Organic Apple Tree Fertilizer

A good system of fertilization will maximize fruit production.

Organic fertilizers come from natural, as opposed to man-made or chemical, sources. Fertilizing apple and other fruit trees is imperative for proper development and may even help to stave off diseases and pests by promoting healthy, naturally-resistant trees.

Animal Manure

Fertilize with manure when you plant your apple trees.

Animal manure amends soil with all three nutrients vital to growth and fruit production: nitrogen, phosphorous, and potassium. It can be combined with straw or hay and mixed into the soil when trees are planted. It should not be used near harvest or as a soil-topping fertilizer because of the danger of contamination between fruit and fecal matter.

Compost

Fertilizing with compost may help suppress diseases.

Compost is an organic fertilizer made from decayed plant matter, and, like manure, is rich in nitrogen, phosphorous, and potassium. Compost can be applied on top of the soil, and, according David Granatstein, coordinator of the Washington State Center for Sustaining Agriculture and Natural Resources, it is an effective disease-suppressant.

Unless you are certain of the make-up of your compost, this fertilizer should not be spread within 90 days of harvest, because some composts do contain animal manure.

Nitrogen

Only fertilize with additional nitrogen if trees show signs of deficiency.

Nitrogen is the only of the three fertilizer nutrients that is fast-moving. Phosphorous and potassium remain in the soil where they are placed, making soil-top applications fairly ineffective. Nitrogen, however, can be applied to the topsoil and will rapidly spread downwards to the roots where it is needed. Be careful, however, not to over-fertilize. Apple trees store nitrogen from season to season, and too much of this nutrient will encourage sprouting, which does not harm the tree, but lessens fruit production.

When to Fertilize

Fertilize your apple trees every spring.

Fertilize when trees are first planted, and again each spring when new growth begins to appear on the trees. 5 pounds of compost for each year of a tree's age can be spread at the base of the tree and covered with mulch or straw. During fruiting season, trees only need to be fertilized if they show signs of deficiency.

References

• "Plant Talk: Fertilizing Fruit Trees" Colorado State University Extension Office
• "Organic Apple Tree Fertilizer" Garden Guides
• "Organic and Low-Spray Apple Production" National Sustainable Agriculture Information Service