Myth #1 – Trees have deep roots.
When you see a giant tree in the forest you just assume it must be anchored in by one long, deep root. However, since most of the moisture and nutrients are found on the forest floor that is where most of the roots are as well. Trees have tap roots that spread laterally. Ninety-five percent of a tree’s roots are in the top three feet (one meter) and most of the fine feeder roots are in the top six inches (15 cm). When planting a tree take this into consideration and loosen the soil wide rather than just deep.
Myth #2 – When Planting a Tree Amend the Hole with Nutrient Rich Soil
Filling a hole with nutrient rich soil is akin to handing a child a bowl of candy and then scattering fresh vegetables and fruit several feet away. The child will have no incentive to get out of the chair to seek out the vegetables and fruit if there is a bowl of candy right in his lap. Once the bowl is empty the child will likely just sit in the chair circling their hand around the empty bowl waiting for more candy to appear, rather than getting up and going in search of the outlying natural nutrients.
Wow. Okay, even I admit that’s kind of a weird analogy.
Nonetheless the premise holds true for trees. Filling a hole with loose, friable, compost only encourages the roots to stay put and circle around and around the hole where life is easy until they run out of both space and food.
Planting in the same soil that surrounds the tree is tough love at its best. The tree will then send out roots far and wide to search for nutrients and moisture the way trees have done for millennia. If you must amend keep the ratio to ninety percent existing soil and ten percent amendments.
The only exception would be if the entire area for 50 feet (15 meters) around was also amended and rich, in which case the tree will no doubt thrive beyond belief.
Myth # 3 – Tree roots can be found right out to the drip line (drip line meaning where the outer canopy of leaves drip after a rainfall…in other words not just tight to the trunk).
Mature tree roots actually extend two to four times beyond the drip line. In fact, over 60 percent of a tree’s roots can be found in this outlying area. So if you have to water large established trees, water widely rather than next to the trunk. Exceptions would be new trees that are just starting to spread their roots.
Myth #4 – Mulch around trees with bark or compost to add curb appeal, conserve moisture, protect from mowers or to extend flower beds.
While mulching does do all the things listed above, it can also be the death knell for your tree if done improperly. Anything more than four inches (10 cm) will suffocate the feeder roots and can cause crown rot if piled too thickly against the base of the tree. Mulch can also attract rodents which will quickly girdle a tree (chewing the bark around the base) leading to its demise. The tree’s not the rodent’s. Keep mulch well away from the tree’s trunk.
Myth #5 – Young trees should be staked and tied tightly so they grow straight and strong.
Once again, tough love rules. Staking a tree prevents it from swaying in the wind, an action that builds tree muscle…a process dubbed Thigmomorphogenesis by the botanical crowd (try to remember that word the next time you’re hanging out with the green thumb crowd…or playing scrabble). Coddle your tree and it will simply become reliant on the stake to hold it up. Plus it looks awful and you are no doubt humiliating the poor little guy in front of his peers.