You have trees. You want them to have proper nutrition, but how do you make sure that happens? Well, first, you need a little bit of an understanding of a tree’s natural habitat and how it obtains its mineral nutrients. Trees are built to thrive in nature. They draw life from nutrient dense soil, plentiful water and interactions with wildlife. Growing trees in an urban environment may be a little difficult, but it is by no means impossible. People do it all the time.
To help with your gaps in knowledge, you should consider consulting with our certified arborist to develop a nutrient management program for your trees. You should also be willing to apply supplements as needed. We, at Austin Tree, can really help you decide what the best nutrition for your trees should be.
A regular application of fertilizer might be necessary to ensure that your trees have adequate nutrition. Fertilizers may be natural or synthetic. However, they must aim to provide trees with proper nutrients. The common objectives of fertilization should be:
- To overcome a visible nutrient deficiency,
- To eliminate a deficiency that’s not obviously visible but that was detected through soil or foliar analysis,
- To increase vegetative growth, flowering or fruiting,
- And to increase the vitality of the plant.
Fertilizer and Soil pH Levels
Most professional arborist practice ‘prescription fertilization’, which means that they only apply nutrients that are found to be deficient. Why? Liberal fertilization can ruin your soil’s pH balance. That is not good for your tree at all. An unbalanced pH will affect the availability of many nutrients. We know that nutrients are vital to a tree’s health, but they should never be added if they compromise your soil’s pH levels. To avoid this problem, measure your soil’s pH level before you apply fertilizer or consult us.
Measuring pH Levels
The pH scale measures how acidic or basic a substance is. It ranges from 0 to 14 with 7 being the neutral value. A pH level less than 7 is acidic, while a pH greater than 7 is basic. Homeowners can take a soil sample and send it to their local university cooperative extension service. Your best bet is to call us to perform a soil test. (You can visit this website to learn how to take a soil sample.) We can make custom recommendations based on the results of the soil sample analysis. Please note that pH levels can change over time, so be sure to conduct follow-up tests and adjust your soil accordingly.
Choosing a Fertilizer
Professional tree care services have access to slow-release fertilizers or can tell you where to get them. These are formulated for your tree’s health. Often, professional slow-release fertilizers reduce the need for repeated treatments over the course of the growing season. When choosing an appropriate fertilizer for trees, you need to have a fertilizer with the following qualities:
- Features at least 50% slow-release,
- Has a salt-index of less than 50 (salt is not good for tree health),
- And does not have high ratios of potassium and phosphorous. Trees don’t like 10-10-10 fertilizers.
Fertilizer Application Methods
Once you’ve gone ahead and selected your fertilizer, it’s time to apply it. Fertilizer should be applied prior to soil prior to planting. As your tree grows, you’ll need to develop alternate methods for fertilizer application.
Surface Application – This works best when there’s no turf or ground cover over the roots. Liquid surface application can be made using a variety of spray equipment. To achieve an even distribution of fertilizer, a flooding tip or water breaker nozzle is preferred for surface application. Dry fertilizer can be used but needs to be watered-in. Do not use surface applications where runoff can occur.
Subsurface Application – This method requires you to drill holes 2-4” wide to a depth of 4-8” and pouring a specific amount of fertilizer into each hole. There should be at least 2 inches between the top of the fertilizer and the surface of the soil. The fertilizer should be equally distributed among all holes. Drill holes in a grid pattern, with holes spaced 12 to 36 inches apart. This method is labor-intensive and can damage roots so it shouldn’t be your go-to fertilizer application. Professional tree companies like us can provide a subsurface liquid injection with slow-release fertilizer as an alternative.
Foliar & Trunk Application – You can apply a fertilizer to foliage, or it can be injected directly into the tree. Foliar spray or trunk injections should not be your first course of action. They should be reserved for rare cases when soil application is not effective or practical to apply. This is an advanced application and is best done by a professional.
If you correctly select and apply a slow-release fertilizer formulated for your tree, you should only need to apply 2 to 4 pounds of nitrogen per 1,000 square feet of application. The total application for a growing season should not exceed 6 pounds of nitrogen per 1,000 square feet.
Now, we know that nutrition for trees is not an exact science, but an expert opinion can be invaluable. We hope you’ll trust us at Austin Tree Service to provide that expert opinion. We want to keep your trees healthy and well fed. Give us a call today at 512-341-8888.