Granular Vs. Liquid Fertilizers for Plants

Granular

• Granular fertilizers are composed of very small, coated dry pellets. The granules contain a prescribed blend of the three primary nutrients -- nitrogen, phosphorus and potassium -- and often additional nutritional additives. The nutrients inside the granules are slowly activated when they make contact with soil and water and are released into the soil to feed the plants. Granular fertilizers are used for indoor and outdoor plants and are typically sown into the soil when the plants are planted. However, granular fertilizers can also be applied on the top of the soil after plants are established.

Liquid

• Liquid fertilizers are used for indoor and outdoor plants and come in powder or liquid concentrate formulations that are added to water to apply to the soil and plants. Liquid fertilizers are applied to indoor plants using a watering can, while outdoor plants receive liquid fertilizers via a garden hose attachment that dilutes the concentrate to the appropriate level. The primary benefit of liquid fertilizers is that they provide plants with a quick energy boost to spark leaf and floral production.

Similarities

• Granular and liquid fertilizers are both used to stimulate healthy growth and development of plants. They can be purchased in different formulations to supplement the nutrients that plants receive from the soil. For example, a 20-20-20 liquid or granular fertilizer has an equal percentage of nitrogen, phosphorus and potassium, in that order. If the first, second or third number is higher, that means the formulation has a higher concentration of that respective nutrient. Granular and commercial liquid fertilizers are categorized as inorganic because they do not contain 100 percent organic materials such as wood or manure, which naturally decompose into the soil. The exceptions are products such as fish emulsion or homemade compost teas. Commercial fertilizers include some trace elements, such as the coating of granules and the chemicals used in liquids, that can remain in the soil for a long time before they breakdown and decompose. And unlike organic fertilizers, neither liquids nor granular fertilizers produce microorganisms or interact with worms, as happens with organic compost materials.

Differences

• Liquid fertilizers will drain and leach, losing their adherence to roots and the soil and not providing a stable and sustainable source of fertilization. Most liquids will lose their efficacy with one to two weeks and will need to be reapplied. However, because of the slow, time-release properties of granular fertilizers, they can remain effective for anywhere from one to nine months, based on the quality of the fertilizer, the frequency of watering and how quickly and eagerly the plant absorbs the nutrients.