An article entitled “Why You Should Plant Trees in Square Holes” on the website of The Guardian says this:

“Here’s what happens to the tree’s roots when you plant them in a round hole, especially one filled with lots of rich compost and fertilizer, as the old guide books suggest. The little sapling will rapidly start growing new roots that will spread out into the rich, fluffy growing media, giving you excellent early success. However, once they hit the comparatively poorer and compacted soil at the perimeter of the hole, the roots will react by snaking along the hole’s edge in search of more ideal growing conditions.

“Eventually, this spiraling action around the limits of the hole will create a circular root system, with the plants essentially acting much as they do when grown in a container.”

I don’t want to hurt anyone’s feelings, but that’s silly. Tree roots are not intimidated by poor, compacted soil. I’ve seen, as we all have, tree roots muscle their way through asphalt and concrete.

Many websites now preach square-hole planting. Here is a quote from an article entitled “Planting Trees In Square Holes Makes Them Grow Stronger And Faster” that was published on the Intelligent Living website in 2019:

“The roots won’t develop a circular root system because, as systematic planting trials have shown, the roots are not good at growing around corners. When the roots hit the 90-degree angle of a square hole, rather than snaking around to create a spiral, they spread out of the planting hole to colonize the surrounding native soil.”

Really? Tree roots are not good at growing around corners? And only upon hitting the 90-degree angle of a square hole’s corner will they spread out to colonize the surrounding native soil?

How is the angle at the corner of a square any different from the angle the roots would have to turn to get to that corner? I feel a need to repeat the word silly. Tree roots are not deflected nor deterred by earthen boundaries, round or square.

The Intelligent Living article refers to systematic planting trials that prove square holes are better. What trials? Why didn’t they provide references to a few to back up their article?

I went in search of planting trials that tested the shape of holes, and managed to find only one. It is entitled “Effects Of Planting Hole Configuration And Soil Type On Transplant Establishment of Container-Grown Live Oak,” published in the Journal of Arboriculture in 1995. The paper concludes that the shape of the holes  (cylinder, cube, or star-shaped) had no effect on the growth of the trees. They grew equally well from any of the shapes.

Throughout the world, millions of saplings have been planted in round holes, and there is no evidence they were inhibited or became root bound as a result. Dig a square hole if you want to, but don’t believe articles on the Internet that claim doing so will make a difference in the health of a tree.

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