The Homeowner’s Guide to Tree Fertilization In Denver

Denver is a desert climate, which means your trees are starving for nutrients!

When people first move to Denver, there are usually a few early observations:

  • “Is it normal to feel like you’re going to die walking up a flight of stairs or is that just the altitude?”
  • “I can finally tell which direction I’m facing because of the mountains!”
  • “There is no humidity in Colorado.”
  • “My hands, my face, my hair, my eyes, everything feels dry up here!”

That last observation is courtesy of Denver’s desert climate. Wait- Denver is in a desert? Technically, yes; Denver is classified as a high-altitude desert, which is surprising for many visitors and newcomers. No, there’s no sand or many cacti, but there’s no doubt: Denver is an arid climate.

Growing anything green on your property takes more work in the Mile High City than most other places across our great nation. Lawncare companies often talk about how difficult it is to maintain green lawns during July and August. When the temperatures hit triple digits after Independence Day, that’s when the lawns start to turn brown. What’s harder to detect is how hard the extreme temperatures and desert conditions are for trees and shrubs to thrive across Denver.

Think about how much more water your body needs living in Denver compared to living at lower altitude or sea level. The higher altitude demands a higher moisture level for all living things, including humans and trees. As the summer months warm up, your trees and shrubs need added nutrition when the rains dissipate before the fall arrives.

That’s where tree fertilization is key to your trees’ long-term health. Could your trees be ‘just fine’ if you don’t provide any supplemental nutrients by way of tree fertilization? Maybe, but we guarantee your trees will be more susceptible to disease and insect infestations as well as potential breakage and stunted growth without tree fertilization. The question is how long you want your trees to live and whether you’re prepared to pay extra for removing and replacing trees at a more frequent rate. Tree fertilization reminds us of the saying from the old Fram oil filter commercial: “You can pay me now, or you can pay me later.” The same is true with trees in Denver: do you want to pay several hundred dollars for a new tree every five to seven years, or would you rather pay for tree fertilization now at a fraction of the cost?

Our Fielding Tree & Shrub Care team loves taking care of healthy, happy trees. That’s why we’ve created this “Homeowner’s Guide to Tree Fertilization In Denver” resource. This step-by-step guide will help you know what to look for from your trees, how to know when and why they’re undernourished, and what tree fertilization treatments we recommend to keep your trees and you safe and healthy.

How to Determine If Your Tree Needs Fertilization

Trees derive all of their nutrition through water, sun, or the soil. As you probably know and love, Denver has more than enough sunshine with over 300 days of abundant sunshine every year. Where Denver trees are lacking is water and soil nutrients.

Much of Denver’s native soil is heavy with clay, which makes root penetration and water absorption beneath the surface a challenge for trees. This elevated (pun intended) amount of clay in our soil makes even planting trees difficult, let alone root growth for maturing trees. That’s where we focus on the term “tilth”.

According to Colorado State University Horticultural Extension, tilth refers to “the physical properties of soil which make it able to support plant growth.” (CSU Extension) Tilth is the texture, mixture, and balance of a soil’s quality, and in the case of Denver, much of the top soil found in the metro area is harder, separated, and unbalanced because of the amount of clay and sand found in our soil.

What do we know about clay’s horticultural properties? Clay is one of the more nutrient-deficient soil composites found anywhere around the world. There’s a reason why ancient societies and even today’s masons and pottery experts use clay as their primary material. Clay is extremely difficult to break up, which is what tree roots need to thrive in growing. That’s why diluting the proportion of clay before planting a new tree is one of the best practices to ensure a healthier future.

It’s likely your property has several trees already established and starving for better nutrition. The bad news is there isn’t an obvious, big flashing sign at each tree that flashes “Feed me!” when it’s needing more nutrition. However, there are four key signs your tree needs tree fertilization:


  • Slow growth: If your tree is not growing at the expected rate of growth, there’s a good chance the soil quality is stunting its growth. Adding tree fertilizer is a great way to keep your tree growing at a healthy rate.


  • Discolored leaves: Premature dieback or out-of-season leaf discoloration or canopy loss could be a sign of infestation or disease, but there’s a good chance it may be your tree isn’t getting a healthy diet of vitamins from the sun, soil, or water.
  • New plant or recent transplant: As a rule of thumb, all new trees and recently transplanted trees are low on nutrients. It’s similar to your kids needing their vitamins as they grow to stay healthy and strong. Let’s give the same TLC to your young growing trees.
  • Smaller leaves and shoots: Smaller leaves or stunted shoots are often a sign of nutrient deficiency for trees. If your tree didn’t quite produce the volume and size of leaves as it did last year, it may need a tree fertilizer injected to ‘pump up’ the production.



After working with trees in the Denver area for almost 20 years, we’re confident saying virtually all trees in Denver need some form of fertilization. So, how do you prepare your trees and the rest of your property for the proper approach to tree fertilization?

Preparing Your Property for Tree Fertilization

We highly recommend doing spring and fall applications of tree fertilizer. The first step is a complimentary on-site inspection by one of our certified arborists to take a look at your tree, give it a good checkup, and prescribe the right treatment for optimal health.

We recommend fertilizing immediately after trimming your trees. The shock of trimming limbs and branches can be significant to a tree’s vascular system. Giving your tree a haircut and a soil injection of tree fertilizer is a great one-two punch for keeping your tree healthy and happy.

Before you start fertilizing your trees, it’s important to clear away any dead or broken tree branches or ground shoots. By clearing the ground around the base of your tree, it will give our certified arborist plenty of space to properly implant soil injections.

Tree Fertilization - Fielding Tree and Shrub Care arborist DenverTree Fertilization Treatments We Recommend for Trees In Denver

In case there’s any uncertainty, we love caring for trees like they’re our own. This means we want to use only the best and safest tree fertilization options for trees in the Denver metro area. The last thing we want is for anyone, especially your children or fur babies, to be at risk from potentially dangerous-to-them tree fertilizers.

That’s why we need to identify the species of tree that may need fertilization so we can choose the right fertilizer for what your tree needs. This process can be part of our on-site complimentary inspection or by you sending us a few pictures of your tree for our certified arborists to review. Once we know what species of tree you have, we can select the best treatment plan for keeping your tree well-fed and well-rounded into the future.

We recommend a number of tree fertilization treatment options, but as a policy, we do not use airborne tree fertilizers. We feel there’s unnecessary risk associated with airborne tree fertilizer as well as not being confident the tree actually receives the most effective amount of dosage. This is why we prefer soil-injected tree fertilizers.

Here are a few tree fertilizer treatments we use and recommend applying under the supervision of trained arborists:

  • Cambistat(TM) is the leading product for regulating tree growth and strengthening root systems. We use Cambistat as a soil injection application to help trees maintain their growth rate while creating a powerful, healthy root system. Our team takes every precaution necessary to ensure any Cambistat applications are done in the specific prescribed manner.
  • We also use some forms of Biochar to help promote healthier soil around the base of trees, especially young trees or trees in the transplanting process. In essence, the biochar helps further break down hardened soil for your tree’s root system to further spread. Think of biochar as a type of permanent compost made from organic matter that allows essential microbes to thrive in the soil and feed your tree.

While these are just a few of the organic and synthetic tree fertilizers we may use, our approach is valuing safety and health for everyone involved. Our Fielding Tree and Shrub Care team will not use any tree fertilizer application that has a questionable background or is known to cause health complications.

Start Feeding Your Trees the Nutrients They Need Through Tree Fertilization

Whether your trees are sending out shoots for spring or dropping leaves for the fall, they’re ready for a healthy heaping of vitamins. The first step is connecting with our team of certified arborists to schedule your complimentary on-site inspection. One of our arborists can walk your property with you, inspect your trees, answer questions, and provide the answers and direction you need to keep your trees healthy and happy for years to come. Happy trees equal a happy Fielding team, which is why we’re Denver’s favorite arborist because we will treat you and your trees like we would want to be treated.