The Art of Digging a Hole for a Tree

…and fill it up again with a newly planted tree

Learn how to dig a proper hole for your tree or shrub.

Every good garden book and article that gives advice on how to plant a shrub or tree will tell you to dig a large enough hole to give the tree a good start. I’ll tell you that in numerous places in the plant posts that I write, but often the fine points of digging a hole are overlooked.

It is probably just abridging the information, but there is the inkling of a thought that perhaps, just maybe, the act of digging a hole is beneath us, like the old disrespect for ditch diggers. And over time we might have misinterpreted the admonitions (“Do you want to dig ditches all your life?“) as disrespect. After all, there is nothing wrong with honest work, but there is an understanding of how hard such work might be. Most of us want to avoid the back-breaking kind.

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So in the interest of the tree’s future and that of the health of your back, I offer to you this seemingly elementary set of tips on how to dig a hole.

The most important part of your new tree is the root ball. Believe that. The tree will go nowhere, let alone look beautiful, without a healthy start in the root structure. Much of the advice on how to plant your tree revolves around the most advantageous set of conditions for the roots to grow easily, and to become accommodated to their new home, the earth of your garden.

Recommended Shovel For The Job

A long handled round point shovel with heel plates.

The tool I use for this job

I always used a full sized round point shovel– the kind builders use. Recommended as one of the main basic tools to start out with in a garden. And it is this job for which it is so useful.

How To Dig A Hole Big Enough

The first bit of advice has to do with size. Of course, it does.
Dig a ten dollar hole for a one dollar plant That is, the hole for the rootball should be much bigger than what you can barely squeeze it into. The hole should be generous, and that requires a little initial work, but look at it this way: the tree was one that you wanted very much to grow in your garden, it probably cost more than other plants that you purchased for your property, it will likely outlast you in longevity and become quite large and valuable in time. All reasons to give it the effort and time to plant it right. A very nice large hole for its roots.

This planting hole is not big enough.IMO

How To Dig Loose Enough

That is, the dirt surrounding the roots should be loose enough to allow for ease of …what else? taking root. If you have clay ground, like the kind I have gardened on in Central Ohio, then you should pay attention to those sculpted sides of the freshly dug hole. Those are not desirable. Sometimes the pressure of the shovel will compact the earth until you have something like a hollowed out bowl. Simply take the sharp edge of the shovel and chip into the sides to rough it and create horizontal fissures. Only a few authors have instructed me on that. But I think it s a benefit to the tree and allows for water to escape the “bowl of clay”.

Some science says don’t add amendments to the trees hole, but I have always had good results from doing so, and it helps keep the soil around the new roots looser and more amenable to growth if there is humus in the form of compost or peat moss. I chop it into the soil with the shovel, mixing a bit at the bottom of the planting hole and more as the original soil is filled in around the newly planted tree. The reasoning for not adding amendments is that the practice could lead to the collar of the tree sinking too low, and a leaning growth pattern. Arizona edu. had this to say:

The purpose of loosening the soil in a wide planting hole is to minimize resistance that growing roots encounter in compacted soil and to ensure that oxygen and water are readily available in the root zone. The purpose of planting a root ball on undisturbed soil is to prevent the root collar from sinking below the surface when loosened soil settles.

All the expertise is on the side of digging a large planting hole, but no amendments; the more important factor was regular water during dry periods.

University of Massachusetts Extension says:

…it is now recommended that the planting area be loosened and aerated at least three to five times the diameter of the rootball …the planting hole be dug no deeper than the rootball as measured from the trunk flare to the bottom of the ball.

Serious problems can develop from the rootball being planting either too deep or too high; I’ve seen plenty of problems from plants being planted too high.

The same source said: “The addition of an organic soil amendment may be called for if the existing soil is of poor quality, such as excessively sandy or heavy clay soils or those consisting of undesirable fill material.” And that returns us to what I found from my own experience. Having gardened on heavy clay, the addition of some compost and peat moss has been helpful, and perhaps my amounts were not so generous as to make it a problem. “A little dab’ll do ya'”, or “moderation in all things”, applies to adding compost to the tree planting hole.

About that “trunk flareThe flare is the spreading trunk base that connects with the roots. “. Covering it is what causes a number of growth problems for a tree, and it should be said here that includes the practice of mounding huge amounts of mulch against the trunk of the tree. Please don’t do that.

Good tree planting instructions

The Method

When you dig a hole, wear shoes. I had to say that- because you might be sixteen years old and think your feet are made of iron. A shoe that protects your arch is probably a good idea, too. It is tempting to want to exert force by driving your foot onto the lip of the shovel, but that is not going to get you far… push down with your foot and rock the shovel, then push down again, etc. until you cut through the dirt.

Dig a hole for a shrub

Go to a reasonable depth. If your shovel gets stuck, and you are determined enough to lever it up, and strong enough (or rambunctious enough) to give lift to the shovel in hard resistant clay the full length of the shovel blade… well, something has to give, if the soil won’t.

A wooden shovel handle can break.

At least that is the explanation I have for how my teenage boys were able to break the perfectly sound ash handles on my shovels. It is hard on your back to do it that way, anyway. Save your back and patiently push down, rock, and lift the dirt out of the hole. Besides, many of the shovels come with fiberglass handles, now…

Before you place the tree in the hole

Did you water the tree in its container or soak the balled and burlapped rootball well? Did you cut away any plastic string or wrap and dispose of them? Did you remove any top part of a peat container and slice it down the sides? Peat containers left above the soil level will wick the moisture into oblivion. Dried out roots=dead tree.

How To Mud the Back-fill

The back-fill is the dirt you return to the planting hole. Be sure that you water it enough to turn it to a muddy slush. That way it will settle correctly and there won’t be any root drying air pockets.

Remember the fact that new roots like moist (not soggy) soil.

The mudding in is only for the initial planting procedure, not as a full time soaking. Roots can drown without sufficient air, the mudding just takes care that they don’t dry out with air spaces that are too large from the digging disturbance of the soil. The slurry fills in air pockets.

You have completed the art of digging the planting hole and returning it, with its new tree, to its improved condition. You’re a master, now. Congratulations… and I mean that.

* additional info on garden tools for beginners.