Osmocote for Planting Trees

Slow-Release Fertilizers

• Plants can take in the nutrients they need from both organic, or natural, and inorganic fertilizers. Inorganic fertilizers dissolve in water quickly, which makes them available to plants almost immediately. Organic fertilizers “hold” their nutrients in natural chemical compounds, and it takes time as well as moisture, heat and soil microorganisms to break those compounds down into their basic elements. Inorganic fertilizers coated with resins or other slowly degradable substance act much like organic varieties as a result and are called slow-release fertilizers.

Osmocote Choices

• Several different Osmocote brand slow-release inorganic fertilizer formulations are available for backyard gardeners, and all can be used when planting trees. The first and original is Osmocote Outdoor & Indoor Smart-Release Plant Food, which has a nitrogen-phosphorous-potassium analysis of 19-6-12, a popular formula for landscape trees and shrubs. Osmocote Flower & Vegetable Smart-Release Plant Food is 14-14-14, offering equal amounts of the three major fertilizer nutrients, a useful product when soil phosphorus levels are low. Osmocote Plus Multi-Purpose Plant Food is 15-9-12 and also contains nine other essential plant nutrients.

Need for Fertilizer

• Before buying or applying fertilizer, know the basic nutritional composition of your soil. It’s the only way to make an informed fertilizer decision when planting trees and shrubs. Take soil samples for a comprehensive soil test to find out what nutrients your soil contains and in what quantities. Your county extension office can provide you with a soil test kit and instructions. The soil analysis will also include suggestions about how to amend your soil.

Planting Trees with Osmocote

• You can safely incorporate Osmocote and other slow-release fertilizers into the backfill soil – the soil you remove from the planting hole to make room for the root ball – which is not true of quick-release fertilizers. Apply up to 0.2 pounds of slow-release nitrogen per 100 square feet of planting area per year for newly planted trees, according to University of Minnesota Extension. That translates into 1 pound of Osmocote 19-6-12 or 1.4 pounds of Osmocote 14-14-14. Following the same basic calculation, you would use 1.33 pounds of Osmocote 15-9-12 per year. Divide the annual amount, using half at planting and the rest later in the year.

Planting with Osmocote Alternatives

• Other brand-name slow-release inorganic fertilizers work much like Osmocote, in addition to commercial slow-release organic fertilizers. But you can get the same benefits from natural organic fertilizers that can be bought in bulk at some garden centers and feed stores. Most of these natural substances, such as alfalfa pellets and fishmeal, take from one to four months to release their nutrients and can be safely incorporated into the backfill. However, some – particularly blood meal, an excellent source of nitrogen – can burn tender roots if over applied.