This is an excerpt from the Book called “Trees Shrubs & Hedges FOR YOUR HOME”. Continue reading to learn more about Basics of Fertilization, thanks to the author.
Plants absorb most of the elements they require for healthy growth from the soil. Nitrogen (N) is essential for stem and leaf production, phosphorus (P) promotes root growth as well as the growth of flowers and fruits, and potassium (K) promotes flowering and fruit production. These three are the primary nutrients those needed in the largest amounts and used the fastest. Commercial fertilizers, whether organic or chemical, supply these nutrients and often secondary nutrients and trace elements as well, in combinations called “balanced fertilizers”.
Their packages list the proportions of the primary nutrients in terms of the N-P-K ration. An all-purpose balanced fertilizer might have a rating of 20-20-20, with all three elements in equal proportions of phosphate and potassium, such as 5-10-10. The rate at which a fertilizer releases its nutrients determines the way you use it. Slow-release fertilizers deliver their nutrients over several months and are applied annually. Manufactured slow-release balanced fertilizers deliver nutrients in 6, 8, or 12 months. Organic slow-release fertilizers include limestone, dolomite, superphosphate, and rock phosphate.
Where soil is infertile and when planting shrubs and small flowering trees and hedge plants, add to the hole (or bed) a combination of 8-month (spring planting) to 12-month (fall planting) slow-release fertilizer, as well as rock or superphosphate, which sustains root growth. After the second year, restore used up nutrients in midfall or late winter to early spring by applying a slow-release balanced fertilizer. This, in addition to an annual application of a rich organic mulch of composted leaves or manure, or a mixture of both, provides all the nutrients needed for healthy growth.
Quick-release fertilizers are used to give short-term boosts, if needed, during the growing season. Quick-release fertilizers include balanced “chemical” fertilizers and organic emulsions made from “natural” materials such as seaweed, fish, and manure. Manure steeped in water is known as “manure tea”. Most quick-release fertilizers are water soluble and can be sprayed onto leaves, a process known as foliar feeding.
Too much fertilizer of any type, but especially the chemical fertilizers, can burn tender roots and shoots, so never apply more than the amount suggested by the container label. With fertilizer, less is better than more. That’s because excess fertilizer can cause rapid weak growth that makes the plant vulnerable to wind damage, drought, temperature extremes, pests, and diseases. Besides, fertilizer runoff from lawns and gardens pollutes water systems.
Poor growth, discolored leaves, and failure to flower or fruit are signs of possible nutrient deficiencies, but they can be caused by other factors as well and are often hard to diagnose. Foliage plants with yellow leaves most likely need nitrogen, but the yellowed foliage of evergreens (yellow with dark veins in broad-leaved evergreens) suggests an iron deficiency. Poor flowering may be due to a lack of potassium and phosphorus or insufficient light.
A soil test can help identify the source of the problem. Check the pH, because pH affects the availability of nutrients and adjusting it may solve the problem without the need for fertilizer. If soil tests indicate a need for fertilizers, try applications of a quick-release form of a soluble fertilizer.
The three numbers on a fertilizer bag indicate the proportions of the three major nutrients, from left to right, nitrogen (N), phosphorus (P), and potassium (K). Flowering plants thrive with fertilizers that have a higher proportion of phosphate and potassium, like this fertilizer. Foliage plants do better with a higher proportion of nitrogen.
