Liquid Feeds for Garden Plants
are becoming more popular for supplying nutrients for plants, particularly those grown under glass.
The modern factory-made, marketed as concentrated solutions or as solid mixtures for making into concentrated solutions, are more consistent in composition than the foul-smelling concoctions made by suspending sacks of animal droppings or soot in tubs of water. The main constituents of most liquid are potassium nitrate, mono-ammonium phosphate, and ammonium nitrate or urea. These are mixed in various proportions to give a wide range of different analyses to suit the needs of most crops and soils. Liquid manure derived from seaweed and humus extracts supplies useful amounts of trace elements as well.
Liquid feeds are not necessarily better than solid feeds. A gardener who is skilful in using solid fertilizers will no doubt obtain results just as good as those he would get with liquid feeds, and vice-versa. But liquids are popular because of the ease and speed with which nutrients can be applied in balanced form, to meet the changing needs of plants at different stages of growth and weather conditions. They also save time in feeding and watering since these are done in one operation. They sink evenly into the soil, where they are quickly and naturally absorbed by the roots.
Liquid feeding is more expensive than solid feeding. Concentrates sold in bottles have to be diluted with water according to the maker’s instructions, which should be carefully adhered to. If a dilution of l in 200 is recommended, measure l fluid oz. (2 standard tablespoonfuls) to 1-1/4 gal. water. One in 500 is equivalent to about l fluid oz. to about 3 gal. water. Water the diluted solution on to the soil by means of a watering-can and rose.
If a big area is to be covered, buy a diluter into which the stock solution from the bottle is poured and from which the feed is picked up by a hose when connected to a tap.
Plants can absorb nutrients through their leaves when they are sprayed with dilute solutions of fertilizers. Radioactive tests show that micro-nutrients applied in this way can be in the sap stream within one hour after application. Thus, the long journey from the root to the leaf is avoided and nutrient deficiences may be corrected rapidly.
It is difficult to say whether leaf sprays can be used to advantage for feeding vegetable crops, but they are preferable to soil dressings for plants with poor or diseased root systems. They are useful for giving a boost to growth during dry weather when there is little soil water in which to dissolve fertilizers. Deficiencies of manganese, iron and other nutrients in plants growing in chalky and other alkaline soils can be quickly corrected by means of suitable substances applied as leaf sprays.
To strengthen and increase leaf growth, a spray containing urea at the rate of 1 oz. per 2 gal. water will be sufficient to cover 25 to 30 sq. ft. of soil fully covered with foliage. Potassium nitrate, when applied at the same rate, will help to harden soft sappy tissues without checking growth.
Buy one of the proprietary products specially designed for foliar feeding. While many of these are based on highly soluble inorganic fertilizers, all-organic seaweed preparations are also available.
Apply the sprays when the plants have developed enough leaves to ensure a reasonable amount of leaf absorption, and then spray once a week or according to the maker’s instructions.
Use a fine mist-like spray to cover both sides of the leaves. Keep the spray moving the whole time to ensure that the plants receive a reasonable and equal amount of liquid. Always add a wetting agent such as Agral (at rates according to the manufacturer’s instructions) when spraying plants with shiny leaves, other-wise the food spray will run off the leaves without being absorbed.