There are many rumors out there that somehow become common knowledge that are very detrimental to whatever the cause is. Planting trees is one of them. I am so saddened when I see trees mulched up to their lower branches, called ‘Mulch Volcanoes’. Professional landscapers do it all the time for two reasons, one, to sell you more mulch and to not have to come back anytime soon to remulch you. Sadly, homeowners see this and think this is the way to go and the vicious cycle continues.
S I G H…
Now, let me teach you how to plant your tree correctly, so you can enjoy your newly planted tree for your lifetime!
We’ll start with a quick pictorial summary, then delve into the details afterward!
This was a small, PeeGee Hydrangea (Hydrangea paniculata Grandiflora) on a standard. It had been grown in a container, but is in B&B (Balled & Burlaped) format now as a client did not like it, we had to remove them from their yard and I was the lucky recipient of two free trees! As they were small and the rootball was solid, I chose to remove the burlap first (not recommended for amateurs!!) I felt the top to find the roots, which were right at the top. I dug my hole 3X larger than the rootball.
I moved the tree into the hole, by holding the rootball, NOT by picking up the tree by the trunk! I back-filled it about halfway with native soil and watered. After that water soaked in, I filled the remainder of the hole and watered again. Notice how I did not put any soil on the rootball? Be sure to water your new trees regularly. One long soak is better than three fleeting waters. I love these type of Gator bags more than the Teepee types as they somewhat settle the soil with their weight and they will fit on bushy shrubs also.
This tree is planted at perfect grade. It is about 1″ – 2″ higher than the soil around it. Next year, I will dig the grass out in between them and add some groundcover. For now, the grass is an insulator.
So, without further adieu: How to Plant a Tree Like a Licensed Arborist!
Determine the depth of the top roots in the root ball
- Systematically probe the root ball with a slim rod or screwdriver. At least two structural roots should be found in the top 1” to 3” inches of soil, 3” to 4” inches out from the trunk. On species prone to trunk circling-roots*, the top structural root should be within the top one inch of the root ball. If any circling roosts are found, prune them out.
- If the tree has too much soil on the root ball, excess soil should be removed from the top in the backfill step of the planting process.
Dig a saucer-shaped planting hole three-times the root ball diameter
- To maximize soil oxygen levels, plant the tree 1” to 2” inches above grade
- The root ball MUST sit on undug soil, which stabilizes the tree and prevents sinking and tilting. Measure after each shovel-full if you have to!
- A saucer-shaped planting hole allows the root system to grow rapidly to 400% of the root ball volume before being slowed by the lower oxygen levels in the site soil. This is enough to minimize post-planting stress in normal planting situations.
- The wide, saucer-shaped planting hole gives the tree more tolerance to over-watering and waterlogged soils. The wide planting hole also allows for root ball wrappings to be removed after the tree is situated in the planting hole.
- A labor-saving technique is to dig the planting hole about two times the root ball diameter with somewhat vertical sides, then widen the hole into the desired saucer shape with the shovel during the backfill process.
Set the tree into place, and remove container/wrappings
- In setting the tree into the planting hole, if the tree has a “dogleg” (a slight curve in the trunk just above the graft) the inside curve must face north to avoid winter bark injury. This is a good practice to follow, however if you must place it differently because of aesthetics, you may need to wrap the trunk the first couple of winters to prevent sun scald on the trunk.
- Vertically align the tree, with the top centered above the root ball. Due to curves along the trunk, the trunk may not necessarily look straight.
In this step, techniques vary for Container-Grown Trees and Balled And Burlapped (B&B) Trees.
Container-Grown Nursery Stock:
Container-grown nursery stock describes a variety of production methods where the trees or shrubs are grown in the containers (limiting root spread to the size of container). In some systems, like pot-in-pot and grow-bags, the container is in the ground. An advantage of container stock is that it can be planted in any season.
- Lay the tree on its side in or near the planting hole.
- Wiggle off or cut off the container.
- Shave off the outer 1-1½ inches of the root ball with a pruning saw or pruners. This is to deal with circling roots.
- Tilt the tree into place with the inside curve of any graft crook facing north.
- Check the depth of the root ball in planting hole. If needed, remove the tree and correct the hole depth.
- Align vertically.
- For stability, firm a shallow ring of soil around the bottom of the root ball
- The ideal container-grown tree has a nice network of roots holding the root ball together. After the container is removed, the tree is gently tilted into place.
If most of the soil falls off the roots, the tree is planted as a bare-root tree.
If some of the soil falls off (often on the bottom), it may be necessary to adjust the depth of the planting hole. Backfill and pack the bottom of the planting hole to the correct depth.
- Fabric grow bags must be removed from the sides. They are generally cut away after setting the tree into place.
- Paper/pulp containers should be removed. Most are slow to decompose and will complicate soil texture interface issues. Pulp containers often need to be cut off, as they may not slide off readily.
- In handling large trees (3-inch caliper and greater) it may be necessary to set the tree into place before removing the container.
Field-Grown, B&B Nursery Stock:
Field-grown, balled and burlapped (B&B) trees and shrubs are dug from the growing field with the root ball soil intact. In the harvest process, only 5-20% of the feeder roots are retained in the root ball. B&B nursery stock is best transplanted in the cooler spring or fall season.
To prevent the root ball from breaking, the roots are balled and wrapped with burlap (or other fabrics) and twine (hence the name B&B). In nurseries today, there are many variations to the B&B techniques. Some are also wrapped in plastic shrink-wrap, placed into a wire basket, or placed into a pot.
An advantage of the wider planting hole is that it gives room for the planter to remove root ball wrappings AFTER the tree is situated in the hole.
Based on research by the ISA, standard procedures are to remove root ball wrapping materials (burlap, fabric, grow bags, twine, ties, wire basket, etc.) from the upper 12 inches or 2/3 of the root ball, whichever is greater, AFTER the tree is set into place. Materials under the root ball are not a concern since roots grow outward, not downward. It is still a good idea to remove as much as possible.
- Remove extra root ball wrapping added for convenience in marketing (like shrink-wrap and a container). However, do NOT remove the burlap (or fabric), wire basket and twine that hold the root ball together until the tree is set into place.
- Set tree into place with the inside curve of any graft crook facing north.
- Check the depth of the root ball in planting hole. If needed, removed the tree and correct the hole depth.
- Align vertically.
- For stability, firm a shallow ring of soil around the bottom of the root ball.
- Removed all the wrapping (burlap, fabric, twine, wire basket, etc.) on the upper 12 inches or upper 2/3 of the root ball, whichever is greater.
- If roots are found circling the root ball, shave off the outer 1-1½ inches of the root ball with a pruning saw or pruners.
- The consensus from research is clear that leaving burlap, twine, and wire baskets on the sides of the root ball are not acceptable planting techniques.
- Burlap may be slow to decompose and will complicate soil texture interface issues.
- Burlap that comes to the surface wicks moisture from the root ball, leading to dry soils.
- Jute twine left around the trunk will be slow to decompose, often girdling the tree.
- Nylon twine never decomposes in the soil, often girdling the trees several years after planting.
- Wire baskets take 30-plus years to decompose and may interfere with long-term root growth.
- With tapered wire baskets, some planters find it easier to cut off the bottom of the basket before setting the tree into the hole. The basket can still be used to help move the tree and is then easy to remove by simply cutting the rings on the side.
When backfilling, be careful not to over-pack the soil which reduces large pore space and thus soil oxygen levels. A good method is to simply return soil and allow water to settle it when irrigated.
Soil “peds” (dirt clods) up to the size of a small fist are acceptable in tree planting. In clayey soils, it is undesirable to pulverize the soil, as this destroys large pore space.
Changes in soil texture (actually changes in pore space) between the root ball soil and the backfill soil create a soil texture interface that impedes water and air movement across the interface. To deal with the interface, the top of the root ball must come to the surface (that is, no backfill soil covers the top of the root ball). Backfill soil should cover the root ball knees, gradually tapering down.
When properly planted, set on undug soil, most trees in the landscape do not require staking or underground stabilization. Staking may be desirable to protect the trees from human activities. Staking or underground stabilization may be needed in windy areas.
Install staking before watering so the planting crew does not pack down the wet soil. After the first year, remove the stakes for two reasons, one to be sure growth is not hindered by any cables and secondly, the tree will need to learn how to deal with the wind, if left staked, it may blow down after it’s larger.
Water to settle soil
Watering is done after staking so the installer does not compact the wet soil installing the stakes. Watering is a tool to settle the soil without overly packing it.
Be sure the new tree gets enough water to settle the soil, then at least 1” of water a week, more if it is hot and dry.
With the wide planting hole, the backfill soil may settle in watering. Final grading may be needed after watering.
Do not place mulch directly over the root ball on newly planted trees. As a rule of thumb, 3” to 4” inches of wood/bark chips gives better weed control and prevents soil compaction from foot traffic when placed over the backfill area and beyond. Additional amounts of mulch may reduce soil oxygen.
Do not place wood/bark chips up against the trunk. Do not make mulch volcanoes!! On wet soils, mulch may help hold excessive moisture and be undesirable. Wood/bark chips are not suitable in open windy areas.
- These species are prone to girdling roots.
Austrian pine, Pinus nigra
Black gum tupelo, Nyssa sylvatica
Bradford pear, Pyrus calleryana
Bur oak, Quercus macrocarpa
Cherry, Prunus spp.
Crabapple, Malus spp.
Dogwood, Cornus spp.
Elm, Ulmus spp
Fruitless mulberry. Morus alba
Gingko. Gingko biloba
Green ash, Fraxinus pennsylvanica
Hackberry, Celtis occidentalis
Hemlock, Tsuga canadensis
Holly, Ilex spp.
Honeylocust, Gleditsia triacanthos
Juniper, Juniperus spp.
Littleleaf linden, Tilia cordata
Norway maple, Acer platanoides
Norway spruce, Picea abies
Pin oak, Quercus palustris
Poplar/Cottonwood, Populus spp.
Red maple, Acer rubrum
Red oak, Quercus rubra
Sawtooth oak, Quercus acutissima
Scotch pine, Pinus sylvestris
Shumard oak, Quercus shumardii
Siberian elm, Ulmus pumila
Silver maple, Acer saccharinum
Spruce, Picea spp.
Sugar maple, Acer saccharum
Sugarberry, Celtis laevigata
Sweetgum, Liquidambar styraciflua
White oak, Quercus alba
White pine, Pinus strobes
Zelkova, Zelkova sp.