With such a motley assortment of plants, I try to keep relative humidity at 75 per cent or higher. The minute the gauge dips below that mark, we wet down the walks and benches. Of course, this happens only on bright, sunny days. During dark, gloomy weather we water and mist as little as possible.
Constant circulation of fresh air is extremely important all year long. Our doors and vents are wide open in summer. On quiet winter days we may open doors or vents just a crack for a short time. Automatic ventilation is a marvelous convenience in late winter and early spring when the sun suddenly seems to get very hot and threatens to scorch everything under the glass.
Soil
Whether a greenhouse garden is a small flat, part of a bench, or a large ground bed, soil should be prepared carefully to suit the kind of plant that will grow in it. You’ll find “recipes” of all kinds in any authoritative greenhouse garden book. Prepared soil mixtures should be at least a foot deep for beds in which you plan to grow plants of moderate size. For fruit trees and other larger plants, make it even deeper.
Fertilizing
The fertilizing schedule which works so well for my house plants, seems to do equally well for my greenhouse plants. I shall stay with it until I find something better. But it does seem possible that a large greenhouse garden, with large areas of carefully prepared and nutritious soil, would probably need feeding slightly less frequently than plants in pots. I shall have to try this, when my dream greenhouse comes true.
Watering
One of the “musts” in my dream greenhouse will be both hot and cold water, and a provision for mixing them as they flow into the hose. Thus, watering will be like a gentle summer rain. I’ll have an extra-fine nozzle to break the stream into a delicate mist. Warmed water in a fine spray surely should not injure tender foliage in any way. And think what fun it would be to water a garden this way, enjoying the slightly musty fragrance of a warm summer night when soil is moistened by rain—and all of this in January when the snow is piled deep in drifts and banks outside the house.
Grooming
These are the little everyday pleasures of gardening in a greenhouse—snipping back a wandering branch, chiding a creeper and pulling it back from crawling over a neighbor, picking off a faded flower, supporting a branch heavily laden with flowers or fruit. It is real fun, and makes the difference between an overgrown mass and a carefully tended garden in which each plant appears at its best and in harmony with the others. Cleanliness—the removal of all organic matter before it rots, the rinsing away of dust and dirt—is the best protective measure against infiltration of insects and disease.