Are your New Jersey trees looking a little worse for the wear this fall? Maybe you noticed your trees had yellowing leaves and stunted growth in the summer. In these cases, your trees may need fertilization this fall to help them deal with limited nutrients in the soil and improve soil structure.
In this article, we will examine fertilizing your trees in the fall. We’ll also look at why and how you should do it and provide tips for improving soil structure.
Key Takeaways
- Fertilizing your trees is crucial to replace depleted nutrients in the soil.
- Look for the typical signs of nutrient deficiency in trees during the summer, including dead patches on the canopy, stunted growth, or discolored leaves.
- A soil test can pinpoint nutrient deficiencies and determine the soil’s pH level and organic matter content.
- Avoid high-nitrogen fertilizers in the fall that will encourage new growth that will die in the winter.
- Improving soil structure by consistently adding organic material to the soil will provide long-term benefits.
The Importance of Fertilizing Trees
Fertilizing trees isn’t as common as it should be, and many homeowners don’t know the importance of providing supplemental nutrients to their trees.
In a forest, trees receive all the nutrients they need from the forest floor, as decomposing leaves and branches add nutrients back into the soil. The trees are also in their natural environment, lowering stress.
Trees in yards, especially urban yards, do not have this same luxury. The soil is not as high-quality (many homes have subsoil rather than topsoil), and the soil does not enjoy the same supplemental nutrients when natural material decomposes. Soil can also become compacted quickly in yards, limiting tree roots’ ability to grow and find water and nutrients.
Trees lacking in the necessary micro and macronutrients will struggle to grow and have lower defenses against problems like insects and diseases.
Fall Fertilization Guide
Fertilization is best left to the professionals, as improper fertilizer use can harm your trees. We’ve prepared a guide so you know what to expect when a professional assists you with fertilization.
A pine tree demonstrating the typical signs of nutrient deficiency. Photo courtesy of Paul A. Mistretta, USDA Forest Service, Bugwood.org.
Keep an Eye on Your Trees For Signs of Nutrient Deficiency
While it never hurts to have regular soil tests for your property, your trees may be giving you warning signs that they are struggling to get the proper nutrition to grow. Some of the common signs that should raise your concern that you need a soil test include:
- Dead or patchy sections of your foliage
- Stunted or lower growth than in previous years
- Yellow or discolored leaves
- Increased insect activity
- Premature leaf drop
PRO TIP: While these are common symptoms of a tree with nutrient deficiency, it is not a definitive answer. Conduct a soil test before applying any fertilizer.
Have a Professional Conduct a Soil Test
First and foremost, fertilization should always seek to correct for a deficiency present in the soil. Using a general fertilizer instead of a targeted application can result in damage to the roots and the tree as a whole.
A soil test will determine what your soil lacks and let you know the best course of action. Soil tests measure several factors, including:
- Nutrient Content: You will have a complete report on the levels of macronutrients (nitrogen, phosphorus, and potassium) and micronutrients (calcium, sulfur, and magnesium, among others) in the soil.
- pH Level: Knowing if your soil is acidic or basic will allow you to better plan what to add.
- Organic Matter: The test will provide information on how much organic matter is in the soil, a crucial element for healthy soil.
- Cation Exchange Capacity (CEC): CEC measures how well your soil can retain and exchange cations (positively charged ions). An arborist can explain to you how these results will affect your soil’s ability to retain nutrients.
PRO TIP: For more information on soil tests, see our previous article on the subject. Why Soil Testing is Important for Tree Health in Northern New Jersey
Proper fertilization can help trees remain healthy and your leaves green, like these oak leaves.
Use the Right Fertilizer for Your Soil
Your soil test should have revealed any deficiencies. Knowing what your tree needs will allow an arborist to create a specialized cocktail with the proper proportion of nutrients for a perfect balance for your tree. Avoid applying fertilizer yourself if you don’t know how to read the label or how much of a nutrient your trees need.
In the fall, you’ll want to avoid using fertilizers high in nitrogen. Nitrogen is the primary nutrient that spurs growth in trees, and applying it in the fall will encourage a tree to put out new growth right before dormancy.
This new growth stresses a tree in two ways. First, the tree will expend the energy it needs to get through the winter on putting out this new growth. Second, this new growth is likely to die in the winter, further stressing the tree.
In general, we recommend slow-release fertilizers in the fall that will slowly be absorbed by the soil and roots throughout the winter.
Timing is Crucial
For fall fertilization, we recommend waiting until later in the season before you apply any fertilizer. As a general rule of thumb, wait until the last days of October at the earliest before fertilizing. You should complete any fertilization before the ground freezes, so try to finish it by late November or early December.
Use Fertilizer Sparingly
Fertilizer applications should be targeted and precise. Applying too much fertilizer can cause fertilizer burn to the roots of a tree. The soil may not be able to take in the nutrients. When fertilizer sits on the surface for too long, it can eventually erode and end up in rivers or other bodies of water.
Avoiding erosion is especially important, as the fall can sometimes be wet in Northern New Jersey. For instance, in 2023, in Essex County, residents saw 16.53 inches of rain between September and November.
Work Toward Improving Soil Structure
We treat fertilizer as a bandage for nutrient-deficient soil but not a cure. Fertilizers can provide supplemental nutrients to the soil, but these nutrients will be used by the tree, putting your soil back to square one. Improving soil structure will give you longer-term benefits than simply fertilizing.
At Aspen Tree, we offer a few techniques to help you improve your soil structure. We offer radial mulching, where we add mulch to the soil, allowing it to decompose and provide nutrients to the tree’s roots. We also offer soil aeration to break up compacted soil and better enable your tree’s roots to grow.
Adding organic matter to your trees can also improve your soil structure. Consider gathering up the leaves around your tree this fall and composting them to use as organic matter. Just be sure you hot compost any leaves with signs of foliar fungus.
Aspen Tree Can Help When Your Trees Need Fertilizer
Fall fertilization is about more than just spreading a bag of fertilizer around your tree. It is a delicate process that requires extensive knowledge of arboriculture. In addition to providing supplemental nutrition through fertilization, we also recommend working to improve your soil’s structure every year by adding organic matter.
If you need help with your fall fertilization, the team at Aspen Tree can help. We will ensure your tree gets exactly what it needs at the right time. Call us today at 201-939-8733 or request a quote online to get a consultation and set up a fertilization schedule.
