Tuesday 17 May 2005

So You Still Want to Plant a Tree

May 17, 2005,

How to dig a fifty dollar hole for a five dollar tree.

The number one mistake made when planting trees is to make the planting hole too small. A properly dug planting hole is broad and shallow, two to three times as wide as the root ball and slightly shallower. It should be dish shaped sloping down to the deepest part below where the plant will sit. Do not place gravel in the bottom of the planting site as this will result in water being trapped in the finer soil on top of the gravel. This is called a perched water table, and often causes root death from drowning. If you site has poor drainage consider installing drain tiles to help improve the situation.

The number two mistake made in planting trees is to plant them too deep.

Roots need to breath, and don’t grow upwards readily. It is much better to plant trees “high and proud” as the saying says, than it is to have buried them in a shallow grave. More than one group of trees of different sizes has been evened up by planting the tallest one a little deeper. Only several years later after the tree has died, does digging it out reveal that it was planted too deep. Roots and tree trunk tissues are adapted to being under and over the soil respectively. The reverse never works. If you see branches coming from below the soil level it’s a tell tale sign that the tree was planted too deep.

Once you have selected your tree and dug your hole its time to put it in the ground.

In the past the most nursery stock was available as bare root, for smaller trees or balled and burlapped for larger landscape feature trees. Container grown trees are a relatively new phenomenon with tremendous advantages, and one big problem. This is the phenomenon of girdling roots. Trees grown in pots will have roots that circle the margin of the pot. When you take the tree out of the pot you will see these roots at the edge of the root ball. It is advised to take a sharp knife and cut these circling roots in a few places around the root ball to limit the chance that they will grow to strangle the trunk of the tree. Girdling roots are much less of a problem with balled and burlapped trees as exposure to air will prune the roots before they get to the edge of the root ball.

Place your tree into the planting hole carefully and fill the soil back into the area surrounding the root ball. The soil should be the same as the soil surrounding the planting site. Mixing back fill soil with peat or sand is not recommended as it creates problems with root penetration beyond the planting hole as the tree grows. The trees roots may never extend past the amended soil. Do not put soil on top of the root ball, don’t bury the trunk. Once your tree is in place and has been backfilled, gently pack the soil around the root ball to eliminate air pockets. Watering after planting is essential to keep the new roots from drying out and to establish a moist link between the planting site and the ground water. If your tree is unstable it may require staking or guying. This subject will take an additional article as it is often done incorrectly. For further advice on tree planting contact an expert, an ISA Certified Arborist.

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