Garden frames and conservatories are clearly closely related to the greenhouse, offering a considerable degree of overlap – if not being out-and-out alternatives. Although they are all capable – to a greater or lesser degree – of substituting for each other, they all have their own particular strengths and benefits. Understanding this and making use of it opens up a number of opportunities to any gardener interested in growing under glass.
In many ways the garden frame can be viewed as a sort of half-way-house between the greenhouse and the garden proper, which can be a very important role in acclimatising plants raised under glass to their final cooler and less controlled external environment. However, this is not the only use for the garden frame – it can also be invaluable in relieving over-crowding in the greenhouse, or to grow on plants which are then subsequently returned to their more spacious original surroundings.
Traditionally, frames were made of any convenient material – wood, brick or block-work, metal sheets and the like – covered with a glazed removable top, typically consisting of a number of individual small panes of glass and six feet by four feet or more in size. Modern mass produced frames are available in a range of sizes, often as flat-packs, fabricated from wood or aluminium and glazed with Perspex. The dimensions of the frame really depend entirely on the purpose it is intended to serve. For bringing on seedlings and cuttings, for instance, a frame with a front wall of 12 inches rising to around 18 inches at the back will be perfectly adequate; if the frame is to accommodate pot plants, it will obviously need to be somewhat larger.
Unheated frames are ideal for a number of uses throughout the year – raising cuttings at almost any time, hardening off plants raised in the greenhouse before they can be planted out in early summer and providing winter shelter to the likes of calceolarias and other half-hardy plants. In addition, even simply raising seeds in the frame has its advantages – often giving the plants several weeks head start over a straight-forward outdoor sowing.
By contrast, the heated garden frame, with soil-warming cables and air-warming sides, really is a greenhouse in miniature. If it can be set up to maintain temperatures of 13 – 16 degrees C (55 – 60 degrees F) then many of the half-hardy plant seeds can be germinated early in the year or alternatively, good salad crops can also be produced out of season.
Conservatories have undergone something of a transformation in recent years. Old-style conservatories were much nearer to greenhouses – complete with staging and heating pipes – than their modern counterparts, which have far more in common with what were once known as “sun lounges”. Modern conservatories are typically far more light, airy and glassy structures than before and as such, make far more pleasant places to sit in, while also providing the opportunity to have a variety of exotic, warmth loving plants for decoration.
Since so many plants which were once only propagated in greenhouses will grow well in conservatories, there is a bit of a danger of over-stocking. Cramming too much into the conservatory can often detract from what is essentially another room of the house – propagating really being better left as the role of the true greenhouse. However, the conservatory offers almost unparalleled opportunities to show off colourful and exotic hanging baskets – so you certainly need not feel your creativity stifled by the constraints of the available space!
In many ways, the ideal solution is to have a greenhouse, conservatory and garden frame – allowing a significant amount of movement from one to the other. Plants which need a little more heat than the conservatory or frame can routinely provide, for instance, can be grown to their best in the greenhouse and then moved to the conservatory for the summer. In the same way, seedlings germinated under glass can be hardened off in the frame before taking their place in the flower border. Having all the options open to you adds enormously to the potential – as well as the fun – of gardening.