What Does Phosphorus Do for Plants?

Phosphorus is vital to the growth and health of plants. It assists in converting the sun’s energy and other chemicals, such as nitrogen, into usable food for plants. A phosphorus deficiency will lead to stunted, sickly looking plants that produce a lower quality fruit or flower.


Phosphorus must be mixed with water for plants to be able to absorb it from the soil. Phosphorus is broken down and combined with other chemicals before the plant is able to absorb it. Phosphorus then combines with other chemicals to form ions. Phosphorus (P) binds with hydrogen (H) and oxygen (O) to create a soil solution. Once soil solutions are formed, plants can absorb the phosphorus through their root system.


Phosphorus is one of the three main nutrients plants require to thrive: phosphorus (P), nitrogen (N) and potassium (K) . It functions as one of the major players in the process of photosynthesis, nutrient transport, and energy transfer. Phosphorus also effects the plant’s structure at a cellular level. A plant with the proper amount of phosphorus available to it will grow more vigorously and mature earlier than plants with inadequate phosphorus. A plant with phosphors deficiency will exhibit stunted growth, lack of fruit or flowers, wilting and leaves may be greener or have a purple cast to them due to the photosynthetic process being affected.
Mixing a phosphorus rich fertilizer with soil when planting will help the plant establish a stable root system and have a strong first growing season. It’s recommended to include sand in the planting mix to held with drainage if planting in a poorly drained area.


Fertilizers can be added to the soil to increase the phosphorus available to plants. Once a phosphorus deficiency is detected, test the acidity of the soil to discover the best type of phosphorus to apply and whether or not a lime treatment should also be administered. The soil acidity will determine whether organic or inorganic fertilizer should be used. Organic fertilizer works fastest and gives the best result when the soil is warm and well drained. Inorganic fertilizer is affected more by the acidity of the soil versus the temperature or drainage. Acidic soil below pH level of 5, or alkaline soil with a pH level higher than 7.3 both have negative affects on phosphorus. The phosphorus becomes fixed in compounds plants are unable to utilize. A lime treatment will help acidic soil and rock sulfur, sawdust, composted leaves and peat moss will serve to help make soil less alkaline.
The ideal soil pH for either organic or inorganic phosphorus fertilizer is between 6 and 7. It is recommend to perform regular pH testing on the soil to regulate applications and pH levels.


Soil naturally contains phosphorus, but due to today’s high-yielding crops and landscaping plants, more phosphorus is required to attain the desired effect, so adding phosphorus becomes necessary.
There are two types of phosphorus available: organic and inorganic. Organic phosphorus is commonly found in animal manure, plant residue and hummus.
Inorganic phosphorus is commonly used by farmers in the United States. The amount of phosphorus is more easily regulated and easier to administer to plants. Commercial fertilizer is created from processing phosphate rock. The phosphorus is only available to plants when the rock has been processed and turned into fertilizer. Espoma, a popular fertilizer manufacturer for landscaping plants, offers Rock Phosphate fortified with necessary minor chemicals.


Phosphorus is necessary for the growth of plants and is naturally found in soil. But the use of phosphorus-containing fertilizer, both organic and inorganic, should be closely monitored. Phosphorus can bind with surface soil into solids and facilitate runoff and erosion. When vast amounts of phosphorus are introduced into waterways, especially ponds and lakes, it produces a massive growth in algae. The algae dies and decays in the water, robbing upper level plant and animal life of much needed oxygen.