When trees grow out in their natural range – whether it’s the rich loam of a forest or the sandy terrain of a beach – they typically thrive on their own without the help of people adding any fertilizers. Of course, the conditions in a home gardener’s back yard rarely mimics a tree’s optimal environment, so in some cases it’s necessary to help plants along by providing additional nutrients.
Consider adding a hose-end fertilizer applicator to your tools, especially for use with plants in containers or those planted in beds with loose soil.
Photo Credit: ©2002 Dolezal Publishing/John M. Rickard
Choose fertilizers by their nutritional analysis and acid content, matching them to your plants’ needs. Apply fertilizers at the recommended time and interval for the species, and always carefully read and follow label instructions.
Photo Credit: ©2002 Dolezal Publishing/John M. Rickard
Liquid and water-soluble fertilizer: Apply liquid and water-soluble fertilizers to the soil around the plant’s drip line (an imaginary circle on the ground under the outermost foliage).
Photo Credit: ©2002 Dolezal Publishing/John M. Rickard
Dry fertilizers: Apply dry, granular and synthetic fertilizers by sprinkling them onto the soil around the plant, then working them into the soil with a hand fork or claw. Water after application.
Photo Credit: ©2002 Dolezal Publishing/John M. Rickard
Manure: Apply natural manure and inorganic mineral fertilizers by spreading them across the soil surface around the plant. Work them into the surface with a rake, fork or claw. Water after application.
Photo Credit: ©2002 Dolezal Publishing/John M. Rickard
Organic compost: Apply organic compost to the soil in a 2- to 3-inch layer, avoiding contact with shrub stems or tree trunks. Water after application.
Photo Credit: ©2002 Dolezal Publishing/John M. Rickard
Foliar sprays: Apply foliar fertilizers using a hose-end sprayer set to the proper package-recommended application rate. Choose an early time on a calm, warm day to apply, in order to allow foliage to dry before evening.
Photo Credit: ©2002 Dolezal Publishing/John M. Rickard
Of course, the only time you really need to fertilize a tree is when you have to correct a nutritional deficit. You can spot most deficiencies by unusual coloration in a tree’s leaves. Yellow leaves on a tree that normally has green foliage is often a sign of either a nitrogen or iron deficiency. With a nitrogen shortage, the entire leaf turns yellow and may drop off, while a plant with an iron deficiency will have leaves with green veins, even as the rest of the leaf turns yellow. Leaves also may be smaller compared with those of other trees of the same species growing in your garden. You might also note that new twig growth may be shorter than in past years.
If you notice any of these symptoms, first rule out any disease or pest as the cause. If you think there’s a nutritional deficiency, perform a soil test. If the test results indicate a shortage of nutrients, follow its recommendations regarding the amount and type of fertilizer to use. (Generally, flower and fruit trees need additional potassium and phosphorus, while most others require nitrogen. An iron deficiency is usually treated with chelated iron.)
On loose, sandy soils, broadcast the fertilizer over an area twice the diameter of the tree’s canopy. If your soil is clayey or compacted, you can bore holes in the soil around the tree’s drip line (the area beneath the outer edge of the tree’s canopy) and fill the holes with a slow-release fertilizer, which feeds plant roots at a prescribed rate over a period of time.
Shrubs, especially flowering species, may need to be fed more often than trees. Use a light application of all-purpose fertilizer in spring and again in summer. Feed more frequently if there’s a nutritional deficiency, as indicated by unusual leaf coloration and confirmed by a soil test.
Fertilizers are available in natural, organic, inorganic, synthetic, liquid, dry and water-soluble forms. The composition analysis is on the package as a trio of numbers such as 10–10–10 that indicates the relative percentage by weight of nitrogen, phosphorus and potassium (or N-P-K) in the fertilizer. Nitrogen fuels foliage development, while phosphorus and potassium help nutrient transport among roots, stems and leaves. They also promote general vigor. For most tree and shrub applications, a complete, balanced fertilizer is best. To apply various fertilizers, choose from the options shown in the following pictures and described in their captions.
Just remember, whenever you apply fertilizers, keep in mind this simple message: When in doubt, less is better than more. You can always add fertilizer at a later date, but it’s difficult to undo the damage done by too heavy an application of fast-acting chemicals. Also be sure to water well after any fertilizer application to avoid burning your plants. When fertilized right, your trees and shrubs will live long, healthy lives – even in the unnatural environments of the back yard.
