Tree health for homeowners: Learn the benefits of deep root fertilization
Updated: Feb 16
I’m sure you’ll agree when we say the weather in New Jersey was off-the-charts crazy this year. Heat waves followed by deluges followed by disease-promoting humidity followed by … you get the idea. Throw in the presence of pests like the Spotted Lantern Fly and it’s no wonder that landscapes are limping along as we wrap up summer.
Just as you would grab for a post-workout boost of support from an energy bar or energy drink, trees also benefit from the boost provided by a fall feeding. Nutrients such as Nitrogen, Phosphorus and Iron help keep the leaves healthy, the roots growing and the trees’ cells stronger overall. And the healthier a tree’s cells are, the better it can survive the impacts of the pests that feed on them—namely, the Spotted Lantern Fly. This shot of nutrients in the fall helps both as a way to recover from what’s been a difficult growing season and as a way to prepare them for next season.
Do I really need to fertilize my trees? Yes, here's why.
“But forests don’t need fertilizer injections,” you’re saying. True! A tree actually provides its very own fertilizer! When its leaves drop in fall, they surround the tree, break down slowly over the winter and release all their nutrients into the soil where the trees then reabsorb them. Talk about the circle of life!
But our inclination for our own residential trees is to blow the leaves away or bag them up for removal for a leaf-free yard. When we do that, we’re removing nature’s own method of fertilization. And that’s why we fertilize.
What Is Deep Root Fertilization?
Unlike, say, a general application of a granular fertilizer on the soil surface under a tree, Deep Root Fertilization places the nutrients directly into the soil where the roots can more easily absorb them. The treatment process itself uses special pressurized equipment to inject fertilizer and organic matter formulations to a soil depth of about 5-6 inches. The “feeder roots” that perform the task of absorbing nutrients for the tree occur most densely within that upper layer of soil. The injections take place in numerous spots under the canopy of the tree to ensure the entire root system has access to these nutrients.
Why is deep root fertilization better than granular, or topsoil fertilizers?
Applying granular fertilizers to the soil’s surface under a tree canopy really isn’t the most efficient way to deliver the nutrition your trees need. These granular fertilizers can:
Wash away before penetrating into the soil.
Can contribute to nutrient overloading of rivers and lakes when washed away.
Be taken up by the grass before reaching the tree’s root zone.
Can take a really long time to find their way to the feeder root zone.
When should I fertilize my trees?
The best time to fertilize trees is mid-September until the injectors can longer be inserted into the ground, just when the soil freezes. If you’re dealing with healthy trees, performing Deep Root Fertilization for your trees can take place every other year.