The greenhouse should be set well away from trees. Recommended minimum distance from nearby tree is 30 feet. A wind break such as a hedge is useful on the north and east sides, as strong winds can damage the structure and even ordinary winds will increase the heating bill. The green house should be sited at least 15 ft away from the hedge.

Glass green house should not be set close to the road to a play areas. Other sites to be avoided are waterlogged soils and frost pockets and also recently dug soils. A free standing greenhouse should be located at such a place that electric wiring is possible, and other requirement are also possibly fulfilled. The best site for a lean to type of greenhouse is a west facing wall. A firm and level site is essential and if the structure is larger than 8 ft x 6 ft then a concrete foundation is must.

V. Plants for a Greenhouse

It is difficult to define just what we mean by a green- house plant. There are some plants which live their whole lives within the confines of a greenhouse examples include citrus, jasmine and passion flower, certain varieties of tomatoes cucumbers, short rooted types of carrots, winter and spring varieties of lettuce and certain other vegetables. Then there are others which produce their ornamental display and their crops under glass, but have to start their lines outside the greenhouse or must spend part of their adult life in the open, example are pots of strawberries which are brought into cool green house from garden in January, late flowering chrysanthmums which are brought into the greenhouse in late in late September.

The final group of plants have a life pattern which is just the opposite. They produce the ornamental display or their crops m the garden. For them the greenhouse is a place which provides a protected environment. This is either of the start of their life as seedlings or cuttings or when they are established plants in pots and in need of frost-free conditions. Here one can find seedlings of half hardy vegetables, and bedding plants, cuttings of chrysanthemums and pots of bedding geraniums and fuchsias waiting for the return of frost free night in the spring.

According to the plants grown, greenhouses can be a ornamental greenhouse where there will be no tomatoes or other vegetables and fruits and will be having only flowers as impatiens plumbago, iresine, hypoestis, streptocarpus, begonias etc. Then there can be productive greenhouse where vegetables are grown in pots and growing bags. The third and most popular type of greenhouse is the mixed greenhouse. Here, there are both ornamentals and fruits growing together. Grape wines reach up to the ridge and the benches hold pelargonium, Fuchsia and so on in full flowers.



VI. General Care of Plants in Greenhouse

Growing plants under glass is more time consuming and more challenging than growing the same numbers of plants outdoors. Out of doors the plants rely to a large extent on the natural elements for their needs water, warmth, humidity and so on. Water, warmth and ventilation and so many other requirements of the plants are to be taken care of. For the beginners there are few golden rules. Firstly, the plant should be chosen which are right for the conditions.

Secondly, all the important jobs should be done before, they become critical, like insulation before the first frost arrives, pest management before it becomes out of hand, watering before the leaves droop, shading before the plants get scorched and so on. Next important point is to look and be with the plants to check, feel of the soil, picking off dead flowers, looking under leaves for disease symptoms. An equally important is to maintain hygiene, i.e. to regularly get rid of prunings, dead fruit etc. It also means cleaning of used pots, trays, sprayers, and tools. For following purposes, special care is required in a green- house.

A. Damping down
The traditional method is to use a hose pipe for wetting the floor and benches in summer. As the water evaporates, temperature of the house is lowered and water loss through leaves is also reduced, resulting in lower requirement for frequent watering. Professional growers use electrically driven humidifiers to provide a continuous source of water vapour.

B. Heating
With most greenhouse the comfort level temperature for active healthy growth of plants is 55-75 degree F (12-25 degree C), but this general statement needs to be qualified. Germinating seeds generally need higher temperatures than seedlings and mature plants. If different types of plants are grown, which have different temperature requirements than it is advisable to divide a section of the house with transparent material and then install an adequate heater in the warm section. It is necessary to award as much heat loss as possible during the winter months.

Glass should be kept clean to ensure maximum entry to sun rays. About 80 per cent of the heat is lost through the glass so sides and roof may be lined with polythene sheeting. In spring and summer the problem is reversed. Dry heat is more dangerous than moist heat. As soon as the temperature continually remain above 75 degree F (25 degree C) it is essential to apply some type of shading.

C. Greenhouse Shading
In summer, the greenhouse can become a dead trap for plants. Many plants types are damaged when the temperature stays over 85 degree -90 degree F (30 -34 degree C). Other types of plants such as Begonia, African violet and gloxinia are scorched by summer sunshine. As stated earlier the best answer is a set of outside blinds which can be raised or lowered depending on the weather.

Internal blinds screen stop the entry of harmful rays of the sun, but do not reduce the internal temperature. Most people need a simpler form of shading. Small plants can be placed in the shade of larger ones. Newspaper can be placed over seedlings, rooted cuttings and plants with delicate leaves. Sometimes people use lime wash as a shading paint, this is not recommended as it is difficult to take off when not required.


D. Greenhouse Watering

Among the basic things to remember about watering plants in greenhouse is that roots need air as well as water. It means the compost should be moist but not saturated. The simplest way is to look at the surface of pots daily in summers and weekly in winters. In summer plants may need watering twice a day, in winter they may require water only once a week. Plants need much more water on a sunny day than on a cloudy day and one should avoid watering where sun is shining brightly. There may be some watering troubles also specially in case of pots as mentioned here.

1. Water not absorbed.

Cause: Surface caking
Effect: too much water accumulated in the pot
Symptoms: leaves limp, soft rotten areas, poor growth flowers mouldy, both young and old leaves fall at the same time and roots brown and mushy and mature leaves turn curled yellow and wilted, leaf tips brown.
Cure: Prick out the surface with a fork or miniature towel. Then immerse the pot to compost level in a bucket or bath of water.

2. Water runs straight through the pot

Cause: Shrinkage of compost away from the side of the pot
Effect: too little water available to the plant.
Symptoms: leaves limp and wilted, little or no growth oldest leaves fall first lower leaves curled yellow and wilted, leaf edges brown and dry and flowers fall or quickly fade.
Cure: Immerse the pot to compost level in a bucket or bath of water.


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