Making the Most of Your Greenhouse

A greenhouse can rightly be described as an investment. Lettuces, cabbages, cauliflowers and others can be raised in the greenhouse early in the year ready for later outdoor planting for early crops. And in summer you can rear cucumbers, tomatoes, melons… the list goes on and on. But it’s not only vegetables that thrive in the greenhouse; plants can be raised from seed, and cuttings propagated by the score; exotic winter plants can be started off, ready to make your garden glow with colour.

Care must be taken in choosing the type of greenhouse. Should the frame be of wood or metal, plastic or concrete? Is it preferable to have glass right to the ground, or should there be a brick or wooden wail up to bench level? Perhaps a good compromise for the average small garden is a greenhouse with glass to the ground but with a bench. Thus you can grow plants under the bench without difficulty and make the most of all the space available.

Now, what about siting the greenhouse? Well, here it depends on what you intend growing. Light is all-important; a greenhouse placed east-west, with its door on the west end, will make the most of spring sunshine – important if you’re raising seedlings or young plants early in the year. A lean-to greenhouse is also well worth considering, especially if you have a south- or west-facing wall which would suit the purpose. There, too, might lie an advantage if you want a heated model. It should be easy to link it with the household heating system, but for goodness’ sake get expert advice and help. Don’t try to install electrical heating in your greenhouse on your own. With damp conditions which prevail in greenhouses, amateur endeavours could have, quite literally, fatal results.

There are other heating methods, of course: solid fuel boilers and hot pipes, paraffin heaters, gas heating… although high air temperature isn’t all that necessary. Root temperature of around 55°F is the chief concern and this can be maintained by electric soil-warming cables. Again, expert advice is needed before these are installed.

Other aids are available. For example, tubular or fan heaters and rod-type thermostats which can control air and soil temperature.

It’s as well, too, to allow for some form of shading. Very strong sun can play havoc with seedlings and other plants. Green plastic roller blinds fitted inside the glass and lowered when necessary are ideal.

Ventilation mustn’t be ignored. Too humid an atmosphere must be avoided because this can be disastrous in its effects on plants. Therefore ventilators should be fitted into the side of the greenhouse; this ensures the movement of air up and out of the top vents of the building.

Problems sometimes arise in greenhouses without heating systems too. They can so easily become damp and stuffy, so proper ventilation must be allowed in order to off-set this. While on the subject of unheated greenhouses, it must be borne in mind that what is grown in them depends on the minimum temperature that can be maintained in winter months. Certainly there’s no problem if the main concern is to grow hardy plants in pots for early flowering. And there are various shrubs — camellias, for example – that benefit from the protection of an unheated greenhouse. Spring bulbs are a good bet too, providing an early mass of colour. Grapes, like ‘Black Hamburgh’ or ‘Foster’s Seedling’, will grow happily, and there’s no reason why melons and cucumbers shouldn’t thrive. Peach trees, grown fan-trained, will also do well, whereas, grown outdoors, their early blossom can be damaged by frost.

It’s inevitable that pests and diseases will invade the greenhouse, but careful, frequent inspection will keep these at bay – under leaves and centres of growing points in plants are the places to keep under observation. Mould and mildew give the most trouble, but proper ventilation should take care of this.

In any discussion regarding greenhouses the tomato must be mentioned. You can grow them from seed, sown in February, or buy plants in the spring. They can be grown in pots or you can buy bags of compost which you simply slit open and then set the young plant on to the compost. By this method plants grow very quickly and are more or less immune from soil-borne diseases. However, tomatoes grown this way must be fed every few days. The results, it is claimed, are fantastic!

Lettuces are another crop very suited to the greenhouse. Sow them direct into the ground in February and, even in an unheated greenhouse, you’ll have a crop ready for salad in April. If, the while, you make successive sowings you can bring seedlings out into the garden, and these planted, say, in April, give you a good start for the main crop. Carrots can be cropped early too, from sowings made direct into the ground in early spring.

Strawberries, planted in pots during the summer and kept outdoors until early spring, can be brought into the greenhouse, where they’ll grow fast and produce crops a month or six weeks ahead of those grown outside. No trouble from birds, either!

Rhubarb, in boxes of compost placed under the greenhouse bench in early spring and covered with black polythene, will produce delicious, mild, sweet stalks.

Chrysanthemums are a greenhouse ‘must’ as well; so are dahlias. You can induce their dormant tubers with growth in March and collect shoots as cuttings from which to form new plants. Also, Alpine plants, orchids and cacti greenhouse-grown provide an endless fascination. So will the simpler processes of growing plants from seed or cuttings.

Truly, life in the greenhouse is never dull.

A greenhouse is essential for any serious gardener. The conventional seems to be the popular choice today, both requiring the minimum of types still hold their own, as does the compact lean-to, bottom left; attention. But there are other designs, some of which are illustrated it’s ideal where space is limited. A cedar or aluminium structure below, and these are rapidly becoming part of today’s scene.

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