Whether you are using the greenhouse or are growing plants in a special room or area in the home, regular attention is essential to success with artificially lighted plants just as with sun-lighted plants.

Try to keep daytime temperatures between 70 and 75 degrees with the usual 10 degree drop during the night. Increase humidity by setting the pots on moistened pea rock. Grow the plants in sterilized soil. Water them regularly, according to the needs of each plant. Spray plants with insecticide every second week, as a preventive. As plants grow, shift them to the next larger sized pot. Leave the lights on flowering plants 12 to 16 hours each day; 4 to 8 hours per day for foliage plants.

If the plants produce long willowy foliage, they are too far from the lights. Set them on boxes or inverted flower pots to boost them closer. If leaves turn yellow and hug the pot, plants are probably getting too much light. Move them farther from the lights.

With stationary fixtures, aim for 18 inches between light tube and plant table to allow head room for plants in 4-inch pots. If you grow larger plants, fasten the lights a greater distance from the table or, better still, operate them on a pulley so you can regulate distances to suit plants.

As you experiment, you will find the proper distances. Here ' is a rather general rule to guide you. Light-loving plants, such as gloxinias and many other tuberous gesneriads, cacti, coleus, and wax begonias grow best with about 8 inches between light fixture and pot rim. African violets, rex begonias, and episcias, among others, thrive when space is about 11 inches. Foliage plants, philodendron, ivy, and cissus can be set 18 to 24 inches from the source of light.

PROPAGATION UNDER LIGHTS

The most popular plants for propagating under lights are the gesneriads. Leaf cuttings or plant divisions can be rooted by inserting them in your favorite rooting mediavermiculite, peatmoss, sand, sphagnum moss, or a mixture of these. You can speed rooting by putting a transparent plastic "tent" over the pots or flats and placing them about 6 to 8 inches from the lights. Transplant the small plants as they appear, which sometimes is but a matter of 3 or 4 weeks.

Tubers and rhizomes can be rooted by placing them on peatmoss, sphagnum moss, or vermiculite. Keep the medium moist and place the planting about 4 to 6 inches from the lights. As soon as sprouts show, transplant the tubers to individual pots.

Start any of the gesneriads from seed by sprinkling the seed over sterilized, milled sphagnum moss, sand, or vermiculite. Cover the planting with a pane of glass or slip it into a transparent plastic bag. Seeds will sprout in a dark, warm area (70 to 75 degrees). As soon as you see the green flecks of new plants, place the planting as close as 3 inches from the light tubes. Here the seedlings will grow with amazing rapidity. By careful timing as to fertilizing and transplanting, you can have flowering gloxinias in 3 to 5 months and African violets in 4 to 6 months.

ADDITIONAL GROWING SPACE

If you want still more room, add fluorescent light setups to the dark areas of your house and turn them into plant-growing spaces. Basements, attics, closets, windowless walls, utility roomsall become propagation areas when supplied with fluorescent lighting.

These lights work on ordinary household current. However, before installing more than a pair or two of them it would be wise to check with your electrical company to find out if your present electrical wiring can stand the additional load.

If you need only a small additional propagation area, you may find it advantageous to buy one of the commercial fluorescent light stands with two to four shelves. A model with three shelves holds two hundred 3-inch pots. There are models available with or without wheels.

PROPAGATION UNDER MIST

Plant physiologists have discovered that a mist like fog of water keeps tender softwood cuttings (cuttings from new growth) in such excellent shape they "just have to root!" Under these conditions of either constant or intermittent mist the cuttings don't wilt and there is a minimum of trouble from fungus and rot.

There is a mist unit on the market that has been adapted from a larger commercial mist-maker system. It's called the Mistic Bubble and is an excellent greenhouse space stretcher. This is a system for rooting soft cuttings outdoors, in sand under plastic with the use of electronically controlled mist. Harvey M. Templeton, Jr., Winchester, Tennessee, is the inventor of the system and the control known as the Electronic Leaf. With this portable system the plants get water automatically, as they need it, until rooting takes place. Then the temporary greenhouse cover is gradually removed and the plants are thus hardened to growing outside in the full sunlight.

The hemispherical shape of the Mistic Bubble is designed to let in light evenly all around as long as the sun hits the cover. The plastic covering has a pigment cast into it to protect the cuttings from excessive summer heat. The low capacity mist nozzle, using 1 gallons of water per hour, keeps the leaves of the cuttings wet at all times, promoting very rapid rooting.

The Mistic Bubble is 4 feet in diameter and has 12 square feet of planting spaceit will hold 1000 cuttings at a time. After they root the cuttings can be sold or planted out to grow to maturity. In the South, the Bubble can be used throughout the year.

We are installing one of these units to use for propagation of herbaceous plants and conifer cuttings, which we will plant out as a basis of a profit-making nursery. We'll start by lining out several hundred daylilies and iris plus a few rows of evergreens. Later we may include chrysanthemums (these too can be rooted in the Mistic Bubble), and a few Azalea mollis, the hardy species, which several dealers now carry and which can stand our hard Minnesota winters.

I have described this system not only because I've had experience with it but also because its basic principles apply generally to mist propagation in the greenhouse as well as in a purchased or homemade propagating case. Fog nozzles for water lines are available for those who wish to make their own setups. Complete mist propagation kits are on the market too.