Remember that you are not limited to a certain variety of plants to grow in a greenhouse. Bear in mind, however, that your preference for certain fruits, vegetables and plants will determine the type of greenhouse you like to build. "Know thy crop" is an important factor before deciding on the greenhouse type you will install.

You will need a good soil for planting seeds. Compost, potting or gardening soil and a little sand or perlite are a good start. Read all directions in your seed packets. Keep some of those black plastic flats that nurseries use to display their plant containers. These are useful for starting sees and transplants.

Benches in greenhouses are essential, as they hold trays of plants that have already sprouted from seeds.

Styrofoam cups - have several of these handy. Seeds sprout quickly and once they grow large enough to move into separate containers, they can be gently lifted and transferred into ordinary Styrofoam cups.

You can also use yogurt plastic cups, and large commercial type containers that can hold more than one plant. In fact, any container you can think of will be suitable.

Other materials you should have on hand are broken clay pots, cracked walnuts, marbles, charcoal or gravel. These help in proper drainage. Be sure to soak clay pots in water a few minutes before using them. This will prevent the clay from absorbing the moisture from the potting soil.

If you want to have trellises inside your greenhouse, you can make them out of coat hangers, which you can bend to any shape your heart desires.

Herbs are perfect for keeping pests at bay. They are what one writer calls "nature's insecticides". Have a variety of them inside your greenhouse. You can make a natural insecticide by adding onions or garlic to a jar of water. Leave it for a week and spray on your plants.

Other garden tools that will help you run your greenhouse efficiently are air coolers for the hot summer. This is to maintain the temperatures at desired levels. Power vents in the roof are also a good idea to release hot air that can build up suddenly in the summer.

In the winter, a good heater would be nice to warm the greenhouse. Other accessories you need are a humidifier, a CO2 generator, and a mister.