When garden consultants, horticultural experts and nurserymen explain what soil and fertilizer to use for plants, they assume that the plants are healthy ones. The leaves of any plant are one of the most important parts. To explain their function in non-technical language, they serve as both the LUNGS and STOMACH of any plant. Often I have written and spoken about the value of magnesium as a much needed addition to the good plant foods you use in your garden. To prove it, you are advised to add some to each fertilizer application. Magnesium is one of the essential ingredients of chlorophyll, the green coloring matter of the leaf. With the assistance of sunlight it builds carbonaceous material from carbon dioxide which the leaf extracts from the air. Without this the sugar content of berries, tomatoes, currants, peaches, plums and many other fruits would be less. When used in the earth, its greatest value is in its ability to release other plant foods from the soil, making them available to the plant. Three of the most important elements essential to plant growth and health are oxygen, hydrogen and carbon. They are derived mainly from air and are component parts of starch and cellulose. To make them available and to put them to work, magnesium is needed.
In a recent article in the garden magazine HORTICULTURE, Paul W. Dempsey says, “We owe the beauty of this green world to magnesium. It is the key element in the molecule of chlorophyll, the green pigment in plants that traps the energy from the sun and makes plant life impossible. This pigment starts the chain of events that begins in the plant leaves and goes on up through animals and man. Magnesium also seems to be essential to the proper use of phosphorus by the plant. Where magnesium is deficient in a soil, there is a loss of green color in the lower leaves. The trouble gradually moves up to the stalk until all the leaves may be affected. The veins of the leaf remain green. The symptoms are described as chlorotic and the trouble is widespread in many sections of the country and on many different crops.”
Magnesium, like calcium and sulfur, is also a soil conditioner and a catalyst. The form in which magnesium is readily available here are EPSOM SALTS, CHALK, DOLOMITE and TALC. DOLOMITE is a granular magnesium carbonate of lime and, like chalk and talc, is decidedly non-acid. For ACID SOIL purposes and for plants which have a decided acid soil preference, use sulfate of magnesium (EPSOM SALTS). For neutral or non-acid soils, use DOLOMITE, CHALK or TALC. You can buy sulfate of magnesium from practically all good garden supply stores in small packages. Do not expect it to work miracles. It is applied as an addition to the properly blended fertilizer you are now using successfully in your garden. Recently, some remarkable results have been achieved by the addition of a heaped tablespoon of EPSOM SALTS to each gallon of spray material used on plant leaves. At first we thought the good results were caused by the fungicidal properties of the EPSOM SALTS, but recently we have found that the magnesium actually enters through the breathing pores of the leaves and is utilized instantly by the plant.
TIME TO USE
It does not seem to make much difference at what time the application is made. When new spring growth is being made seems to be the most logical period.
QUANTITY TO USE
Although I have made tests for more than 25 years, I do not seem to find a maximum or minimum amount to use. Some amounts for use that have proven satisfactory are:
LAWNS: One pound to each 50 square feet may be applied by hand or by spreader in a powdered form. If a liquid is easier to apply, mix one pound in two gallons of water and apply to 50 square feet with watering can.
SHRUBS, TREES, ROSES: One pound to 50 square feet. Scatter in powder form by hand evenly.
VEGETABLES & FRUITS: Apply one pound to each 50 square feet in April-May. Powder form in all-over application is simplest. For rows of vegetables or berries, it may be scattered by hand along side of rows of plants at the rate of one pound to 100 feet of row.