By Paul James
Back in the mid 90s, researchers proposed a new way of planting trees that involved digging a wide, shallow, saucer-shaped planting hole that measured five times the diameter of the tree’s root ball. The idea was that roots would grow more rapidly in the monstrous planting hole, thereby enabling the tree to become established faster. Lots of so-called experts immediately jumped on the bandwagon and praised it as the most important revelation in tree planting since the invention of the shovel. But the question is, Does it really work?
Well, I’m not saying that it doesn’t work. I planted a Shumard oak using that method back in 1996, and it’s doing great. The root ball of the tree was three-feet wide, so I wound up digging a 15-foot diameter planting hole roughly two-feet deep at the center, which took me an entire day. However, I also planted three other trees that same week using a more traditional approach (more on that in a moment) and they’re doing great too.
So what I am saying is that the “new” way of planting a tree is just too much work! And more to the point, it isn’t even necessary!
What then, is the best way to plant a tree? In truth, the planting hole only needs to be a foot or so wider than the root ball. One of the biggest advantages to keeping the hole relatively small (aside from the fact that it’s a much, much easier task) is that the tree will be well anchored in the hole from the start. The more important thing to consider is the planting depth. Keep this thought in mind: You’re planting a tree, not burying it. If a tree is planted too deeply it’ll likely die. That’s why you should always plant a tree above grade, and how much above grade depends on your soil type.
In heavy clay soil (Hello, Broken Arrow and Owasso!) you should leave as much as a third of the root ball above grade. Clay soil holds water, and most trees don’t like wet feet, so planting above grade keeps roots from drowning. In sandy soil (Howdy, Bixby!) you should do likewise because the tree will settle in the soft sand. In most other areas of Green Country, you should leave approximately four to six inches of the root ball above grade.
Adding soil amendments such as compost to the planting hole is rarely necessary, and can actually cause more harm than good because roots will remain in the area of amended soil rather than reach out to the native soil. It’s best to simply let the tree adapt to your native soil. In extremely heavy clay or super sandy soil, it’s okay to amend the soil somewhat, but don’t add more than 25% to the native soil used to backfill the hole. Adding a root stimulator at planting time is a good idea, and a two- to four-inch layer of mulch is a must.
And finally, a word on staking. Unless you live in an open area where the winds come sweeping down the plains, or you’re planting a bare-root tree, staking isn’t necessary. In fact, letting the tree sway in the wind without stakes will result in a stronger trunk.
So grab a shovel and plant a tree. And feel free to thank me later for saving you from hours of unnecessary digging.