Why Is Fertilization Important?

Fertilization holds significant importance due to the following reasons:

• Nutrient enrichment: Trees require a consistent supply of nutrients for optimal growth. Fertilization ensures they receive any necessary elements lacking in the soil.
• Stress tolerance: Well-fertilized trees and shrubs are better equipped to withstand environmental stressors, including extreme weather conditions, pests, and diseases.
• Enhanced aesthetics: Fertilization promotes lush foliage, vibrant colors, and overall plant vigor, enhancing the beauty and aesthetic appeal of your landscape.

How can I tell if my trees need to be fertilized?

When your trees are lacking the nutrients they need. You’ll see several symptoms:

• Stunted growth– When a tree can’t get all the nutrients it needs, it will slow its growth to conserve energy.
• Thin or patchy foliage– If a tree is lacking nutrients, it will cut off resources to twigs and branches to conserve energy.
• Yellow leaves– Nutrient deficiency shows up in a tree’s leaves, making them yellow instead of healthy green.
• Dropped leaves– Your tree may drop leaves during the growing season when it doesn’t have enough nutrients and food energy to support them.
• Insects and diseases– A stressed tree has fewer natural defenses and is more susceptible to attacks from insect pests and diseases.

When should I fertilize my trees?

Spring and fall are the best times for tree fertilization.

Benefits of Spring Fertilization

When you fertilize your trees in spring, you’re giving them a hand after a long, cold winter. If you’ve had your trees pruned during winter or if they’ve suffered damage from winter storms, in spring they will start using their limited energy stores right away to seal off wounds. Spring fertilizing helps ensure your trees have enough nutrients for maximum leaf and flower growth. This means you’ll have vigorous trees that will give you summer shade and healthy crops of fruit.

Benefits of Fall Fertilization

After a long growing season, your trees start to wind down their activity in fall. Fertilizing your trees in fall will help them build up their energy stores to carry them through winter. (You won’t see any growth above ground during winter, but tree roots never sleep!).

The key to fertilization is timing

For example, adding nitrogen to your trees in winter will do nothing because, trees are dormant and not producing leaves, (this can also be a good time to trim & prune) and frozen ground means water-soluble fertilizer won’t reach tree roots. Also your trees need fertilizer at certain points in their annual growth cycles; at other times the fertilizer will be wasted. The best time to fertilize your trees is right when they need it.

Do newly planted trees and shrubs need fertilizer?

• In most landscapes, healthy trees and shrubs do not require fertilizers, especially when they reach their mature size.
• It is not recommended to fertilize at planting time. Research studies show most of a plant’s energy is directed to root growth during the establishment period. The application of nitrogen during this period seems to suppress root growth rather than enhance it.
• Trees and shrubs absorb nutrients applied to adjacent turfgrass.
• Fertilizer is not a remedy for landscape problems. Get your soil tested if you expect a nutrient deficiency. Most trees and shrubs prefer a soil pH (acidity level) of 5.5 - 7.0.
• Proper watering of newly planted trees and shrubs is the most important maintenance practice for establishing plants.
• Never fertilize a drought-stressed plant.

Fertilizer types

Fertilizers are identified by a guaranteed analysis (product label) such as 10-6-4 or 5-10-5. The three numbers represent the percentages by weight of nitrogen (N), phosphate (P2O5), and potash (K20), respectively, contained in the fertilizer.

Complete analysis granular fertilizer

A fertilizer with the three major plant nutrients, nitrogen, phosphorus, and potassium, is called a complete fertilizer. Commonly used complete fertilizers for trees and shrubs have a ratio of 3:1:1. We will select a fertilizer that supplies the nutrients your plant needs without over-supplying unnecessary nutrients. If your soil test indicates levels of phosphorus and potassium are adequate we will only need to apply nitrogen. However, it is often harder to find a nitrogen-only granular fertilizer. As an alternative, we might select a fertilizer with low amounts of phosphorus and potassium. Secondary nutrients like calcium, magnesium, and sulfur are sometimes included in fertilizers.

Slow-release nitrogen 

This form of nitrogen is supplied slowly over a relatively long period of time. It is usually more expensive than the more common water-soluble (fast release) nitrogen, but less likely to contribute to nutrient pollution of our water resources. Slow-release nitrogen is available at a uniform rate over the entire season. Many tree and shrub fertilizers are a combination of slow-release and quick-release sources of nitrogen.

Organic fertilizers and compost

These can be substituted for chemical fertilizers. Using shredded leaves (run collected leaves over with a lawnmower) to mulch trees and shrubs provides a slow release of nutrients as the leaves break down and eliminate the need to purchase mulch. Compost can also be used but don’t apply more than a 1-inch layer.

Tree Fertilization Methods

Our arborists will use one of two main application methods to fertilize your trees and shrubs; soil injection and direct injection. We will determine the best method of fertilization based on the condition of your trees.

Soil Injection

For this method, we use a special tool that injects fertilizer directly to the root system deep in the soil. This method works best when the soil is compacted, and it puts the nutrients deep enough to ensure that they reach the tree roots with little competition from the grass roots. We will assess your trees and shrubs to determine the right blend of macro and micro nutrients in the fertilizer.

Direct Injection

With this method, the fertilizer is injected directly into the vascular system of the tree. This is the most effective way to give your trees 100 percent of the necessary nutrients. We will use direct injection fertilization if your trees have a nutrient deficiency.