The effect of daylight hours on blooming plants has long been recognized by scientists who have done research on plant growth habits. It’s known that some plants are triggered to bloom by short days (chrysanthemums, for example); others including most all of the garden annuals, by longer days. under cabinet lights A third group, and most house plants are in this one, seem to be unaffected by day length. But it is a well-known fact that all plants need a period of darkness in each 24-hour period. For this reason, it is important to establish a regular schedule for turning the lights on and off in your garden under lights.
To help you do this accurately, an automatic timer, which you can set to turn lights on and off at the times you choose, is an item that is well worth the money. Most flowering plants need about 16 hours of artificial light, while foliage plants do well on 10 or 12 hours. If you grow a mixture of plants, set the timer for the number of hours needed by the flowering varieties, since a few extra hours will do no harm to the foliage plants.
Other Plant Needs
In addition to light and darkness, plants need more humidity than is available in an average home in winter months. For sizable light gardens, it is worthwhile to install a small fan to keep the air circulating (though not blowing directly onto plants) and one of the cool vapor-type humidifiers, which are capable of putting out from 2 to 10 gallons of water in a 24-hour period.
For small light gardens, humidity can be increased by lining waterproof plant trays with pebbles, sand, vermiculite, or peat moss and by keeping the material moist. Care must be taken that pots don’t stand in water. Excess water will cause root rot for some varieties. Heavy plastic hung over sides of shelves, ends open for circulation, is also effective in raising humidity, but is not attractive if your light garden is located in the lived-in areas of your home.
Still another way to increase humidity is by frequent misting, using water of room temperature. Handy syringe bottles for this purpose are on the market at low cost. Avoid misting after noon, for plants shouldn’t have wet foliage when lights go off.
When feeding plants-under-lights, you can use the same liquid fertilizer that you use for other house plants, diluted in the same proportion and applied at intervals suggested by the manufacturer. Or, since watering is less frequent due to higher humidity, you may wish to do as some experts recommend: feed plants at about one-fourth strength whenever you water them.
If your garden-under-light is an architectural or decorative feature, you can, by choosing foliage plants that tolerate low light, make use of ceiling-level lighting. You can choose from circle-line tubes, panel lighting, and fluorescent as well as incandescent lights mounted in fixtures that are designed to cast light onto plants without producing unpleasant glare in a room.
Excessive heat builds up if large numbers of incandescent bulbs are grouped together in a small area. Through an electrical supply company, you can order 130-volt bulbs, which will be somewhat cooler.
Although very few plants ‘thrive’ under conditions of low artificial light, there are a number of plants that remain attractive for long periods of time. You will do well to make use of the following lists for help in selecting these as well as plants that will flourish under normal light-garden wattage.