Best Green Houses

Managing the climate of a greenhouse is about providing the plants with the right conditions for

growth, flowering and fruiting. What you need to do will therefore depend on the kind of plants

you are growing and the stage they have reached in their life cycle.

Not all plants need exactly the same conditions so the kind of climate will depend on what you

plan to grow in you greenhouse. Some will need high temperatures and high humidity in the

greenhouse. Others will require slightly cooler conditions in the greenhouse.

It is often possible to reach a compromise and provide conditions that will suit most of your

plants most of the time. You will not be able to provide optimum conditions for all the plants in

your greenhouse. But by choosing plants that like similar conditions you will achieve acceptable

results.

For the amateur greenhouse grower some compromises are necessary. If you are growing

commercially that is another matter. A commercial greenhouse must provide an optimum

climate for a specific type of plant. Otherwise you will lose money.

An amateur who is dedicated to a particular species has to make some hard choices. It may be

necessary to sacrifice variety for quality. If your greenhouse is devoted to orchids and only

orchids you can provide the best climatic conditions. If you want to grow other types of plant

you will just have to build another greenhouse.

For most gardeners such hard decisions are not necessary. It is possible to provide a climate

that will suit many plants to some extent. You may also find that you can partition off part of the

greenhouse to create a microclimate. Part of the greenhouse can then have a climate that is

hotter or more humid than the rest.

In a temperate part of the planet where there is a relatively long growing season it is often

possible to have an unheated greenhouse. An unheated greenhouse relies on the sun's rays

and the residual heat stored in the ground to create a climate that is warmer than the outside

environment. This is adequate for raising seeds and for growing vegetables such as tomatoes in

the summer.

Regulating the climate in an unheated greenhouse is mainly a matter of making sure that there

is enough humidity to avoid pests such as white fly and red spider mite and enough ventilation

to avoid mildew and botritus. The lower the Temperature the lower the humidity should be. Air

cannot hold much moisture at low temperature and rot will result if the greenhouse is not

properly ventilated.

Providing some heat will allow a longer growing season. If the greenhouse is heated in the

winter it will be possible to provide a frost-free space for tender plants that live outdoors in the

summer. A small amount of heat will provide a greenhouse climate in which some salads can be

grown all fear round.

The simplest method of achieving a frost free greenhouse is the old fashioned one of placing a

candle in a large plant pot with another one over the top. The plant pots heat up and continue to

give out heat through the night. Your greenhouse will be frost free in several degrees of frost. If

you intend to keep your greenhouse heated all day or if the climate in your region is very cold in

winter you will need to invest in a more complex form of heating. Electric heating is by far the

best option. It can be thermostatically regulated to produce exactly the climate you need.

Electric heating is expensive, but you can reduce heat loss by insulating your greenhouse with

bubble wrap plastic. This is the same kind of material that is used in packaging. You can buy it

in big sheets from garden suppliers. When it is clipped to the inside of the greenhouse it creates

a double glazed environment.

Insulating a greenhouse allows you to maintain higher temperatures in your greenhouse. But

you must be careful about humidity. Some ventilation will still be necessary. Venting the

greenhouse in the middle of the day will control the internal climate. Cheaper forms of heating

exist but any kind of combustion inevitably produces gases that are harmful to plants. They are

best avoided. If you have plenty of wood then you might consider a wood burning stove. Rather

than put such a stove directly in the greenhouse it would be better to use it as a central heating

stove and pipe hot water through your greenhouse.