Planting Trees and Shrubs
Text & Photo by Neil Soderstrom

The act of planting a tree or shrub is highly unnatural. In nature, these plants are never uprooted and plunked down in a new place. Root loss and new surroundings make it challenging for any transplant to survive.

Although planting techniques of decades past can work pretty well, newer techniques give trees and shrubs better chances of thriving. These include (1) planting in appropriate seasons; (2) shopping wisely; (3) digging planting holes wider; (4) positioning plants at critical depth; (5) backfilling with unamended soil; (6) staking less tightly, if at all; (7) mulching more like Nature does; and (8) follow-up testing of soil moisture.

Best Seasons for Planting
Plant either in fall or spring. This gives woody plants a chance to regenerate some roots before demands for moisture increase.

Fall. Most trees and shrubs should be planted in fall. Lee Reich, PhD in horticulture and author of Weedless Gardening, suggests these advantages of fall planting: (1) Trees and shrubs are going dormant and so don't need much water—especially true for trees that have shed their leaves. (2) Fall soil remains warmer than the air, allowing fine root hairs to begin regenerating before the soil gets too cold and thus giving the root system a head start in spring. (3) Stems don't grow in fall, so you don't need to rush the plant into soil as you do in spring. (4) Fall soil is usually in better condition for digging. Note: It's important to apply mulch over the roots to insulate them and retard the soil's freezing as long as possible so roots can take up moisture and continue regenerating. If you plant conifers, be sure their root balls are sufficiently moist as they head into winter; this will help prevent excessive drying of their evergreen leaves. Also, because many conifers are susceptible to drying in winter winds, they may need protective screening, which can also conceal them from winter-hungry deer.

Spring. Broad-leaved evergreens, such as rhododendrons and hollies, do better when planted in early spring, when root growth can precede leaf and flower growth by a few weeks. Spring is also the best for species sold bare-root. Conifers available bare-root in spring include fir, hemlock, larch, cypress, and ginkgo. Broad-leaved deciduous trees available bare-root in spring include beech, birch, cherry, dogwood, holly, magnolia, plum, sourwood, and willow, among others.

Shopping
Let's assume the following of your local nursery or garden center:

• That bare-root plants were promptly attended to upon arrival, either by placement in soil containers or "heeled in"— temporarily placed in moist garden soil in a cool shaded location to hold back top growth until permanent planting.
• That container plants, at the grower's and the nursery, were repotted as the roots grew, allowing the roots unimpeded growth.
• That balled-and-burlapped root balls, upon arrival, were mounded with insulating and moisture-retaining wood chips or sawdust. And that the rootballs were watered as needed to keep the soil moist, especially the outer six inches, with the result that the burlap remains tight against the soil with no air pockets that let roots dry and die there.

Plant Size. Are bigger plants better buys? Usually not, unless you need to make a large visual statement the first year or two. Studies show that roots of smaller plants grow at the same linear rate as those of larger plants of the same species. When smaller trees and shrubs are planted with larger of the same species, the smaller usually catch up with and surpass the size of the larger ones in four to five years. Also, larger plants will need more years of watering before replacing their roots' former outreach.

Conditions above the Root Ball. Avoid plants with dry or broken branches, suggesting inadequate watering and rough handling. Ensure that leaves look healthy, rather than withered or drooping. In fall, after leaf drop, deciduous plants should have stout, healthy looking twigs. On deciduous trees, generous branch spacing is a plus.

On tree trunks, check for sunscald, which occurs on the south and southwestern sides. In summer, sunscald results from overheated bark that dries and withers, usually damaging underlying tissues that transport water and nutrients. In winter, sunscald occurs when sun-warmed bark thaws, making it vulnerable to sudden freezing and therefore splitting when the sun goes down.

Be especially wary of plants that are on sale when their healthier-looking, less-stressed siblings are not.

Condition of Roots. If allowed to grow from seed, trees and shrubs will have about the same amount of mass below ground as aboveground. But roots don't grow in mirror image to the aboveground plant. Although

varying somewhat among species, most of the root mass grows in the upper six inches of soil and usually extends well beyond the plant's drip line (the outermost branches).

Container Plants. Ideally, these will have spent their entire life in containers, whether started from seed or from cuttings, and will have been repotted into increasingly larger containers as the roots needed room. If so, virtually all fine roots will be intact. But container plants that were recently inserted bare-root will have suffered fine-root loss.

Look for container size that justifies the aboveground plant. One-gallon to five-gallon containers may comfortably serve trees and shrubs one-foot to about four-feet tall. Lee Reich prefers small plants that stand no more than 1-1/2 times taller than the container and cautions about alleged "container plants" that are really recently potted bare-root plants whose roots may not be established.

• Advantages: Containers are easier to water and move without damaging roots. If their roots are well established, the plants offer excellent prospects for success.
• Disadvantages: Beware of container plants with roots that have been confined too long, circling upon themselves—rootbound—like a mass of spaghetti, rather than pointing outward like a cylindrical hair-teasing brush. Rootbound plants are often retail leftovers at discount prices. You can usually spot them without bothering to slip the rootball out of the container because roots protrude through drain holes.

Balled-and-Burlapped (B&B) Plants. These are usually four or more years old. Small B&B plants are dug from the ground by hand. Large ones are exhumed by truck-mounted hydraulic rigs that simultaneously sink huge spadelike blades around the root mass, cutting and lifting it from the earth. For the nursery trade, these large, heavy root masses are wrapped in burlap and secured at the base within a wire basket tied at the top with twine.

• Advantages: B&B plants make an immediate structural statement.
• Disadvantages: In most cases, B&B plants have suffered close to 90 percent root loss and will need at least several years to regenerate root systems extensive as they had in the field. This results in retarded growth.

Bare-Root Plants. Whether obtained locally or through the mail, these usually become available in seasons appropriate for planting, complete with planting instructions.

• Advantages: At $1-$2 each, you can acquire 100 bare-root seedlings for the price of a few larger container plants.
• Disadvantages: Bare roots are susceptible to bruising and breakage. And you may find it tricky to keep the roots ideally moist until planting. Too dry, and tender root hairs die back. Too wet for too long, they suffocate. Be sure to cleanly cut off any broken or bruised roots, because this helps stimulate root regeneration there. And then soak them in a bucket of water for about eight hours just before planting.

Planting
Hiring for Planting. If you decide to hire for planting, ask prospective contractors about their methods and review their contract, which should indicate planting standards and offer a year's warranty. Some contractors may not be aware of recent research or may not send well-trained employees. Some mistakenly plant trees too deeply; fail to remove the burlap and wire baskets on the rootball; and mound organic mulch against the trunk. Even though such methods may allow trees and shrubs to survive beyond warranty, they are likely to cause long-term problems.

Doing Your Own Planting. Again, spring and fall are the best seasons for planting, depending on species and root packaging.

• Step 1. Initially cut and remove turf in a circle about three times the diameter of the root ball. Don't toss turf back into the planting hole where it could create drainage and aeration problems.
• Step 2. When the soil is damp, but not wet, dig the hole itself about two times the diameter of the root ball but only deep enough to provide a firm undisturbed base that will support the trunk flare at ground level or, in poorly drained soils, only an inch or two above. You don't want the bark at the trunk flare to later sink into wet soil where it could rot.
• Step 3. Place the plant in the hole and double-check for correct depth. With bare-root plants, create a firm cone of supporting soil and drape the roots over it as symmetrically as possible. With B&B plants, cut away twine. Then cut away wire and burlap to the base of the root ball.
• Step 4. Backfill with unamended soil. At this time, you can broaden the hole near the surface by shoveling surface soil you were standing on into the hole, sloping the sides toward the root ball base. The resulting wider volume of loosened soil in the top six inches of soil will make it easier for roots to penetrate where most root growth occurs anyway.
• Step 5. Tamp the first shovelfuls of soil around the base of the roots until the soil supports the plant vertically. Do this without compacting the soil so much that you inhibit aeration and drainage. Water to help settle the soil around the base.
• Step 6. As you continue backfilling, water the soil periodically to wash out air pockets while also giving the roots a drink. Backfill with unamended soil to ground level without much further tamping. Note: Contrary to old tradition, research shows that woody plants usually do better in unamended soil, whether for texture or fertility. There's no need to fertilize at planting because woody plants don't respond to fertilizers for a year or more. Also, fertilizers can burn new roots. After a year or so, plants will respond to nitrogen boosts, if needed, especially in sandy soils that allow nutrients to leach out.
• Step 7. If staking seems prudent, stake somewhat low on the trunk and loosely loop fabric ties so they don't pinch the trunk, while still preventing the trunk from swaying too far in any direction. Root regeneration should allow removal of stakes within a year. Note: In the old days, most trees were automatically staked rigidly upright for years. But staking is no longer recommended unless wind, unstable soil, small rootball, or tree height would result in excessive swaying or toppling. Studies show that trees allowed to sway in the breeze develop larger root systems and stronger trunk taper.
• Step 8. After backfilling and staking, if needed, it's helpful with well-drained soil to sculpt a donut of raised soil around the root ball, creating a water-collection basin so water will sink directly into the root ball, rather than running off. Make the donut of only slightly larger diameter than the root ball.
• Step 9. For mulch, apply wood chips to about 3-inch depth but no closer than 2 inches to the trunk flare. Organic mulches help retain soil moisture, moderate soil temperature, discourage weed competition, and prevent frost heave in winter. Also, organic mulches attract earthworms like a dinner gong—the mulch being dinner. Earthworms create aerating tunnels while depositing nutrient-rich, water-soluble castings. As a rule, if earthworms are happy in your soil, your trees and shrubs will be too. Note: Wherever grass overlies your roots, it will strongly compete, thereby inhibiting root growth. Thus, it's smart to increase the mulch diameter accordingly, first removing underlying turf grass during the first year to two.
• Step 10. Fill the soil basin with water and let it settle. Thereafter, keep the soil in the root ball moist. Without regular watering at first, the root ball will continually become drier than surrounding soil because the roots are supplying water to the plant. Lee Reich recommends providing about one gallon per week per square foot area of root spread.
• Follow-Up Moisture Testing. To avoid overwatering and underwatering, you can test soil moisture with a wooden "dipstick." To do this, carve a point on a clean, dry paint-stirring stick and insert the stick along the edge of the root ball to its full depth if possible. To avoid cutting off roots, align the dipstick's width with root direction. Leave the stick in the soil for 30 minutes or so. If, upon removal, the stick looks moist throughout, the soil is moist throughout. If the stick is slippery wet, the soil is too wet for a while. Tamp the insertion hole closed.

Neil Soderstrom is a writer/photographer based in Wingdale.

Soil Drainage, Texture & Structure

It's generally a mistake to replace planting-hole soil with soil you think will serve better. That is, don't shovel rich sandy loam into a clay-lined hole or attempt to improve bottom drainage by adding a layer of gravel. Research shows that the interfaces of different soil textures prevent water from draining, thereby creating an unwanted bathtub effect that drowns roots. So it's usually better to backfill with unamended soil, though first modifying it somewhat by breaking up clumps and thereby easing penetration by root hairs.

Growing Conditions

Place plants in conditions they like. Otherwise, they'll struggle to survive or simply fail to look as good as you'd hoped.

Sunlight. Grower catalogs, plant labels, and local nursery staff can tell you a plant's sunlight preferences.

Temperature Extremes. Determine whether the plant can survive our Cold Hardiness Zone 5 temperatures of -20°F to -10°F.

Soil pH. This refers to a soil's relative acidity, which determines how well plants can utilize soil nutrients. Some woody plants prefer acid soils, some not. Soil pH can vary widely on a property if excavation has been extensive. You can buy inexpensive pH test kits or send soil samples to the Cornell Cooperative Extension by first contacting the Dutchess County Home and Farm Center in Millbrook, NY, (845) 677-8223, ext 0.

Drainage. Good drainage ensures that roots won't drown. Yet ideal soil will remain moist for some days at least after rain, long enough for roots to absorb moisture, along with water-soluble soil nutrients. Drainage is poor if water pools on the ground after rain. Absent a pooling problem, test drainage by digging a hole about eighteen inches deep and filling it halfway with water. If water drains significantly in an hour or two and disappears overnight, your drainage should be okay. To test more accurately, refill the hole. A five-inch drop per hour is rapid. A mere inch or two in ten hours is pretty slow.

Lee Reich adds that "drainage is often poor due to natural 'hardpans' in the soil (hardened soil layers) or from hardpans artificially formed by repeated tillage to the same depth. If the hardpan is thin, as from tilling, you may be able to punch through and improve the structure in a wide area around the planting hole. Otherwise, flexible drainpipe can sometimes carry water away."

Aeration. Pores in the soil allow air to enter, providing needed oxygen to roots and allowing the escape of root-generated carbon dioxide. Overwatering can waterlog the soil, reducing essential gas exchanges and thereby suffocating the roots and depriving leaves of water. Compaction, of course, also reduces aeration.

Neil Soderstrom is a gardening writer and photographer based in Wingdale, NY, also found at www.agpix.com/soderstrom.