It’s spring. Perennials are emerging from underground. Spring bulbs are in bloom. The buds on are bare branches are bursting into leaves. Except for those that aren’t. A look around indicates that a lot of my neighborhood trees didn’t survive the winter.
Trees are not cheap. There is a significant cost when it comes to purchasing and planting a tree, especially one large enough to satisfy the HOA. It’s easy to blame their subsequent demise on Colorado’s notoriously capricious weather. Easy, but you’d be wrong. By far, the primary reason our new neighborhood’s trees don’t survive is improper planting.
It’s not the weather that’s killing the trees. It’s us.
The mistakes homeowners make tend to cluster around six issues: uncorrected root problems, planting too deeply, mulch volcanoes, improper staking, misdirected water, and post-planting girding. There’s one more mistake more commonly made by commercial landscapers. I’ll address the first two today, and the others in the following months.
Plants grown in round pots (or held too long in pots that are too small) tend to have circling roots. Instead of pointing outward like spokes of a wheel, they follow the curve around and around the inside of the container. Moving them to a larger pot doesn’t change the direction of the existing roots. And when we buy those plants and stick them in the ground, the roots continue as they grew, never leaving the planting hole. Worse, as the trunk expands, it eventually fills the space inside that circling root. It can’t grow any further. The truck becomes girded, and the tree dies.
There’s a simple solution: root washing. When you bring home a newly purchased woody shrub or tree, remove the burlap and wire basket or knock the plant out of its pot. Then, take a hose and wash the dirt off the roots. Most of the weight is in the (typically clay) soil, and washing it all off will make the tree much easier to handle.
Let me repeat this—you need to remove that burlap and cage. I know that many knowledgeable landscapers insist that it’s fine to leave them in place—the burlap will decompose and the roots will simply grow through the metal basket. However, our cold and dry conditions here in Colorado aren’t favorable for decomposition. There’s a good chance that burlap will still be intact years from now, with most of the tree’s roots still confined inside. Furthermore, any burlap that sticks out of the soil will encounter our drying winds, wicking moisture away from the roots—a likely case if the tree is planted at the proper depth (as in this photo). And, of course, you can’t wash the roots if there’s burlap in the way.
Once you’ve removed all the soil, look at the roots. You may be surprised by what you find. If needed, grab a pair of pruning shears and correct any structural problems. Then proceed as with any bare-root purchase. Dig a shallow hole (more about that in a moment) large enough to spread the roots so they point outward. Then fill in the hole with the same unamended soil you dug out of it. Now the roots will expand into the surrounding area and the plant will flourish.
At the same time, you can also check to see if the plant was inserted into the soil to the proper depth. Frequently, as a tree grows in a wholesale nursery, it ends up being buried deeper and deeper in each succeeding pot. While the directions may tell you to “plant at the same depth at which it was grown,” doing so may condemn the tree. Instead, only dig the planting hole as deep as needed to support the tree so that the root flare is visible above ground. The root flare is where the trunk starts to expand into the root system. You can easily see the root flare on this mature tree:
Burying the tree any deeper causes two issues. With few exceptions, the vast majority of roots grow in the top 18 to 24 inches of soil. There just isn’t enough air and water below that level. Piling too much soil on top suffocates those roots and kills the tree.
As you remove the soil around the root ball, you may discover another ring of roots higher up on the trunk, but still below the soil level. Sometimes the tree tries a last, valiant attempt at rescuing itself by growing a new set of roots at a more appropriate soil depth. However, those adventitious roots are rarely enough to save the tree, and just prolong the inevitable. If you see them, trim them off, then plant the tree properly. It’s easy—just remember that deep burial is for corpses, not living trees.
The second problem is that burying the trunk puts various soil microbes in contact with to the bark. Eventually, it rots away, which (you guessed it) kills the tree.
While this is not news, it’s incredible how many landscapers have no clue about proper planting depth. A recent walk down our street revealed that the majority of newly planting trees were buried far too deeply! They’re easy to spot—the trunk looks like a pole emerging from the soil, as shown here. Pete and I had to dig up and re-plant a number of our trees after our landscaper was done. One hawthorn in particular had been planted 18 inches too deep! Thankfully, we got to it in time.
Sadly, hiring a “professional” is no guarantee that your trees will be planted correctly. It’s up to us, the ones paying for the trees, to ensure they get off to the best start possible.