Colorado Master Gardener Training Planting Trees
Roots only grow with adequate soil oxygen levels.
Tree root systems are typically shallow and widespread.
Sinker roots follow natural openings into deeper soil.
Fine roots are present near the soil surface through the entire root system.
Roots only grow with adequate soil oxygen levels. Tap-root 3% of trees have a tap root system. Plate-root * 83% of trees have a lateral root or plate-root system with shallow, spreading roots. Heart-root 15% of trees have a heart-root system where roots grow at a variety of angles.
Top primary root should be 1” below soil surface
Height of Soil on Root Ball On a tree planted too deep, wind movement rocking the tree may create a soil gap around the trunk. Note no flare. Top primary root 1” below soil surface Look for root flare
Planting Hole Depth To prevent sinking and tilting, the root ball sits on un-dug (firm) soil.
Planting Hole Depth Top of root ball: 2-3” above original soil grade original soil line new soil line Rootball sits on firm,undisturbed soil. Top spreading root 1” below soil surface
A hole three times the diameter of the root ball with sloped sides will allow the root system to grow rapidly to 25% of its original size before being slowed by the poorer quality site soil-- enough to avoid extreme stress under normal conditions.
The Saucer-Shaped Hole If roots have difficulty penetrating compacted site soil, sloped sides allow roots to continue to grow vigorously towards the better soil near the surface rather than being trapped in the planting hole.
Tree Planting Tree sits on undisturbed soil. Backfill hole 2-3 times wider than root ball Top of root ball 2-3” above grade. Top primary root 1” below root ball surface.
Options: Planting Hole Size How wide is adequate?
Post planting stress
Knowledgeable work crew
Planting on Sandy Soils Plant at original soil line wood chip mulch original soil line
Planting in compacted clay soils Soil ball 1/3 above original soil line original soil line new soil line Cover “knees” bark/wood chip mulch
Planting Bare Root Trees Roots spread on mound of firm soil. Planting depth: Top primary root 1” below soil level 1-2” (level on sandy soils) original soil line Saucer-shaped planting hole 1-2 feet wider than root spread
Is the tree staked due to standard practice or need?
Correctly planted trees on firm soil generally don’t need staking
Trees > 4” caliper may need guy lines. Try to attach at 8-10” intervals Guy lines at 45 0 angle 4” caliper -- 3’ long stake 8” caliper -- 4’ stakes Deadman at right angle to guy lines Limited movement stimulates root development.