How to fertilize a Rose bush
Roses need to be kept regularly fed, but like human beings and animals they do not want to be overfed, and certainly not with the wrong foods. What they like most of all is a well-planned diet given to them at the appropriate times of the season.
In addition roses are thirsty plants and need copious quantities of water. It is important to water whenever there is a dry spell, no matter how early in the season it might be, and not just during a heat wave, when their leaves are drooping, because by then it might be too late. Without a good supply of water roses are unable to manufacture their food, absorb the raw materials for this process from the soil and maintain the level of sap so that it can transport them to the places in the tissues, where they are converted.
Some gardeners think that organic or natural fertilizers are more beneficial to plants than inorganic or chemical ones. This is not completely true, because unlike animals, plants can only absorb plant food as simple chemical compounds. These are provided immediately by inorganic fertilizers, whereas the beneficial elements in organic fertilizers, which are complex substances cannot be taken up by the roots until they have been broken down into simple chemicals by the action of soil bacteria, which might take some weeks. Both types have their place in plant nutrition, because the organic fertilizers supply vital foods regularly over a long period and help to ensure their continuous presence in the soil, whereas the chemical fertilizers make supplies available to meet emergencies and special seasonal needs. Any nutritional advantages of organic fertilizers lie firstly in their soil-conditioning qualities as humus makers and the fact that they are sources of unspecified quantities of trace elements, required by plants in minute quantities. If inorganic fertilizers are used alone these have to be added.
Roses, like other plants, manufacture their own supplies of starches and sugar from carbon dioxide from the air and water from the earth through the agencies of the green coloring matter in the plants (chlorophyll) and sunlight. This is carried out in the vast majority of plants in the leaves. A good supply of moisture is necessary for this operation to be successful.
Apart from starch, however, roses need other vital substances if they are to flourish. Among these are proteins, chlorophyll, enzymes, nucleic acids and all sorts of other complicated compounds. These are all built up in the tissues from various elements that for good health, these must be continuously available in the earth. To be sure of this, it is necessary to feed.
Plant Foods These are divided into two groups, the major nutrient elements, and the minor nutrient elements or trace elements.
Nitrogen is a constituent of many of the most vital substances used by a rose. It is, therefore, essential for the maintenance of good health, but too much is bad, because nitrogen encourages leaf-growth and if given lavishly, produces lush growth, which is often weak and falls an easy prey to disease and frost. Nitrogen compounds should not, therefore, be put down late in the season. In addition, excess nitrogen encourages roses to grow abundant foliage at the expense of flowers. Plants deficient in nitrogen usually look feeble and have yellowish leaves.
Phosphorus (Phosphate) is also a vital constituent of rose foods. It is beneficial by encouraging earlier growth, the ripening of the wood, hardening plants to resist winter conditions and improving the root systems. Its shortage is manifested by stunted growth and leaves that are tinged red.
Potassium (Potash) plays a leading part in plant growth. Without it, stems are brittle and roses are very vulnerable to disease and frost. Also parts of the plant, where winter food supplies are stored, such as roots and seeds, are poorly developed. Roses deficient in this element usually have leaves that are yellow at their tips and round their edges.
Calcium not only helps to condition soil and keep it from becoming excessively acid, but is also important to roses because it is essential to the efficient working of the tissue cells. It is not very frequently deficient, but when it is, it is signified by malformation of the young leaves as they appear.
Magnesium is an important component of chlorophyll, which is essential to the food manufacturing process of roses. A severe shortage can be noted by the yellowing of first the older leaves and then the young ones.
Minor Nutrient or Trace Elements. Iron and Manganese are two of the most important trace elements because they are closely associated with the production of chlorophyll. Where they are deficient the younger leaves yellow, still leaving their veins green.
Other trace elements are copper, boron, molybdenum, and zinc.
A Feeding Program A program for feeding roses begins late in the winter after supplies of nutriments have become diminished. The first thing to do, preferably in early spring, provided the snows have gone, is to lay down foundations by distributing an organic fertilizer, which will break down over the ensuing months into simple chemical compounds and ensure that there is a
basic supply that can be steadily absorbed by the plant. If it can be obtained, the substance to distribute is bonemeal at the rate of two handfuls per square yard.
Fertilizer is next applied in the spring, not earlier than April. This time it is a chemical fertilizer, which supplements the elements provided by the organic fertilizer, particularly when heavy rain has washed abnormally large quantities of a particular element away, or rapid growth, due to favorable weather conditions, has suddenly increased demand and soon. Generally, it is more satisfactory to put down a proprietary, ready-mixed rose fertilizer, of which there are several on the market. It is important to use one that is blended for roses and not a general fertilizer intended for vegetables, because sometimes the latter contains muriate of potash which is deadly to roses. Such rose fertilizer is distributed in accordance with the manufacturer’s instructions. Usually these mixtures contain the trace elements that are needed by roses.
Although it is a lot more trouble, gardeners may mix their own fertilizer for roses. A recommended mixture is: Nitrate of potash 3 parts, Sulfate of ammonia 1 1/2 parts, Superphosphate of lime 8 parts, Sulfate of potash 4 parts, Sulfate of magnesium 1 part, Sulfate of iron 1/4 part.
This is distributed at the rate 2 oz. (about a handful) per sq. yd. once in April and again in May. Twenty pounds of this mixture is sufficient for 200 roses during the season.
It is important that no chemical fertilizer is applied after the end of July, otherwise lush growth might be produced, which will not withstand the winter.
Foliar Feeding This takes advantage of the fact that leaves absorb nutrients from liquids sprayed on them. It is not a substitute for the regular feeding program, but something that can meet an emergency. There are several good foliar feeds on the market. They are best applied in the early morning or in the evening, but never in hot sun.