Feature: Greenhouses A
s winter approaches, it’s time to take root cuttings from plants, such as Oriental Poppies, Phlox,
Verbascum, ‘Drumstick’ primula’s, shrubs like ‘Japanese Quince’ and exotic ‘Passion Flowers’. Once the leaves have fallen, take a hand fork and carefully tease the soil from around the plant to expose some of the roots. Remove near to the main stem, any that are at least 6mm and as long as possible, but don’t take too many or it weakens the plant. Wash off any soil and cut off any fibrous side roots. Cuttings need to be 5-15cm long. For easy identification, make a straight cut at the end nearest the main stem and an angled cut at the base then dust it with fungicide like sulphur to prevent rotting. Fill pots of peat substitute compost with added grit and make several holes about 5cm apart with a pencil, cane or dibber, insert the cuttings, with the horizontal end just visible at the top, then cover with a thin layer of grit and water. From then on keep the compost moderately moist, don’t overwater it or the roots may rot.
Indoor Christmas flowers 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 16-18degC 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.
Start of the year seeds With the popularity of vegetable growing, it’s important to put seed orders in early. 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. If you have a heated Greenhouse,
aubergines can be sown at 18-21°C late in January 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 21-24°C. Lightly cover geranium
GCU Autumn 2024
Winter greenhouse
gardening tips One of the 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 some useful tips and know- how for greenhouse gardeners this winter
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. If you missed sowing broad beans in autumn, sow some now under glass for an early summer harvest, 5-8cm apart and 2.5cm deep in deep trays of peat multipurpose compost or singly in small pots. Put them in a cool frost-free Greenhouse, and ‘harden off’ before planting outdoors in early spring. ‘The Sutton’ and ‘Robin Hood’ are dwarf and ideal for windy sites; ‘Aquadulce’ and ‘Aquadulce Claudia’ are taller traditional varieties. 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 artist’s 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 pruning If you are growing C. orientalis and C.tangutica; Clematis texensis, Clematis viticella and their cultivars and the large flowered hybrids like ‘Hagley Hybrid’ and ‘Perle d’Azure’, now’s the time to prune. This group flowers in summer and autumn on the current year’s stems, so select the strongest pair of buds near the base and cut just above them to remove all of the previous year’s growth. Feed, water and mulch when the first growth appears and look forward to the first flush of flowers later in the year.
For more help, tips and advice to offer your customers for successful greenhouse gardening, visit the Hartley Botanic website at
https://hartley-botanic.co.uk/ magazine
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