Fruit Trees in the Greenhouse

The idea of growing exotic fruits under glass was popularized by the Victorians, and they created extravagant greenhouses and hothouses to make this possible. However, while we may find it difficult to grow bananas or pineapples, we can enjoy the fruits of hardier varieties of fruits.

Some heat will always be necessary as the blossom and newly-set fruitlets of all so-called hardy fruits are vulnerable to frost. In an unheated greenhouse sun-heat is stored up during the daytime so that the average temperature is well above that prevailing outside.

Also, the plants in an unheated greenhouse are protected from the wind; these two factors alone result in faster growth and earlier flowering. If flowering coincides with heavy frost the blossom will not survive. Therefore, it is important to keep the temperature above 0oC (32oF) during the coldest weather.

A wide variety of fruits can be grown in a greenhouse including peaches, nectarines, figs and grapes. Strawberries are also popular as greenhouse plants as their fruits are available well before they can be bought in the shops (unless they are imported) and they are finished and out of the way before the space is needed for other things.

Strawberries can be raised quite easily in pots in a heated greenhouse. The time at which they can be harvested will be determined by when they are brought inside and the temperature in the greenhouse. A minimum temperature of 13oC (55oF) is needed before the fruits will ripen, so the cost of your strawberries will be determined by the weather and the amount of heat you need to provide.

Even a small greenhouse can house fruit trees if the variety is chosen carefully and they are planted in pots; this restricts the roots so the trees remain small. Pot grown specimens of a variety of fruit trees are well worth the effort in terms of the quality of the fruit that can be grown and the satisfaction they bring to the grower.

Perhaps the most rewarding plant to grow under the protection of a greenhouse is a grape vine. The best greenhouse in which a vine is to be grown is one facing south, but there is no real reason why other aspects should not be successful. Span-roofed, three-quarter span and lean-to greenhouses will produce good crops, as well as house porches. The important thing is that the vine plant should get as much sun as possible, especially during the summer and early autumn.

Many of the best varieties of vines do best in a heated greenhouse, but there is a wide enough selection to choose from when no heat is available. If some heat has been installed, it is an advantage to have some means of keeping the atmosphere moist during the growing season by syringing the plants and the soil underneath them frequently at least once a day. It is not a good practice to spray water on hot pipes and this may result in scorching the young foliage and grapes.

If the soil is light or gravelly, organic matter will help to retain moisture and many gardeners find it an advantage to mulch the surface of the soil with compost during the growing season. A layer 5cm deep over the surface will help to cut down loss of water and reduce the need for frequent watering.

The soil for growing vines should be as fertile as possible. If the soil is naturally fertile and loamy you will only need to add some well-rotted farmyard manure or garden compost before planting the vines.

Vines will not grow well if the soil is water logged at any time, so improving the drainage is essential if the soil is heavy. The soil may benefit from the addition of lime sprinkled over the surface at a rate of 225g per sq m, when the greenhouse is being prepared. Clay, soils can be improved by digging in coarse gravel, sand and well-rotted garden compost. Vines also need potash which can be added by sprinkling wood ash or burnt garden rubbish on the soil. Bonemeal (500g per sq m) will supply potash as well as nitrogen, this can be forked into the surface soil.