Residents Visitors Business Leisure I Want To...
Public Safety
City Services
Online Services
Top Ten Mistakes People Make With a Newly Planted Tree 
  1. Water it heavily two or three times a week so the planting hole fills up with water.
  2. Water it lightly every day or so. This will ensure that the bottom half of the root system is bone dry while the top half is just wet enough to stop the flow of life-giving air (oxygen) to the entire root system
  3. Never water the tree in order to avoid over-watering the tree.
  4. Grow grass tight to the base of the trunk. This will effectively stop both the flow of water and air to the roots. Have you ever noticed that forest floors are virtually devoid of grass while prairies are devoid of trees?
  5. Plant a tree in July and then leave for the mountains to avoid the heat.  If you plan on being gone for 10 days or more you may as well take the tree with you because it’ll be dead when you get home.
  6. Plant it in a newly sodded lawn which requires two or three waterings per day.
  7. Don’t bother staking the new tree so that all the new root growth is broken as the tree rocks back and forth in Colorado’s gale force winds or even better if the tree is an evergreen and blows out of the ground altogether.
  8. Plant the tree a couple of inches too deep so that the roots suffocate or six inches too high so the roots have no soil contact to grow into.
  9. If the tree insists on living even though you’ve followed the above instructions to the letter, bang the trunk every now and again with the lawn mower.
  10. The lawn mower won’t finish it off; hire a neighbor kid with a weed-eater to clear away the grass near the trunk. This works every time.

List courtesy of Left Hand Valley Nursery

We can laugh at this Top Ten list, but truly, it can be complicated and confusing to figure out what a newly planted tree needs to thrive and grow. Thornton has many new homeowners that are facing these very issues. You may have a young tree out in the yard at this moment or plan to plant a tree this spring so let’s take a look at the common mistakes people make caring for a newly planted tree. A new tree needs enough water to keep the roots in the root ball moist without being saturated. It also needs enough water in the native soil surrounding the root ball to coax the roots to grow outward into this area.

Too much water applied to a heavy clay soil and the water displaces the oxygen in the tiny air spaces in the soil. Oxygen is just as vital to tree roots as water and without it the tree roots cannot keep taking up water because they are suffocating. This causes the leaves to wilt a bit and the caring and concerned owner of the new tree get’s the hose out and applies more water. Now, the tree really starts to wilt as the roots die and start rotting and you get the picture, more watering, more suffocation….DEAD TREE. When you dig up the dead tree and the soil smells like the black gunk you pull out of the shower drain you can bet it drowned.

If you live on the site of an old streambed and have sandy soil you can usually relax and water your tree more often without worrying about drowning it. But, you are that owner that cannot take a ten day vacation in July without hiring a tree sitter to water while you are gone. A newly planted tree has a very limited root system, concentrated in the root ball, and will not be fully established until the roots grow into the surrounding soil.

Don’t fall for the mistaken notion that because you bought a drought resistant tree species it doesn’t need ample water to get established. The “low water- use” thing kicks in when the tree is fully established with a good hearty root system under the ground to match the size of the leaf canopy.

Bottom line on new tree watering: find a nice long screwdriver and poke it into the root ball and surrounding soil. If it is moist down as far as you can poke it, wait on the watering. When the soil feels like it is drying out in the root ball area, water just enough to wet the root ball and about a foot out into the surrounding soil. A two inch caliper deciduous tree or six foot tall evergreen needs about 20 gallons of water a week. Water slowly all in one sitting and wait a week before you water again to let the soil dry out somewhat (that oxygen thing again). My favorite trick: poke holes in the bottom of a 5 gallon bucket. Place it over the root ball and fill the bucket and let it slowly empty by seeping into the root ball. Do this three more times all around the root ball. Voila, you’ve just watered your tree for the week without saturating the soil.

Let’s talk about what to do when the landscaper has just installed a new lawn along with the new trees planted smack dab in the middle of the sod areas. This situation presents a huge risk of drowning death for the new trees. The best way to deal with this is to leave a large circle (6 foot diameter) with no sod around the trunks of the trees. Don’t mulch this circle until the sod is established and the irrigation has been cut way back to normal levels.  The idea is to allow as much air circulation in the soil around the root ball as possible while the new sod is getting established. Many homeowners fail to scale back the time on the clock and keep right on watering at the “new sod” level. This is expensive, wastes water and causes very shallow rooting for the new grass (that oxygen thing again). If you can’t understand your irrigation controller, (and don’t beat yourself up, I have spent hours perched over the laundry bins trying to get mine programmed correctly) get the company that installed it on the horn and have them come adjust it.

The other nice thing that the no- sod circle around each tree accomplishes is that it allows the tree roots to grow without the competition of grass. Studies have shown that clearing the turf grass away from the root zone of newly planted trees can dramatically increase the growth of those trees.

Covering the root ball with a few inches of shredded wood mulch will dramatically cut back on your watering but can block the needed oxygen in the soil so it is better to skip the mulch until the tree is well established if you have heavy clay soil. If you are one of the sandy soil homeowners or the tree is planted in a shrub bed with drip irrigation, mulch away. Never pile mulch up against the base of the tree trunk (for any age tree) as these “mulch volcanoes” will hold moisture against the bark; where you do not want it.

Whew, watering just took up most of this article so I better get a move on.
Stake a tree if it is on a slope, in a windy area (I know, that’s everywhere in Thornton), has a tiny root ball compared to the canopy and especially if it is an evergreen. Evergreens catch more wind and have root masses like a dinner plate. They go over like those portable basket ball hoops.

You don’t have to stake a tree that is shorter than you unless you need to mark where it is located in the winter so you don’t roll over it with the snow blower. Ditto on multi-stem trees; they just don’t tend to blow over and it is good for the trunks to move in the wind. The wind movement stimulates the tree to make stronger tissues in the trunk so you end up with a healthier tree. Staking is detrimental if the stakes are left on too long and the guys start to dig into the live tissues that are just under the bark. Take the stakes off after one year or don’t bother staking. More trees are killed by tight guys restricting the trunk growth than by blowing over!

Another method of young tree homicide is perpetrated by well meaning folks and it’s an agonizing death. Every nick out of the base of a tree by the string trimmer is a major blow to the tree. Contrary to what most people think, the live tissues in a tree are not deep inside the trunk but fit like a sock around the tree just under the thin layer of the bark. If you wound the tree at the base you have just cut off all circulation to the upper parts of the tree above the wound. The tree will be stunted by that wound forever and may never reach its full potential. Some of these damaged trees hang on for years.  Wounds are the primary conveyers of decay, cankers and blights. So, if the interrupted circulation doesn’t kill the tree, a disease will eventually get in there and choke the life out if it. Take a look around town at the difference between beautiful healthy trees and the pathetic ones. I bet the base of the lousy looking trees look like they got mangled by wolves. Bottom line: String Trimmers kill trees. Keep the grass from growing up to the trunk in the first place.

It is a very good idea to wrap the trunks of your newly planted trees from October until April to protect the thin bark from cracking in our widely fluctuating temperatures. Young maples, lindens and honey locusts are especially susceptible to these frost cracks. Once the tree has a trunk wound it the same sad story of the last paragraph.

Hopefully, you know a little more about taking care of your new tree now. We’ll have another article on mature tree care coming up soon. I’m out of room and there is a tree that needs a hug.

Heidi Feigal is the Senior Landscape Architect for the City of Thornton, a Certified Arborist and lifelong tree lover.

City of Thornton
9500 Civic Center Drive, Thornton, CO 80229
Contents ©2014 City of Thornton
All rights reserved