September 15, 2016
Plant it high, never die
By Dave Braun
LO President
All too often, trees planted in our landscape die unnecessarily. I don’t have to tell anyone the enormous costs of replacing trees; from the cost of labour to the cost of the tree, from the loss of productivity for the crew to the loss of reputation of our companies, it’s something that can cost us deeply.
Last month, I received a call from one of our customers who had an issue on his site. He had a number of trees that were in decline and a number that were dead. When I visited the site, I was surprised that any of the trees survived. The trees were buried five inches below grade and then had almost a foot of mulch on top, creating a “landscape volcano,” which was suffocating the plant. Fortunately, we can increase tree survival by avoiding a few common mistakes.
The biggest cause of tree death and decline that I see on landscape sites is trees that have been planted too deeply. Trees need drainage and oxygen to survive, and will drown if they are just one inch below grade. The old adage, “Plant it High, Never Die,” is a mantra to which all of your staff should adhere.
In most cases, trees should be planted with the root collar at least three to four inches above grade. Planting your trees with a quarter of the root ball above grade is another good rule of thumb. Any aesthetic issues caused by planting trees slightly higher can be solved by gently grading the area to make a slight mound around the tree. Dead trees that are perfectly at grade never look good. Also, if the hole is inadvertently dug too deep, add soil to the bottom of the hole and compact it with your foot.
Sometimes the root collar is actually buried in the root ball when the contractor receives the tree. In this case, it’s important to scrape off the top of the root ball to expose the root collar to determine the correct planting depth. When considering the width of the hole, it should be at least one and a half times the width of the root ball (more is ideal). The young fibrous roots of the new tree will grow much better in disturbed soil. These new roots cannot grow in air, so it’s important to continuously pack the soil with your feet as you plant, not just at the end of the process (step firmly, but don’t pack hard). Also, when mechanical equipment is used to dig holes, it’s critical to make sure that the sides of the hole have not been “glazed,” creating a hard wall that new roots cannot penetrate.
Do not place more than one inch of mulch directly over the root ball on newly planted trees (too much will decrease soil oxygen). Piling mulch around the trunk should also be avoided to prevent bark decay. I’ll say this again, less is more — one inch is plenty! As a rule of thumb, when you’re applying mulch away from the root ball, three to four inches of wood/bark chips can work well for weed control and preventing soil compaction. On wet soils, however, mulch may hold excess moisture, and also isn’t suitable in particularly windy areas.
A general rule of thumb is one inch of water per week. Watering can be a significant expense, but is very little compared to the full cost of replacement.
Finally, do not remove the wire basket, as this will only damage the roots. Unless there is unnatural fibre (e.g. plastic twine), or an excess amount of sisal rope or burlap, it’s unnecessary to remove the tree from its packaging. The remaining lacing helps to stabilize the tree against the wind and will decompose within the season.
Sometimes, tree planting specs can be contrary to the health of the tree. It is our responsibility to use our knowledge and ensure healthy trees for our communities.
LO President
All too often, trees planted in our landscape die unnecessarily. I don’t have to tell anyone the enormous costs of replacing trees; from the cost of labour to the cost of the tree, from the loss of productivity for the crew to the loss of reputation of our companies, it’s something that can cost us deeply.Last month, I received a call from one of our customers who had an issue on his site. He had a number of trees that were in decline and a number that were dead. When I visited the site, I was surprised that any of the trees survived. The trees were buried five inches below grade and then had almost a foot of mulch on top, creating a “landscape volcano,” which was suffocating the plant. Fortunately, we can increase tree survival by avoiding a few common mistakes.
The biggest cause of tree death and decline that I see on landscape sites is trees that have been planted too deeply. Trees need drainage and oxygen to survive, and will drown if they are just one inch below grade. The old adage, “Plant it High, Never Die,” is a mantra to which all of your staff should adhere.
In most cases, trees should be planted with the root collar at least three to four inches above grade. Planting your trees with a quarter of the root ball above grade is another good rule of thumb. Any aesthetic issues caused by planting trees slightly higher can be solved by gently grading the area to make a slight mound around the tree. Dead trees that are perfectly at grade never look good. Also, if the hole is inadvertently dug too deep, add soil to the bottom of the hole and compact it with your foot.
Sometimes the root collar is actually buried in the root ball when the contractor receives the tree. In this case, it’s important to scrape off the top of the root ball to expose the root collar to determine the correct planting depth. When considering the width of the hole, it should be at least one and a half times the width of the root ball (more is ideal). The young fibrous roots of the new tree will grow much better in disturbed soil. These new roots cannot grow in air, so it’s important to continuously pack the soil with your feet as you plant, not just at the end of the process (step firmly, but don’t pack hard). Also, when mechanical equipment is used to dig holes, it’s critical to make sure that the sides of the hole have not been “glazed,” creating a hard wall that new roots cannot penetrate.
Do not place more than one inch of mulch directly over the root ball on newly planted trees (too much will decrease soil oxygen). Piling mulch around the trunk should also be avoided to prevent bark decay. I’ll say this again, less is more — one inch is plenty! As a rule of thumb, when you’re applying mulch away from the root ball, three to four inches of wood/bark chips can work well for weed control and preventing soil compaction. On wet soils, however, mulch may hold excess moisture, and also isn’t suitable in particularly windy areas.
A general rule of thumb is one inch of water per week. Watering can be a significant expense, but is very little compared to the full cost of replacement.
Finally, do not remove the wire basket, as this will only damage the roots. Unless there is unnatural fibre (e.g. plastic twine), or an excess amount of sisal rope or burlap, it’s unnecessary to remove the tree from its packaging. The remaining lacing helps to stabilize the tree against the wind and will decompose within the season.
Sometimes, tree planting specs can be contrary to the health of the tree. It is our responsibility to use our knowledge and ensure healthy trees for our communities.
Dave Braun may be reached at dbraun@landscapeontario.com.