While we love our trees, we often (and unknowingly) do things that can lead to their early demise. This podcast and post discuss five big tree care mistakes (and some of the other most common) that are usually at the root of the problem. Jamie Blackburn, ISA Certified Arborist, was our guest expert for today’s conversation.
Too often, people seek advice for tree problems after it’s too late. If your budget allows, hire an ISA (International Society of Arboriculture) Certified Arborist. It’s the best way to ensure that the person you are hiring to consult with about your tree care is a credentialed, experienced tree care professional.
One of the best reasons for hiring a Certified Arborist is to conduct a general assessment of all your trees prior to known problems. They can work with you to prioritize your goals for safety, tree protection, and maintenance, and develop a plan that works within your budget.
A regular inspection, once or twice a year can be the best plan for catching problems while there’s still time to make corrections. It’s like a wellness visit to your doctor. Many serious problems can be averted by routine visits.
You can find a Certified Arborist through the ISA website. In the United States, TCIA (Tree Care Industry Association) is another organization that can provide referrals to a qualified arborist. In addition, seek to hire an “accredited company”. (TCIA accredited)
Five Big Mistakes in Tree Care
1: Lack of Soil Health – It all comes down to soil health. The same fundamental horticultural practices used for the care of plants also applies to trees. The key is to focus on creating optimal soil health.
Jamie’s approach starts with how healthy can you make the soil to increase soil microbial activity. This provides the greatest return on investment to providing the optimal growing environment for healthy trees. According to Jamie, it all comes down to the root’s interaction with the soil.
Of all the issues related to soil, the biggest problem is almost always compaction. It can be caused by many things, but it is usually by mechanical equipment during or shortly after construction. Yet rainwater impact when soil is soggy, or foot traffic on wet soil can exacerbate compaction problems.
Surprisingly, even when the best of care is provided during construction, the landscaping installation after construction (the final 5%) of the project is often when the most damage occurs.
To avoid compaction problems, limit any construction or landscaping to the area outside of the drip line of the tree. This is not the most precise method but it should be the minimum. Allowing an even larger circumference of undisturbed soil/roots will make for a happy tree.
A thick layer of mulch (3-4 inches of hardwood or pine bark mulch) can buffer the area around tree roots and greatly reduce the impact of potential compaction.
2. Improper Planting – While there are many possible mistakes to improper planting, here are some of the most common problems.
Pull soil away from the trunk flare to find where it meets the root zone. Never allow a tree to be planted deeper than where the trunk flare meets the top roots.
Don’t amend the planting hole with peat moss. Instead, get those roots acclimated as quickly as possible so roots continue to grow. Otherwise, in the planting hole, roots will wind around each other, just like in a plastic container.
Break up native soil, backfill a bit at a time, then water in to knock out air pockets. Then continue to add more soil, then more water (always working to knock out air pockets). Repeat this until planting hole is filled.
Minimize rootball disturbance of a B&B (balled and burlapped) tree.
3: Lack of Supplemental Irrigation to Establish – Even with proper attention at the time of installation, never let the roots become too dry during first growing season. To be safe, keep up with watering during the second growing season as well. It’s usually not until year three that you see the tree really take off.
Therefore, providing supplemental water during the first two full years of growth will provide a much better chance of establishment.
4: Over-fertilization – Nutrient deficiencies are typically not a significant problem for trees since nutrients are usually sufficient in the soil. However, until you get a soil test, there’s no way to know if you have nutrient deficiencies.
A soil test to determine current pH and how to adjust it to suitable levels is likely the best approach to making nutrients already in the soil available for uptake. Improper pH levels can preclude nutrients present in the soil from being available for root uptake. This is usually the most common problem.
Don’t over-fertilize newly planted trees. There’s a good chance the tree or plant you buy is highly juiced up with synthetic nitrogen fertilizer to promote aggressive top growth. Don’t add more fertilizer. Roots need time to come into balance. It takes several seasons for this to happen.
5: Right tree, right place. Just as plants perform best when planted in the appropriate location, trees are the same. Choose the most appropriate trees based on the given location. Trees planted in less than ideal situations, based on their preferred growing environment can create ongoing problems. Yet, even before planting, other important factors should be considered.
- Buy trees from a reputable source to ensure high quality.
- Inspect the tree to ensure it is pest and disease free.
- Look for a good ratio of roots to potting media.
- Make sure roots are not pot bound.
- Inspect the base of the tree for girdling roots. Either don’t buy that tree or change the root configuration.
- Don’t break or cut large roots when planting. A root larger than your thumb in a container grown plant should likely not be cut. While it’s usually better to be over-aggressive with the roots vs. under-aggressive, it’s not a good idea to sever larger roots.
Did you Know…
- Mature, established trees usually benefit from supplemental irrigation in times of drought according to Jamie. But there are a lot of things to consider. Is the tree growing in its native environment? Does the soil has enough organic matter and is it well-mulched to conserve as much moisture as possible in the soil? Sufficient levels can be the greatest help in times of drought.
- Shoot for about one-inch of supplemental water per week in the absence of rain. However, it’s best to water deeply but infrequently. Roots are opportunistic. They grow where available water and oxygen can be found. Frequent, short watering encourages roots to stay near the surface. Conversely, deep infrequent watering will encourage roots to grow deeper to seek moisture. This creates a more drought tolerant tree.
- Trees can usually handle about 20% loss to root zone impact and still recover. Beyond that, professional intervention is likely necessary.
- Construction design changes to minimize the root zone impact can be no more expensive than traditional techniques to resolve an issue to save a tree or minimize root disturbance.
- Adding additional soil over the roots can create root zone disturbance problems. Jamie’s rule of thumb is no more than a half to one-inch fill of dense, compacted soil. Any more can create serious problems. There are exceptions. Loose sandy soil on top of roots can be applied thicker without as much concern.
- Mulch out to the drip line is a great way to solve the problem of trying to resolve the endless battle of covering above-grade roots to level out the surface. It’s an ongoing battle as new roots breach the surface. A loose, coarse mulch layer is a great compromise that won’t threaten the tree.
- When transplanting trees, get as large a root ball as possible. It’s very difficult to dig up enough of the root zone to provide the top growth with what it needs. But don’t cut back the existing growth to try and compensate for the loss of root zone.
- A note on tree topping: Don’t do it. What you don’t know is killing your trees. See the links below for more information.
Links & Resources
Special thanks to Jamie Blackburn, Senior Consulting Arborist / Certified Arborist, Arborguard Tree Specialists
Growing a Greener World television episode on Tree Care (and where you can see my rant on tree topping!)