Research work and experimentation is developing a rapidly increasing amount of new knowledge and new methods which may revolutionize the art of growing plants.
There has been considerable publicity regarding liquid nutrients, i.e., the growing of plants in water containing various chemicals or in sand watered with nutrient solutions.
Remarkable crops have been produced by these methods – artificial light can be applied with equally good results whether plants are grown in soil or in liquid nutrients.
Unquestionably artificial light is playing a rapidly increasing part in horticulture.
Doubtless the day will come when many of the more valuable plants will be grown in windowless greenhouses made of heat-insulating material. In such a house, advantage will be taken of the ever-increasing efficiency of light sources.
Lamps are now available that operate with much greater efficiency compared to older light bulbs and lamps. The cost of electricity is steadily decreasing. The heat of the lamps can be used to heat the greenhouse in Winter.
Humidity as well as light and temperature will be automatically controlled. Perhaps carbon dioxide will be fed to the plants. Sterilized soil will, of course, be used and probably liquid nutrients.
Under such conditions parasites and plant diseases can be greatly reduced if not entirely eliminated. In the greenhouse of the future it should be possible not only to predict but to regulate almost to a day the blossoming date of any plant.
Considerable attention is being given to growing plants entirely under artificial light, not with the thought that this can be done on a commercially profitable basis, though with ever-increasing efficiencies of light sources and decreasing power costs this may come.
Years ago the U. S. Department of Agriculture tested growing plants entirely under artificial light to eliminate weather, climatic, and seasonable variables, so as to enable them to study plant diseases and develop better methods of control.
Some curious things have been discovered by using different light sources. For example, tomato plants will not grow under continuous illumination from mazda lamps.
However, they have been grown under continuous light from sodium lamps. Under these conditions albino leaves have developed. But if just a little light from a high intensity mercury arc is added to the sodium for as short a period as two hours per day, fine dark foliage develops.
Perhaps the time is not far distant when we shall know the relative effectiveness of each wave length of the visible spectrum for plant growth.
Germicidal lamps use UVC light to sterilize bacteria, mold, fungi, and viruses. With this data maybe light sources can be developed that will be so effective for plant growth that we can grow plants 100 percent indoors on a commercially profitable scale.
by L Porter