So You Think You Know How to Plant a Tree?

September 16th, 2004

   Planting a new tree or shrub isn’t as simple as it seems.

   Even the experts don’t all agree on the details. And what’s “right” or “wrong” has changed markedly over the years. That ought to tell you something right there.

   What’s more certain is that the more little factors you mess up, the more likely you’ll be doing it all over again.

   So to help minimize the carnage from this year’s fall planting, here’s the system that works for me.

   Your mission begins by picking healthy plants in the first place.

   Don’t doom yourself right off the bat by unwittingly buying plants with rotted, overwatered roots or ones that have been sitting around all summer with little care.

   Gently slip your prospective purchases out of their containers and look at the root system.

   You should see a generous amount of white or tan roots. Black, slimy ones or brown, shriveled-up ones are bad news. Pass on those.

   A dense mass of circling, tangled roots isn’t ideal either, but at least those roots are alive and fixable.

   I’d also much rather buy a small plant with a big root system than a big plant with a little root system.

   In general, smaller trees and shrubs transplant easier and are more forgiving during that critical 1- to 3-year adjustment period in your garden. Small ones are cheaper and easier to handle, too, and within a few years, they’ve usually caught up size-wise to bigger transplants.

   If your new trees and shrubs will be sticking out the window or will be hauled home in a pickup, be sure to cover the foliage with burlap, tarp or a similar covering. It’s incredible how much moisture a 55-mph highway wind can suck out of unprotected tree leaves.

   Next up is soil preparation. If you’re lucky enough to have fairly decent soil, just loosen it and plant without adding anything.

   Unfortunately, most people in new developments have “soil” that’s more akin to the driveway. Grading usually lets behind compacted subsoil topped by maybe 6 inches of “topsoil” — the piled-up shale and clay that was scraped off in the first place, then left to sit and collect weed seeds. That lifeless result is a death trap for plants.

   It’s best to prepare whole planting beds by loosening the soil a foot deep and tilling about 2 inches of organic matter into the native soil. That’ll give you slightly raised beds that will help drainage and give your roots free reign to spread out in all directions.

   But if you’re planting only one tree or shrub in a hole, loosen the soil only as deep as the root ball but three to five times the width of the rootball. (Or dig the hole so you’ll have a minimum 2-foot border of loosened soil around the planted rootball.)

   Add no more than 10 percent organic matter to these holes. One of the quickest ways to kill a new tree is to plant it in immaculate planting mixes that are scarcely wider than the root ball. Water will back up into the hole once it hits the surrounding clay mess and rot the roots.

Drop type spreader.

   Fertilizing is one of the most overrated factors at planting time.

   Research has shown that phosphorus and other root-stimulating fertilizers have little, if any, effect on growth, and they don’t increase survival rates.

   “Applying fertilizer ‘to be safe’ without knowing if mineral elements are deficient wastes time and money,” said Dr. Jeff Iles, an Iowa State University horticulture professor.  “The bottom line is that fertilization will not make up for poor post-planting care or mistakes made during installation.”

   If you really feel the need to add something other than organic matter, consider mychorrizal fungi. These beneficial fungi grow on plant roots and help them take up more moisture and nutrients. There’s some evidence they’re of marginal help. Sometimes.

   If a soil test indicates your soil needs a particular nutrient, by all means add it. Just be sure to thoroughly mix any amendment throughout the native soil as opposed to adding it in a layer.

   Also of no help is the old advice about pruning off some of the plant’s branches to make up for the loss of roots during the transplanting of field-grown plants. Research found that only takes away leaves that otherwise would manufacture sugars that the roots need to develop.

   At planting, only prune off dead, broken or seriously deformed branches.

   Now here’s the biggie — planting at the correct depth.

   Eric Vorodi, a certified arborist and owner of About Trees Consulting, a Boiling Spring tree-consulting business, says planting too deeply is by far the No. 1 planting miscue.

   That rots roots, rots bark and deprives the roots of adequate oxygen while often leading to a long, slow, struggling plant death, he says.

   Some people intentionally plant below the soil surface, figuring that will encourage better roots (wrong) or stabilize the plant better.

   Others plant at grade, but the tree or shrub gradually sinks below grade as loosened soil settles. (That’s why the soil should not be loosened any deeper than the depth of the rootball.)

   But Vorodi says a subtler and equally threatening problem is when a new plant already is buried too deeply in the container or burlap-covered ball.

   The only way to head that off, he says, is to identify the “root flare.”

   Look at the base of the main stem. You should see the stem swell or flare out where the stem meets the roots. If you don’t see that, gently remove soil until the flare is exposed. Then plant so that this root flare is at or just above grade.

   Some arborists are even recommending that all soil should be routinely removed from rootballs by soaking them in water. With the soil off, the root flare can be determined. Then plant immediately with the flare slightly above grade using soil native to the planting site.

   Don’t be fooled by occasional “adventitious” roots that have sprouted from the trunk above the flare. Look for the flare and gauge planting depth by that.

   “Virtually nobody — homeowners or professionals — identifies the root flare on the tree before digging the hole,” Vorodi says. “This one practice would essentially solve all planting depth problems.”

   In container grown plants, be sure to fray out any circling roots before planting. If you can’t free them with your fingers, it’s better to make a few cuts in the tangle so the roots don’t continue growing in a tight mat, thereby stunting the plant’s growth.

   Situate the plant in the hole so it’s straight and oriented with the “good side” where you want it.

   With a balled-and-burlapped plant, cut away wire baskets, rope and burlap once the plant is settled in the hole.

   However, if the root ball isn’t solid enough to hold together without these supports, wait until you’ve backfilled partway with soil to try removing them. It’s best to remove whatever you can of these materials, but not at the expense of having big clods of soil fall off, tearing roots along with them.

   At the very least, though, remove rope from around the trunk and cut the tops off of burlap and wire baskets so nothing is exposed above-ground after planting.

   After you’ve backfilled the soil about halfway, tamp it down and soak with water. Wait for the water to drain, then backfill the rest of the way, tamp and water again.

   Make a little ridge around the perimeter of the hole out of soil and/or mulch. This will help contain water in the root zone.

   Cover the hole’s entire surface with 2 to 3 inches of bark mulch to prevent weeds and retain moisture. Keep the mulch a few inches back away from the plant’s trunk or main stems so the mulch doesn’t rot the bark.

   And that’s it. It may not be simple, but at least you’ve maximized your new tree’s survival odds.

   Until the deer find it. 

   To stake or not to stake? That is the question.

   The answer is that it’s best not to stake a new tree unless it’s top-heavy or in a windy area where it’s likely to blow over.

   Research has found that roots develop best when a tree’s top growth is allowed to sway in the wind. It’s one of those adversity-breeds-strength things.

   If you have to stake to avoid leaning or blow-overs, use two 2-by-2-inch, 8-foot-tall stakes driven into the planting hole at right angles to the prevailing wind direction. (Drive the stakes beside, not into, the rootball).

   Fasten the trunk with rope fed through a piece of cut-off hose or use straps or other wide, elastic material. Don’t wrap wire or narrow rope directly around trunks because these materials can dig into and damage the bark.

   Secure tightly enough that the tree won’t blow over but not so tightly that it can’t sway at all.

   Attach staking at the first set of branches and remove it after no more than one full year.

   After planting, the most critical job is keeping the soil consistently damp but not soggy.

   It’s best to water slowly and deeply until the soil is damp both below and around the new rootball. You may need to water every 5 to 7 days the remainder of the fall if rain doesn’t do the deed for you.

   The best water gauge is your index finger. Stick it in the ground a few inches to determine if it’s time to water or not.

   A good rule of thumb on quantity is to apply 1 to 2 gallons of water for every inch of the trunk’s circumference near ground level.

   Another guide is to apply 1 gallon of water for every square foot of surface area of the planting bed.