Fertilizers:

If you use cloth, it can be placed outside as well as inside for cooling and shading. In fact any type of shading used outside, but with an air space between the shading and the glass, will help you operate your greenhouse more economically.

Most growing plants need fertilizing at least twice a month. Liquid fertilizing is very popular. Some growers dilute fertilizer )i or % recommended strength and then give it at weekly intervals. Apply fertilizer to moist soil, for if the soil is dry, the chemical may burn feeder roots and cause a setback.

Types of Plant Food

There are many brands of organic and inorganic fertilizers on the market. If you prefer an organic type, I suggest fish emulsion, Ovene (a stick form of concentrated sheep manure), or liquid manure. You can prepare liquid manure by placing a half bushel of cow manure in a burlap bag and steeping it in a half tub of water for 2 to 3 weeks. Dilute this "brew" with water'to the color of weak tea?and then apply to your greenhouse plants. If you prefer the inorganic fertilizers, choose Ra-pid-gro, Hyponex, Plant Marvel, Spoonit, or something similar.

When plants are resting, they do not need fertilizer. Bulbs? amaryllis, haemanthus, other amaryllids, and tuberous or rhizomatous gesneriads?need no fertilizer and a minimum of water during their dormant period.

A complete commercial fertilizer includes proper proportions of the three main plant foods?nitrogen, phosphorus or phosphoric acid, and potash or potassium (N, P, and K). Percentages are numbered on the container in that order. A favorite with many growers is 5-10-5. This means the fertilizer contains 5 per cent nitrogen, 10 per cent phosphorus, and 5 per cent potash.

Nitrogen helps plants produce heavy stems and good foliage. When soil is deficient in nitrogen, stems are short and weak and leaves turn a sickly greenish yellow.

Phosphorus aids plants in ripening tissues and seed. If you are planning for choice seed lots, include phosphorus (or superphosphate, as it is usually sold in seed stores) in your fertilizer. Some gardeners add super phosphate, a layer a month, to the compost pile.

Potash is to plants what vitamins are to humans. Included in the plant diet, it aids in the formation and transference of starch. Potash helps plants grow huskier with sturdy stems and foliage, "fat" fruits, and strong roots. It is especially desirable for root crops and such potted plants as gloxinias and amaryllis. If you use a 5-10-5 fertilizer, you can give your bulbous plants an additional weekly watering of muriate of potash, )1 teaspoonful to a quart of water.

Shading

Learning when and how to shade my plants was for me the most difficult phase of greenhouse operation. You can purchase various shading compounds (one called Garlands is preferred by many growers). Cement, liquefied with a mixture of water and linseed oil and diluted until it is just thick enough to adhere to glass, seems to work best for me. I brush it on the glass with an old broom extended by a stick fastened to the handle. This shading holds for the summer, even through hard rains, and a small amount adheres during the winter. By spring, when I give the greenhouse the annual housecleaning, the shading has about disappeared and the glass is ready for another coat.

Another effective method is to use slatted shading which rolls up and down like porch shades. Layers of tobacco cloth fastened inside the house also are helpful.

Avoid linseed oil in any shading mixture intended for use on plastic houses. It is difficult to remove, as there is a chemical reaction between the plastic and the oil so that the shading "sinks in," becoming part of the plastic. Houses of polyethylene plastic can be shaded with layers of tobacco cloth or cheesecloth fastened on the inside as well as by plastic screens inside or slat shading on the outside.

One orchid grower places strips of lath about 6 inches above the glass for both shading and cooling. Tinted shading may blend with the paint on your home but white shading is best, since it reflects more heat while allowing more light to pass through.

Since you want plants to reach a saleable stage in minimum time, you will have to pay considerable attention to fertilizing. A regular program is necessary. Decide on dates when you will fertilize plants, then try not to deviate from schedule unless the weather upsets the expected rate of plant development.