The three most important nutrients for plants are nitrogen, for green leaves; phosphorous, for healthy flowers and roots; and potash, for overall vigor and disease resistance. Bone meal is an excellent source of phosphorous and it is easy for gardeners to use. It is also the oldest form of phosphorous fertilizer. At one time farmers made their own bone meal by roasting the bones of livestock or soaking and fermenting them in water.
The effects phosphorous has on plants that can be easily observed by gardeners are in vitality, the time of blossoming and maturity. Flowers will produce more colorful blooms. A phosphorous deficiency may stunt growth and delay the emergence of new shoots and flower development.
Establishing healthy roots
Phosphorous is critical as a stimulus to root development. Roots branch out and root hairs form profusely in the vicinity of a source of phosphorous. Because of its effect on roots, phosphorous is a major factor in determining early growth of a plant and its vigor throughout the season. Applying bone meal when planting trees and shrubs, rose bushes and even dividing and transplanting perennials will help them establish a healthy root system faster.
The phosphorous in bone meal is released slowly as the soil water dissolves it so it can be taken up by the plant's roots. This provides a steady level of nutrients throughout the season. However, sufficient water is needed to make phosphorous available. Trees are usually planted at greater depths than most other plants and must receive adequate water - rain water alone will never supply sufficient moisture for them to develop a sound root structure. A consistent watering schedule is critical to establish new trees in their first season. Phosphorous is important in good root development and good root development is necessary to enable the plant to find and take up water containing phosphorous.
Bulbs and bone meal
For bulbs, phosphorous is the most important nutrient to ensure they flower and multiply annually. Feeding is especially beneficial for large bulbs such as tulips, hyacinths and daffodils. They should be fed bone meal twice a year. Once in the spring before the plants bloom and again in autumn after the first frost. If you only have time to feed once, it should be done in autumn.
Calcium is also a major nutrient needed for healthy and normal plant growth. It too plays a role in the development of a plants root system and the growing point or area of rapidly dividing cells at the tip of stems and branches. A deficiency of calcium can cause short, thick, bulbous roots or dieback of all the growing tips and tops.