Question: Growing under fluorescent lights is not something I really planned on until we had to move and now I’ve lost all my natural growing light. Can you give some growing instructions on using fluorescent grow lights for my African Violets care. Kirsten, Memphis, Tennessee
Answer: Good news… growing under fluorescent lights is not a new method of culture, but it does produce plants (especially African Violets) of unusual character which far outshine similar plants grown in the conventional manner.
This system of culture – growing under lights – consists of growing the violets under a fluorescent grow light and, believe it or not, they can be grown to perfection right in one’s basement where the plants receive no daylight whatsoever!
Years ago (over 50 in fact) a couple, the Genntisson’s in Atlanta, Georgia, did considerable work to determine the best possible conditions under which African violets can be grown to perfection under lights.
They experimented with different grow lights – long before LED grow lights were on the market – of different intensities, with different heights of the fixtures above the plants, with watering and feeding requirements, and even with different soil mixtures.
They learned that soil mixtures, for instance, had to be different for such conditions than those used for ordinary house culture. So, it was by trial and error that finally developed into a system that produced some beautiful plants.
Their plants being grown in the basement got practically no light from the outside, the cutting bed received none at all. The plants depended entirely upon fluorescent tubes for their source of light. The couple started out with just one double lamp unit with reflector, and everything expanded from there. The basics of growing under fluorescent lights has not changed all that much over the years.
Once you see quality of growth of plants like African violets under lights, you will probably be a convert to the fluorescent light growing as a method of plant culture. Here are some things I have noticed about African violets growing under fluorescent lighting:
- Very profuse flowering—some plants have 250 or more flowers open at once.
- Fluorescent light seems to produce larger leaf blades, and shorter petioles. This is a condition that many prefer, for extremely long petioles take up a great deal of lateral space, especially in the Ionantha type.
- The leaves lie flatter than they do under other types of lighting. This tends to produce very interesting foliar patterns, as the leaves spread out in perfect geometric patterns on a horizontal plane. The plants are beautiful in leaf alone.
- The flowers seem to be produced in dense clusters well above the leaves, thus eliminating the difficulty sometimes experienced when leaves often cover up flower clusters, and hide them. The result is a rosette effect.
The over-all perfection of growth of African violets under fluorescent lights is so outstanding that plants were not allowed to be shown in competition with plants grown under other conditions. Special classes are written just for plants grown under artificial light.
If you are growing completely under lights in a basement… a small electric fan can be used to keep the air in circulation, while a thermostatically controlled heater maintains the proper temperature during the winter months.
Another observation has been that plants growing in glass pots tend to sport a great deal more than those grown in regular pots. The sporting was in the form of varying degrees of yellow mottling of the leaves, producing a variegated foliage effect.
Many people who grow plants under fluorescent lights, have excellent results in raising and flowering gloxinias and tuberous-rooted begonias under the same lighting arrangement that they have set up for the violets.
The Technical Side
Now, for the mechanical features of the lighting equipment. Expose plants to the light for 12 to 14 hours a day.
In winter, they are given 16 hours a day. The grow light units can all be connected to an automatic time switch so you won’t need to turn the lights on and off. The timer, could be set to go on at 8:00 a.m., and to shut off at 11:00 p.m.
This way if you take off on vacation, you will only need to someone see that the plants were watered as they needed it – the time switch will take care of the lighting arrangements.
The time switch is an ordinary, inexpensive type used to turn lights on and off at home to make it look like someone is home. Most hardware stores and home improvement centers like Lowe’s and Home Depot should have a time and the fluorescent lights needed for growing.
Fluorescent fixtures with reflectors using use two 40-watt tubes, 48 inches long, in each reflector, providing a total of 80 watts on each staging should work well. Some indoor growers use reflectors closed at the ends, others seem to prefer the open-end reflectors to allow a longer lateral diffusion of light.
Before you get excited about the cost of operating electrical lighting equipment to grow plants the cost is minimal. Some growers even install fluorescent lighting units in their greenhouse.
The lamps were set 18 inches from the floor of each stage. This left a space of 8 to 10 inches above the foliage of the plants. Wherever young plants seemed to be too far from the lamps, Mrs. Genntisson would simply place the pots on fruit juice containers to boost them up closer to the lights. The containers also caught any excessive moisture that would drip through the pots.
Fluorescent growing lamps are placed approximately 10 inches above the leaves.
It has been interesting to learn that the regular soil mixtures for raising African violets in the living-room or porch did not seem to produce such good results when the plants were grown under lights.
After some experimenting, the best results I’ve obtained using a potting mixture is of 1 part vermiculite, 1 part perlite and 2 parts peat moss, your mix may be different. But I would start with a well draining mix. Liquid fertilizer was used in small quantities and excellent results have been seen watering plants from the top and from the bottom under grow lights. Indoors I like to use LECA as my growing media.
Admittedly, I was thoroughly sold on this fluorescent lighting idea, as were all others who have witnessed the “grow light” specimens. Others who have just installed fluorescent lights are enthusiastic over the results of just one week of growth of their plants under fluorescent lighting.