Deep root fertilization pumps nutrients deeper into the soil than grass roots can reach, giving struggling trees better access to what they need. It’s worth the money if a soil test shows that there is a nutrient problem, but it is a waste of money on trees that are already healthy or that have problems that fertilizer won’t fix.
If you have turf in your yard, it can make life difficult for your trees by out-competing them for water and nutrients in the upper soil layer. Turf roots tend to be dense and a few inches deep, which is typically where fertilizer and irrigation are delivered.
Many types of trees have fine-absorbing roots that operate in the same area. If your tree is in poor health despite your best efforts, you might consider deep root fertilization.
Read on to learn more about this method of providing water and nutrients to your tree.
Tree Care and Tree Fertilization
According to NC State Extension Publications, deep root fertilization, also known as subsurface injection, is a way to deliver liquid nutrients into the soil. It injects the nutrients around 4 to 8 inches deep in a spaced grid under the drip line. This can significantly reduce competition from grass roots.
It’s important to note that this isn’t a treatment for your tree; it’s simply a different delivery method that can sometimes be more efficient and effective.
Deep root fertilization tends to be worth paying for when the following factors are true:
- Nutrition is actually the problem with your tree’s growth.
- Surface application is impractical or wasteful.
- There are other roots, such as those from turf, competing with the tree’s roots.
When to Deep Root Fertilize?
Now, let’s look at some of the main scenarios where deep root fertilization is likely worth it, such as when a soil test points to a nutrient problem. If you carry out a soil test on your yard and it establishes that there’s a fertilization problem, you could potentially get more nutrients to your tree using deep root fertilization. Look out for signs that a soil test is necessary first, such as:
- Reduced annual shoot growth
- Canopy thinning
- Smaller leaves
You’ll need to confirm the causes of the deficiency problem, which may be pests or water presence. Not every cause of nutrient deficiency can be addressed with deep root fertilization, so ensure you’re on the right track.
According to Ann Marie VanDerZanden, another scenario where you might want to use deep root fertilization is when you have young trees that need to establish themselves after settling in. If you have a tree with less than a six-inch trunk diameter, it could respond well to deep root fertilization and ensure better growth and canopy density.
When Is Using Deep Root Fertilization Not Worth It?
It’s not worth it when the tree is mature and already well-rooted in a fertilized yard. Large established trees near lawns and shrub beds that are regularly fertilized almost certainly don’t need any extra because their roots will extend widely across the yard.
If you’re already fertilizing your lawn several times per year, the tree roots are probably adapted to get enough nutrients from around the yard. Deep root feeding methods can be overkill if the real problem is coming from another source.
If you fertilize an already stressed tree, it can make the situation worse because it might push for more canopy growth when the roots can’t support it. Avoid fertilizing trees that are stressed after drought; address moisture problems first, as nutrient uptake requires adequate moisture.
If there are stem issues from problems with the roots, such as root disease, pressure, or excessive moisture from poor drainage, prioritize methods like irrigation and drainage to improve root health.
Deep Root Feeding And Root Zone Nutrients
If the tree is surrounded by lawn and you’re trying to get nutrients below turf roots, it’s one of the main reasons to consider using deep root fertilization. Turf roots only go down a few inches; by injecting nutrients deeper, you make it impossible for the turf to reach them, leaving more for the tree roots below.
In some yards, particularly in urban areas, the soil is much more compacted. While this can be addressed with good watering practices or using mulch, in some cases, it might make sense to use subsurface injection methods.
Frequently Asked Questions
Is Deep Root Feeding Expensive?
According to UMD Extension, you should also bear in mind that deep root feeding is usually much more expensive than techniques like granular fertilizing. If it’s possible to give your tree the nutrients it needs through surface methods, injection might not offer much benefit while unnecessarily draining your bank account.
Is October Too Late to Fertilize?
In North Texas communities like Southlake, Colleyville, Frisco, Grapevine, The Colony, Rockwall, Plano, Richardson, and Allen, October is often still warm enough that trees can take up nutrients, but summer heat and dry spells can leave roots stressed.
Use the following information to decide whether it’s smart to fertilize now, or whether mulch and deep watering should come first:
- Confirm the tree isn’t drought-stressed and that the root zone has adequate moisture before any fertilization.
- Use a soil test (or a clear deficiency reason) before applying nitrogen or other nutrients in the late season.
- If you fertilize, favor conservative rates and avoid pushing late-season canopy growth where early freezes are common.
Deep Root Fertilization and More
As you can see, deep root fertilization is a specialized process that can be very helpful in certain conditions, but it’s an expensive waste of money in others. It’s best to consult with a professional tree service to determine whether you’ll benefit from this method, whatever your tree care needs.
Arbor Tech Tree Service has provided high-quality tree removal, trimming, stump grinding, deep root feeding, and much more since 2009. Our priority is developing a happy and satisfied customer base. We’re not about selling unnecessary services to make a quick buck.
If you’re interested in learning more about our services or want to set up deep root feeding in your yard, we’d love to hear from you. Contact us today and let’s discuss your needs.
