And the Best Time to Plant Is . . .

Planting a tree has gotten a lot easier these days, not from new technology in digging equipment but because research into trees’ responses to various planting practices has dispelled many myths. Too late to act on this one but even the best season for planting has been shifted for many tree species from the more traditional spring planting to planting in fall.

Arbovitae & Balsam fir, planted in 1990s

Okay, perhaps you haven’t come up with where or what to plant this spring, take heartwith some of the reasons why fall — if you’re ready then — is a good, in some cases better, time. Fall planting is easier because the soil is generally in better condition for digging and because planting can be done at a relaxed pace. Lingering summer heat coupled with fall rains makes for a soil that is moist and crumbly rather than the goopy mess often found in spring.

And there’s no need to rush a plant into the ground for fear of stems beginning growth before roots take hold. Buds won’t awaken until they’ve experienced a winter’s worth of cold, and by then roots of fall planted trees will have already begun to extend out into the surrounding soil.

Come spring, roots of fall planted trees are also in place and ready to soak up a winter’s worth of soil moisture, so need less watering by you.

Don’t Work So Hard

Whether painting in spring or fall, DO NOT bow to certain traditions of planting. Such as: The old saw that it’s better to put a five dollar tree into a fifty dollar hole than a fifty dollar tree into a five dollar hole (in each case the number referring to size) is another tree planting myth that has been laid to rest.

New research shows that tree roots establish most quickly in a planting hole only two to three times the diameter of the root ball and no deeper than necessary for the plant to stand at the same level as it did in the nursery. Or higher, if a mound is needed for improved drainage.

And if the tree is bare root with a couple of extra long, errant roots, just take your pruning shears and shorten them.

The shallow hole is needed so the plant can sit on a firm base of undisturbed soil that won’t settle with time. 

And rather than digging full depth right out to the edge of a planting hole, taper its depth from ground level at the edges to full depth at the center, creating a cone shape. This opens the way for new roots, most of which grow horizontally and near the surface. When you finish, rough up the inside of the hole to break up any glazing from your shovel blade that might slow root penetration.

Drainage

The recommendation to improve drainage by dumping gravel or some other coarse material into the bottom of the planting hole is another misguided, dated notion. The thought was that gravel or some other loose material would help drain away water.

What really happens is just the opposite. A so-called “perched” water table forms above the layer of gravel and water does not drain from it until the upper layer becomes saturated. (See my book THE EVER CURIOUS GARDENER for a more in-depth explanation of this phenomena.)

Yet another myth that can now be put to rest is to mix plenty of compost or other organic materials into the soil from the planting hole to create a fluffy, rich substrate for the developing roots. If you were a young root growing in such a place, would you ever want to leave? No. In such a hole, roots grow round and round just as if they were confined in a pot, the plant eventually strangling itself.

Also, organic materials decompose turning mostly to carbon dioxide and water, but also releasing plant nutrients; but, with that evanescence of organic materials, the tree sinks. The place for compost and other organic materials is near and on the surface of the ground, where soil has the highest biological activity and the bulk of tree feeder roots grow.

Less is More

No need to do a whole lot of work with your pruning tools either. Myth held that the tops of newly planted trees needed to be cut back in order to balance the loss of roots that occurred during transplanting. But many trees today are sold growing in containers, so lose no roots at at all when transplanted.

And more important for every kind of nursery tree is that the buds on stems, especially those near the tips, produce hormones that stimulate root growth. Limit any pruning to total removal of a few stems rather than lopping back many stems.

Only two situations warrant pruning tree stems — other than stems that are damaged, dead, or grossly misplaced — at planting time. The first is if a site is very windy, windy enough to sail an as yet unrooted plant out of the soil. The second is if the season is very dry and the plant will not be watered. Any tree, of course, grows best with timely watering throughout its first, perhaps its second, growing season.

Stake It Out, Or Not

Once a tree is in the ground, staking is the traditional next order of business — and it’s another practice needing reconsideration. Generally, don’t stake a tree unless it can’t support itself (sometimes the case with trees from closely spaced nursery rows), if movement of the trunk causes the root ball to rock, or if wind might uproot the whole plant. In the latter case, judicious stem pruning, as mentioned above, might offer less of a “sail.”

Support for any young tree should let the top move freely and allow for some movement of the trunk, all without causing abrasion where the tie or ties make contact. Movement thickens the trunk, making it stronger.

Allow the top to move by not restraining the tree more than two-thirds its height. Also, use an elastic tying material, such as the inner tube of a bicycle tire, to allow movement at and below the point of attachment while keeping a firm enough hold on the trunk to avoid abrasion.

A single tie to a stake is often sufficient and has the advantage of allowing some trunk movement below the tie, lessening stress at the tie and helping to strengthen the whole trunk. Larger trees might require two or three stakes, or guy wires. 

Even when staking is necessary, the sooner the stake or stakes are removed the sooner the plant can develop a strong trunk and root system. With most small trees, remove stakes after one year; larger trees might require stakes left in place for two years.

And finally, don’t turn your back on a newly planted tree once it’s in the ground. Mostly what’s needed is regular watering, more for larger trees. Not turning your back doesn’t counter any myth; it’s always been sound advice.