Starting Plants IndoorsSeeds can be germinated and seedlings started in a box, pan or flowerpot of soil in a window. In addition to having at least 6 hours of direct sunlight each day, room must be kept reasonably warm at all times.
Washed fine sand and shredded sphagnum moss are excellent media in which to start seeds. Place a layer of easily drained soil in bottom of a flat and cover this soil with a layer - about three-fourths inch thick - of either fine sand or sphagnum moss. Press sand or moss to form a smooth, firm seedbed.
Then, using a jig, make furrows in seedbed one-half inch deep. Water sand or moss thoroughly and allow it to drain.
Sow seeds thinly in rows and cover seeds lightly with a second layer of sand or moss. Sprinkle flat, preferably with a fine mist, and cover flat with a sheet of clear plastic film. The plastic film diffuses and subdues light and holds moisture in soil and air surrounding seeds. Plastic films offer advantages over glass coverings in that they are light in weight and are nonshattering. Place seeded and covered flat in a location that is reasonably warm at all times and has 6 hours of direct sunlight each day. The flat will require no further attention until after seedlings have developed their first true leaves. They are then ready to transplant to other containers.
It is seldom possible to keep transplanted plants in house windows without their becoming spindling and weak. For healthy growth, place them in a hotbed, coldframe, or other place where they will receive an abundance of sunshine, ample ventilation, and a suitable temperature.
Strong, vigorous seedlings can be started under 40-watt fluorescent tubes. These tubes should be 6 to 8 inches above seedlings. Temperatures should be about 60F at night and 70F during day. Best results are obtained if fluorescent fixture is next to a window to increase amount of light reaching young plants. Soil pellets are simplest and easiest method for starting plants and are readily available from garden supply stores and other sources. Soil pellets are a well-balanced synthetic soil mixture and are free of soilborne diseases and weeds.
Special Devices for Starting Plants In determining type of equipment for starting early plants, gardener must consider temperature and other climatic conditions in his locality, as well as nature of plants to be started. Hardy plants, such as cabbage, need only simple inexpensive facilities, but such heat-loving, tender seedlings as peppers and eggplant must have more elaborate facilities for successful production. In warmer parts of United States, and in well-protected locations elsewhere, a coldframe or a sash-covered pit on sunny side of a building usually suffices. In colder sections, or in exposed areas elsewhere, some form of artificial heat is essential. Where only a little protection against cold damage is needed, a coldframe in which a temporary bank of lamps can be placed may be sufficient. The hotbed, lean-to, or sash greenhouse heated by manure, pipes, flues, or electricity are all widely used, choice depending on conditions. A comparatively small plant-growing structure will provide enough plants for several gardens, and joint efforts by a number of gardeners will usually reduce labor of producing plants. The plant-growing structure should always be on well-drained land free from danger of flooding. A sunny, southern exposure on a moderate slope, with trees, a hedge, a board fence, or other form of windbreak on north and west, makes a desirable site. Plenty of sunshine is necessary. Hotbeds and other plant-growing devices require close attention. They must be ventilated at frequent intervals, and plants may require watering more than once daily. Convenience in handling work is important. Sudden storms may necessitate closing structure within a matter of minutes. Plant growing at home should not be undertaken by persons obliged to be away for extended periods, leaving plant structure unattended. A tight well-glazed structure is necessary where climate is severe; less expensive facilities are satisfactory elsewhere. Covers for hotbeds and coldframes may be glass sash, fiber glass, plastic film, muslin, or light canvas. In moderate and cooler sections of country, standard 3- by 6-foot hotbed sash is most satisfactory. Even this requires supplementary covering with canvas, blankets, mats, or similar material during freezing weather. The amount of covering is determined by degree of heat supplied structure, severity of weather, and kind of plants and their stage of development. Farther South, where less protection is necessary, a muslin cover may be all that is needed and for only a part of time.
Many substitutes for glass as coverings for hotbeds and coldframes are on market. The most widely used substitutes are various kinds of clear plastic film. Some of these have a lifespan of only one season, and others a lifespan of 3 to 5 years. Clear plastic film transmits as much light as glass in visible range, and more than glass in ultraviolet and infrared ranges.
The film comes as flat sheets (on rolls) and in tubular form. Flat-sheet film is used for tacking onto wooden frames; tubular form is used for enclosing metal tubular frames with a tight double layer of film. Large plant hoods made from semicircular aluminum or galvanized steel pipe and fitted with a sleeve of tubular plastic film make excellent coldframes or seasonal row covers. When used in this way, a double layer of plastic film provides an air space that insulates against 4 degrees to 7 degrees of frost temperature change. Electrically heated plant beds are ideal for home gardener, provided electric rates are not too high. The beds may be built any size. Because they are equipped with thermostatic control, they require a minimum of attention. It is not possible to buy frames - completely equipped with heating cables, switches, and thermostats - ready to assemble and set in position. Fill frames with soil or plant boxes and connect to a source of current. Small frames may be removed at end of season and stored; larger frames are usually treated as a permanent installation. For more detailed information, see USDA Leaflet 445, Electric Heating of Hotbeds.