Tree and Shrub: How Fertilizer Applications Are Done Correctly

Like all plants, tree and shrub growth depends on the presence of certain essential nutrients in the soil. Sometimes supplied by the decomposition of organic matter, these nutrients often deplete over time. Fertilizers provide the essential nutrients that trees and shrubs need for proper growth. Fertilizer application, however, can damage the plant and its environment if not managed properly. 

To ensure your trees and shrubs get their required nutrients without causing harm, it’s crucial to understand how fertilizer works. This includes knowing different types of fertilizer and how to apply them correctly.

What Separates a Tree from a Shrub?

Trees are tall, wooded plants that are supported by a single trunk. They typically have a distinct canopy of branches and leaves, which are both beautiful and beneficial. Providing oxygen, shade, and homes for many different species of animals, trees are an integral part of our planet’s ecosystem. While there are various types of trees, they each have a deep root system and protective bark. Similar to any plant, trees need sunlight, water and nutrients to grow.

Unlike trees, shrubs are much shorter plants with several stems growing from the ground. They are often used as decorative plants in gardens and landscaping and can provide privacy and protection from elements. Shrubs typically have a shallow root system and are not as sturdy as trees, making them more susceptible to damage. Requiring water, sunlight and nutrients, shrubs additionally require maintenance to stay full and healthy.

Fertilizer applications are one important way to maintain the health of both trees and shrubs. And while the process may seem insignificant, fertilization is vital to the overall health of our plants and planet. If you’re ready to provide your trees and shrubs with the proper nutrients, contact our experts at Exscape Designs today!

What Is the Best Fertilizer for Trees and Shrubs?

To ensure your trees and shrubs get the nutrients they need, it’s important to fertilize them regularly. But with many different fertilizers on the market, it can be tricky to know which are best for your plants.

Fertilizer labels provide a wealth of information to help you choose the right product. Providing nutrient ratios, such as N-P-K (nitrogen, phosphorus, potassium), is one way to help you select a fertilizer.

The numbers on the label represent the percentage of each nutrient in the product. Trees and shrubs typically need more nitrogen than phosphorus and potassium. General fertilizers for trees and shrubs include slow-release products with an N-P-K ratio of 3-1-2 or 3-1-1. Recycling organic materials, such as leaves and compost, is another way to fertilize your plants.

While fertilizing, you should only administer nutrients when deficiencies become apparent. Improper fertilization can lead to leaching, nutrient runoff and water pollution. To identify nutrient deficiencies in your tree or shrub, consider performing a soil test to assess what minerals are lacking.

Soil pH Analysis and Adjustment

Soil pH is an essential property to consider when cultivating your landscape. Most unaltered soils have a pH between 4.5 and 5.5, which is the optimal range for many plants. Other plants, however, prefer either a more acidic or alkaline soil. The ideal pH range for trees and shrubs, for example, is 5.5 to 6.8.

To test your soil’s pH, you will need a soil testing kit which can be purchased at most garden stores. After you have collected a soil sample, follow the provided instructions to determine the pH of your soil.

Once you’ve discovered the nutrients your soil lacks, you may add the specified elements to raise or lower the pH.

Essential Elements for Plant Growth

Trees and shrubs need a few key elements to grow properly, including oxygen, nitrogen, phosphorus and potassium. Playing a vital role in plant growth, these elements must be present in the right amounts for plants to survive.

Oxygen

Oxygen is essential for plant growth as it helps the plant photosynthesize. Like humans, oxygen helps plants convert sunlight and nutrients into energy. 

Nitrogen

Nitrogen is critical for plant growth as it helps improve leaf color and overall growth rate. Nitrogen deficiency results in stunted growth and yellow leaves. 

Phosphorus

Phosphorus helps with root development and overall growth. It is crucial to not over-fertilize with phosphorus as it can be invasive when carried by runoff. 

Potassium

Potassium is generally low in most soils and must be continually replenished to maintain healthy growth. Symptoms of potassium deficiency include dead areas around leaves, yellowing and slow growth.

While various symptoms can suggest a nutrient deficiency, applying fertilizer will not improve plant growth if another factor is present. Numerous causes including disease, over watering, pests and inefficient light can stunt plant growth. Fertilizing a plant that is otherwise unhealthy will not lead to recovery. In fact, applying fertilizer to a sick plant can do more harm than good.  If you find that your tree or shrub needs additional nutrients, be sure to calculate how much fertilizer you need.

Fertilizer Calculations

If your pH test indicates that your plant needs additional nutrients, it’s recommended that you calculate how much it needs. To calculate the amount of fertilizer to apply per 1000 sq ft, complete the following calculation:

Take the lbs. of nitrogen needed (as indicated by your soil test) multiplied by 100 percent. Divide this number by the percent of nitrogen in the fertilizer.

 lbs. N needed x 100%% N in fertilizer=area

This number will determine how much to apply to your landscape or garden once you’ve calculated the area.

How Much to Apply

The amount of fertilizer you need to maintain trees and shrubs is additionally determined by the size of the area. Areas, however, can differ in size and shape, making it difficult to determine how much fertilizer is necessary. To determine the amount of fertilizer you’ll need, you’ll need to complete simple calculations.

Rectangle or square

Multiply the length and width of the area to find the total square footage. 

length x width = area

Circle

Multiply 3.14, or π, by the radius, squared.

3.14 x r² = area

Half-circle

Find the area of a circle and divide it by two.

3.14 x r²2= area

Triangle

Multiply 1/2 by the length of the base by the height.

1/2  x  base x height = area

How To Correctly Apply Fertilizer

Once you’ve calculated how much fertilizer you should apply to your area, you are ready to start fertilizing!

Fertilizer should be spread evenly over the entire area to be treated. To evenly distribute your fertilizer, use a broadcast spreader or subsurface applications. If you are using a broadcast spreader, be sure to calibrate it regularly to ensure an even application. You may additionally want to consider the time of year and weather conditions when applying fertilizer. 

Avoid applying fertilizer in hot, dry weather, as this can cause the fertilizer to harm the plants. It is additionally important to avoid using fertilizer near water sources as it can run off and pollute the water.

The growth seasons for your plants will likely vary depending on the climate they are located in. Spring, late summer, and fall are generally the best times to fertilize your plants. This allows the plants time to absorb the nutrients before winter. If you fertilize in the spring, make sure to do so before new growth begins. Applying fertilizer to new growth can damage the plant.

Regular lawn maintenance is essential for any plant to keep it healthy and looking its best. At Exscape Designs, we understand that landscaping can be difficult and time-consuming. That is why we offer professional lawn care services to our clients. Our experienced landscapers will work diligently to ensure your lawn is always healthy and beautiful. Contact us today to learn more about our services.