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How, When and Why We Fertilize Trees | BC Tree Care

Updated: Jul 7, 2022

Trees are usually fertilized in the spring or fall seasons to prepare for winter, although it can be done any time of year.

At Horizon, we work seasonal tree fertilization into all our clients regular tree care schedules. Younger trees need to be fertilized more often than established ones so we tailor our planning to each client’s unique needs.

But why is it important? Find out below.

Why Fertilization Matters

Fertilization helps trees grow. That’s the basic answer.

The more advanced answer has to do with the periodic table.

Trees need appropriate amounts of nitrogen, phosphorus and potassium to grow strong and healthy. Too much or too little of any of these key nutrients will result in sickly trees, eventually leading to disease and tree death.

A tree’s main growth phase is during the spring and summer months, so applying fertilizer once in the spring is a great boost to that ideal growing season. Especially for young trees, where we really want to maximize their growth to reach their full height and make a client’s site look established and aesthetically pleasing quickly.

Fertilizer also helps a tree’s leaves look greener and more vibrant, adding appeal to our client’s sites.

Just as important is a second fertilization before winter. This is because trees still grow, but go into a rather dormant phase during cold winter months. The extra nutrients in the fertilizer helps them power through the winter until the next growing season.

Additionally, while the top of the tree may not be growing during winter, the root structure underground still is. These nutrients help that growth continue during winter.

Healthy, strong, well-fertilized trees can more easily repel pests and disease, two major sources of expensive tree repairs or replacements.

Our Fertilization Process

At Horizon, we create our own in-house specialized fertilizers. We use several types depending on the species of trees we’re caring for, as different species require different macro and micro-nutrient levels. All our fertilizers are water-soluable for 100% environmentally friendly application.

There are a few methods of fertilization we use:

1. Watering Bags

Also known as “gator bags,” these are the heavy poly bags you see tied around tree trunks, typically along sidewalks, walkways or entrances or any location where a tree is on its own.

These are a great option for large sites as they provide a steady slow-release of water and fertilizer, ensuring the tree gets all the fertilizer it needs for the season. They are also tidy looking and stay in place well.

Image Source: Pixabay

2. Deep Root Fertilization

This process involves injecting our water-soluble, liquid fertilizers at least 6” below the surface of the soil by the tree’s root system to deliver nutrients directly to the roots. This also ensures it stays in the soil for some time.

Deep root fertilization is the most common type we do because it’s the most efficient way to deliver vital nutrients directly to a tree’s root system. It also fertilizes the grass and other plants nearby which helps all your landscaping look its best.

This has the added benefit of aerating the soil at the same time, which is great for springtime fertilization and maintenance.

3. Surface Water

Surface, or broadcast fertilization, is like regular tree watering, spraying trees and soil with water via hose or irrigation systems, except that we add in our custom fertilizer blends, too.

Another option is dry pellet fertilization, where the nitrogen-rich fertilizer is compressed into dry pellets and spread over the soil surrounding trees. Watering it into the soil is necessary for the nutrients to soak in, and to prevent excessive concentrations of nitrogen to be released in one area, which could “overdose” a tree.

Our blends are appropriate for the species types they’re made for, but sometimes if we have concerns about a particular tree or job site, we’ll perform a soil sample first to determine if the tree is deficient in any essential nutrients (phosphorus, potassium or nitrogen). If it is, we will custom-engineer a suitable fertilizer to bring the tree’s levels back into a healthy range.

Main Benefits of Tree Fertilization

As we covered above, the main benefits of fertilization for trees are:

  • Nutrient boost to help young trees grow, and older trees stay healthy.

  • Can help trees repel pests and disease.

  • Reduces weed growth.

  • Improves water absorption of soil.

  • Boosts production of vibrant green, healthy leaves and foliage.

  • Helps trees stay strong during cold and dry winter months.

And most importantly…

  • Fertilized, well-cared-for trees reduce long-term costs by keeping existing trees healthy.

Call Us for a Custom Quote Today

Let us take care of your trees to keep your facility looking fresh and welcoming to your tenants and customers year-round.

Contact Russ Thomson at 604-807-0500 or for a custom quote tailored to your specific needs.

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