Tree fertilization is a bit of a complex subject for many people. It’s true that there are forests that don’t get any kind of care and the trees still grow big and strong. However, many of those trees fall before their time.
If you have a tree in your yard or at your place of business, you need to be careful about their health and do everything that you can to keep them standing strong and tall. That includes getting regular tree care and fertilizing your trees whenever possible.
Why You Should Fertilize Your Trees

Oregon State University
- Increases resistance to diseases and infestations
- Can help with deficiencies
- Some trees will not respond
Fertilizing your trees is extremely important, according to the Morton Arboretum. They suggest fertilizing trees will help to ward off diseases and infestations. Many of these problems will start near the root system, so if they cannot get there, they will move onto another tree. Even if there is a disease present, the nutrients and support of the fertilizer can help your tree to fight them and get better again.
If your soil has deficiencies (especially if you plant a tree that isn’t native to our area), you may be able to supplement with fertilizer. This is an exacting science, so you will have to do some research, but it is possible.
However, it is also important to note that not all trees respond to fertilization, especially new trees and those that have been injured.
When Should You Fertilize Your Trees?

- Depends on the type of tree
- May also depend on the type of fertilizer used
- As the tree matures, there are different needs
When you are looking to fertilize your trees, the next question becomes “when” you should do it. As mentioned above, it is generally best not to fertilize newly planted trees. If you have a tree that grows quickly, fertilizer may be a good option to provide added nutrients that the earth cannot provide (think of the tree zapping nutrients like a teenage boy raids kitchen cabinets). More mature trees may need fertilizer as they may not be able to pull from the earth around them.
As for the “when” during a time of year, that is a little tricky. According to ThoughtCo, “Ideally, growing trees should be fertilized throughout the year but a bit differently as trees age. A tree needs larger amounts of nitrogen (N) based fertilizer during the growing season. Nitrogen-based solutions should be applied during the early spring and summer months.”
Do All Trees Need To Be Fertilized?

- Most native species trees do not need to be fertilized
- Some trees need varying amounts of tree fertilizer
- Certain species respond better to fertilization
Fertilization depends on the type of tree, the place it is planted, and even the weather. However, not all trees need to be fertilized. It will all depend on your individual tree. The best thing you can do is get a professional assessment or at least compare your individual tree to a healthy tree.
Having trouble determining whether or not your tree needs to be fertilized? HGTV has you covered: “Compare trees to others of the same kind: Look at leaf size and color, and the length of new twig growth. Small, pale leaves and stunted growth may signal fertilizer need, but first rule out disease, insects, physical damage, and environmental stress such as flooding or drought. To determine which supplemental nutrients your tree needs, send a soil sample to a testing lab. Find a lab near you by checking in your telephone directory, or by calling your local cooperative extension office.”
When you do fertilize, remember to look for longer shoots that can bring pests and diseases to your tree.
How To Choose The Right Tree Fertilizer?

- Test your soil when possible
- Test existing fertilizer
- Consider different types of fertilizer
Choosing the right tree fertilizer is quite a process. The first thing you need to do is test your soil. This will help you to understand what nutrients your tree is getting and what you need to supplement. Your soil should be tested every three years or so, more if the weather seems to be swinging to extremes.
The University of Maryland Extension explains that there are three different types of fertilizer that you should consider for your trees. The first type is the complete analysis granular, which is the most common type of fertilizer for homeowners to use. It is the most affordable and easily available fertilizer (but that doesn’t mean it is the best). People need to use this fertilizer if they tested their soil and you really only need to add nitrogen, not phosphorus and potassium. It can be difficult to find this specific type, so many homeowners often do damage when they fertilize by themselves.
Another option is liquid fertilizer. This is the type most commonly used by tree care and landscaping businesses. It is a precise science of mixing water and the nutrients and injecting them into the soil. Liquid fertilizers aren’t as messy, but tend to be a bit more expensive.
The final option is slow-release nitrogen, which is for trees that are near water resources that cannot have large amounts of nitrogen near them. This is another form that requires a practiced hand.
Your trees should be important to you. In fact, the trees in your yard may be nondescript, but that can have a huge impact on your life. If your trees are giving you trouble or you are just worried about their health, make sure to contact a tree care professional as soon as possible. At Arbortec Tree Service, we serve the greater Denver area. Give us a call at your earliest convenience at: (303) 466-3175. No matter what, we will treat your trees like they are the most important ones in the area – that’s a promise.
Header photo courtesy of Nicholas A. Tonelli on Flickr!