An invitation from an 18th-century grandee to “come for a stroll in the winter garden” was likely to have meant stepping not outside but inside, to a glass-covered wonderland of giant ferns and climbers, weird fruits and exotic blooms — in other words, the owner’s conservatory. Those huge glass structures, attached to the house, were built by the wealthy to show off the exciting new plant arrivals from the tropics; winter, when the rest of the garden offered little of interest, was peak viewing time.

The conservatory has had a chequered history since, culminating in the mass market, UPVC-framed glass rooms of recent years that jut out into back gardens and may contain a pot of pelargoniums and a cheese plant but are essentially only brighter versions of living rooms. The trouble with this kind of building, the conservatory plant specialist Lisa Rawley says, is that it is tough on plants. The air is dry and stuffy — the room is ventilated only when someone opens a window — and it can bake in summer and plunge to near freezing in winter. Rawley says: “Plants need fresh air that circulates. They also need humidity — without it the buds fall off — and constant temperatures. I have spent years trying to get plants to perform in such hostile environments, and it’s hard work.”

Last year, though, Rawley’s job was transformed by the arrival of the Plant Conservatory, an elegantly designed and plant-friendly conservatory made by Alitex. Coincidentally another leading greenhouse firm, Hartley Botanic, has also launched a range of what its managing director, Johnny Mobasher, describes as “botanical conservatories”.

Mobasher says: “This range goes forward in terms of design, and backwards in terms of how it’s used. It offers somewhere you can read, paint or hold a party, surrounded by lush foliage and exotic flowers, but it is not carpeted and does not double as a living or dining room.”

Both companies use technology honed from years of successful greenhouse construction: aluminium frames for durability and easy maintenance inside and out, side and roof vents for optimum air flow, and underfloor heating with grills that provide gentle radiant heat rather than the harsh direct blasts given off by wall radiators. Paved or tiled flooring copes with the extra moisture — from misting and watering — that plants grown under glass need.

Both companies have drawn on the glasshouses at Kew for inspiration. Hartley Botanic, which constructed the new Bonsai House for the botanic gardens, has received endorsement to call its range the Kew Conservatory System. The conservatories differ in detail — Alitex’s plant conservatory, which comes in a single design (based on the Thomas Messenger Victorian greenhouses) and size, is double glazed, while the Kew system uses single glazing in a range of styles and colours, incorporating clear span construction to give the conservatories a contemporary look.

Alitex’s display conservatory, at its headquarters near Petersfield in Hampshire, shows how quickly a community of plants can become established, if given the right conditions. Planted up by Rawley in February last year, it is already a jungle of foliage. At one end is a raised bed with inset seating — once you sink into it, you are surrounded by plants. The bed is wide and deep enough to support a lofty “lady palm”, a red-stemmed banana, passion flowers, ferns and other perennials with bold, strongly coloured foliage such as the bushy Eupatorium sordidum with its large heart-shaped leaves and heads of fluffy, fragrant mauve flowers that continue blooming right through winter.

Climbers, planted in big terracotta pots, scramble up the walls, with a glossy stephanotis making a heady frame around the entrance to the house. Several of the plants are beginning to run up into the roof to create a canopy of foliage which, Rawley explains, helps to create the humidity that is essential for many of these exotic plants. The windowsills are wide enough to put seedtrays on and there’s a deep stone sink for soaking pots.

Rawley has included three small fruit trees — an olive, a lemon and an ornamental fig — for impact at the other end of the room but has left the central area clear for furniture and for moving around freely.

One of the chief pleasures of owning a conservatory that is designed for plants is to be able to grow species that would not survive the cold. Why settle for begonias and African violets, asks Rawley, when you could spend winter in your own lush exotic hideaway, among a tangle of vibrant bougainvillaea, passion flower and hibiscus blooms, soothed by the wafting fragrances of heliotropes and mimosas? Why indeed.

Alitex: 01730 826900, www.plant-conservatory.com
Hartley Botanic: 0870 7770320, www.hartleybotanic.co.uk
Lisa Rawley, of Fleur De Lys, grows, plants and maintains conservatory plants: 01798 865475 or e-mail fleurdelisa@tiscali.co.uk

HOT HOUSE

Conservatory plants need:

Shading: necessary in summer and on very sunny days, to prevent scorching of plants and excessive temperatures. External shading does both; internal shading mainly reduces glare.

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