How to Choose the Right Greenhouse


Why do i want a greenhouse? The answers may appear obvious, but it is wise to ask this question. Is the requirement a sun-trap extension to the house with ornamental plants as part of the general ambience and décor? Is it to provide a controlled environment in which to cultivate a specialist range of species? Is it to propagate and grow on a range of plants for the kitchen garden and for the summer-bedding schemes ? Or is it, as is so often attempted, all three and growing room for a few tomato plants besides?


Choosing a Greenhouse

Much the wisest, because it determines the type of greenhouse chosen, is to make the decision as to the expected prime use. But accept in advance that if this is all the glasshouse space available, other things will creep in however strongly the initial feeling was. Of course, the omnipresent spectre of cost comes at an early stage and affects the size, materials and whether the structure is to be custom-built, off-the-peg or do-it-yourself. It becomes highly desirable to discover from advertisements in the gardening press just what is available, and to examine at leisure all the literature you can find.

lean-to greenhouseThe conventional lean-to conservatory leading from a room in the house has much to commend it (they were almost de rigeur on untold thousands of suburban houses of the 1920’s and 1930’s). The method has an origin which began rather grandly with Victorian ‘winter gardens’ full of palms and ferns. In those very different days the conservatory was seen to isolate the house, at least on that side, from the vagaries of a northern climate. Now we see it more as a transition between indoors and outdoors. All three areas have their part to play in agreeable modern living, with movement from one to another being made easy.

Free-standing greenhouses have certain advantages which lean-to’s lack. Light is usually better (this is vital to avoid spindly growth) but there are disadvantages. Heat-loss through wind is greater and the smaller the house the proportionally more of a problem this will be.

So much so that there is little point trying to heat the smallest houses in winter at all; for each time the door is opened half the greenhouse atmosphere is exchanged at a stroke unless it is approached through another building, a garden shed or the garage — in which case it ceases to be free standing.

octagonal greenhouseSmall isolated greenhouses are also not easily sited satisfactorily in the garden. Manufacturers realising this have attempted to help by producing models in different shapes such as the attractive octagons and geodesic domes. But these do not help the difficulties of successfully producing a fine range of plants in a single regime. Such shapes, indeed, are even less easily compartmentalised than conventional greenhouses.



Greenhouse heating is expensive but without a certain amount, to keep the place at least frost-free, cold-weather displays are bound to be at a minimum. The higher the winter minima that can be maintained, the greater the range of plants which will succeed. Whatever is decided as being economically acceptable it is desirable to arrange a small separate section (perhaps no more than a propagating frame with undersoil heating) to be warmer than the rest of the house and a nearby cold frame. Immediately three regimes become available which make possible a progression of growth stages. This is how municipal greenhouses and botanic gardens can keep things looking so well with their range of back-up glass: the same system on a very small scale is possible at home.


Heating Methods

Paraffin — laboursome and potentially lethal to plants.


Gas — free-standing calor gas

Solid-Fuel boiler

Connection to house central heating

Solar Panels


Range of Regimes:

Cold House

Alpines, bulbs in pots, azaleas, dwarf conifers. Cold frame necessary in addition. Late seedling raising. Vine is possible.


Cool House

Winter minimum 4.5°C (40°F). Forced bulbs and spring flowering annuals. Cinerarias, primulas, pelegoniums. Early vegetable seedlings. Half hardy annuals for outdoors.


Temperate House

Winter minimum 10°C (50°F). A few orchids especially cymbidiums, paphiopedilums. Overwintering exotics for summer containers such as daturas, citrus. Winter-flowering primulas and schizanthus. Raising peppers and aubergines.

12. May 2011 by admin
Categories: Greenhouse Gardening | Tags: , | Comments Off on How to Choose the Right Greenhouse


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