out quickly and there was a long waiting time on the websites of major suppliers. With several of the ‘big name’ suppliers now owned by one company, consider supporting smaller, independent suppliers – of which there are many – to ensure that we still retain such a wonderful choice, keep the genetic diversity and support small businesses, too. It is a good idea to browse before you buy, so you have a full overview of what’s available.

If you don’t have enough space to grow everything from seed, buy plug plants, which save time, space and reduce Greenhouse heating costs, too. Once you have ordered your seeds and plug plants, write the labels this month and put them together in an elastic band in alphabetical order, then add the date when you sow.

What to Grow

If you have a heated Greenhouse, aubergines can be sown at 18-21°C (65-70°F) late in the month in pots or modules of peat-free seed sowing compost in a propagator. Once the seeds have germinated, grow lights, will maintain compact growth. Antirrhinums, lobelia, can be sown in a heated propagator at a minimum of 21-24C (70-75F). Lightly cover geranium seed with fine grade vermiculite. Begonia should be sown on the surface of moist compost and left uncovered as they need light to germinate. Sow summer cauliflowers and make small sowings of onions, radish and early carrots in a cold Greenhouse towards the end of January. Peas, lettuce and radish can be sown in Greenhouse borders.

Strawberries that were lifted and potted up last summer, can now be brought into the Greenhouse and put on the bench for maximum light. When they start flowering, pollinate them by transferring pollen from one flower to another using a fine artists brush. Keep the compost moist and feed with dilute tomato fertiliser every two weeks to encourage flowering and fruiting. They can be ‘hardened off’ and planted outdoors in mid spring.

February 101


• Wysteria should be pruned now, as they will bleed if left too late

• Hardy evergreen hedges

• Conservatory climbers should be pruned back before birds begin nesting

• Any winter flowering shrubs which have finished flowering

• Apple and pear trees should be pruned by the end of February


• Roses can now be planted – if planting in an area which has previously grown roses, use mycorrhizal fungi to prevent replant disease

• Bare root fruit trees can be planted now if ground is not waterlogged

• Onions, shallots and garlic can be planted towards the end of February

• Lily bulbs can be planted in well-drained, enriched soil


• Parsnips and leeks can continue to be harvested through February

• Brussel sprouts, sprouting broccoli, turnips and leeks can all be harvested


• Prepare vegetable seed beds for spring planting by digging over the soil, incorporating compost and removing any weeds

• Protect blossoms on fruit trees from the cold using frost fleece

• Keep potted outdoor plants raised off the ground to protect from frost

• Encourage early fruiting in strawberries by covering with cloches

If you prefer leaving your garden in the hands of professionals, our specialist recruitment team will find you the perfect candidate; from Housekeepers to Gardeners, Nannies to Carers, we source only the most exceptional candidates for your home. Contact our friendly team today: