It is better to amend the soil with organic matter around a tree or shrub (circling the perimeter) when planting rather than improving the planting hole. Otherwise roots have no incentive to migrate, eventually encircling the planting hole, known as root girdling (image courtesy: www.henderson.ces.ncsu.edu).
By: John Green, Certified Texas Expert Gardener, Orange County, TX
Most parts of SETX received much-needed rain last week, but the totals weren’t enough to end the drought and more is needed. Noticeably, day and evening temperatures are trending lower, meaning fall has arrived! As a reminder, it is time to relocate tropical and sensitive plants to protected environments before nighttime temps fall below 50F which can damage plants. Fall is the perfect time to plant trees and shrubs.
Planning is the first step…before digging holes! It is imperative to call the National “call-before–you-dig” phone number (811), two to three business days before digging holes or beginning a landscape project. Calling initiates a process in which professional locators are deployed to mark the locations of underground utility (gas, electric, water, telecommunication, and pipelines) lines with flags as required by law. The service is free and helps to mitigate accidents, injuries, and service outages.
Once in-ground utility lines are flagged, walk around the area to determine the intended planting sites’ proximity to overhead utility lines, making certain not to plant trees near electric lines. Otherwise, as the tree matures, it will be trimmed (butchered) for utility company access to maintain lines above or below the tree. Trees need significant space to attain mature size and require full sun. Fall and winter are ideal seasons to plant trees. Trees are dormant which provides them time to develop a strong root system, under less stress during cooler weather, and there is increased rainfall, rather than expending twice the energy to grow leaves and roots during warmer months…this makes for a stronger tree! Follow these steps for planting a tree.
Transplanting (burlap wrapped or potted)
Timing- Plant about six weeks before the first hard frost to allow for root establishment before the ground freezes.
Spacing- The recommended space allowance for trees to reach unimpeded canopy and root maturity: small trees require at minimum (H x W) 10’ x 10’, medium trees need 20’ x 20’, and large trees need at minimum 30’ x 30’.
Watering- Water newly planted trees regularly (weekly if no rainfall) during the first two years. As a rule, trees require approximately 10 gallons of water/ rainfall per week (spring & summer) for the first two years. During the fall, a tree needs about 5 gallons supplemental water per week per inch of trunk diameter (when rainfall is not adequate).
Mulching- Apply a layer of 2 to 4-inch layer of mulch around the base of the tree to retain soil moisture and protect the roots. Ensure the mulch doesn’t touch the tree’s trunk.
Protection- Wrap the trunk to protect it from sunscald, animal damage, or string trimmer and mower damage (speaking from experience) especially in the first couple of years.
Selection- Select trees which are suitable for our climate and USDA growing zones (9a or 9b). A few recommended trees which grow well in clay soil:
- Shade: Chinkapin Oak, Bur Oak, Live Oak, Cedar Elm, and Chinese Pistache.
- Ornamental: Texas Redbud, Desert Willow, Crape Myrtle, Mexican Plum, and Texas Mountain Laurel.
- Fruit: Crab apple, Pecan, Plum, Fig, Jujube, Pear, Pomegranate, Persimmon, Mulberry, Apple, and Mayhaw.
Digging- Dig a wide, shallow hole and make the hole at minimum twice as wide as the root ball but no deeper than its height. Slope the sides of the holes to prevent root binding. Score the sides using a shovel to make vertical cuts or slices in the sides of the hole to allow the roots the opportunity to better penetrate our compacted clay soil.
Positioning- Place the tree into the hole so the top of the root ball is slightly above the original soil line, since planting too deeply will lead to root rot.
Loosening- Gently loosen the roots from the root ball. It is important to gently disentangle roots which are circling the root ball. Tease them apart with your fingers and expand them away from the root ball to encourage them to grow outward.
Backfilling- Use the excavated (native) soil removed while digging the hole, mixing in small amounts of compost and composted manure to improve soil structure. Steer clear of using a completely different soil type which will discourage roots from spreading beyond the hole.
Transplanting (Bare root)
Editing- If the tree is a bareroot specimen remove dead, diseased, or broken roots using pruners which are sanitized with isopropyl alcohol between each cut.
Soaking- If the roots are dry, then soak them for several hours or overnight in lukewarm water before planting. Placing an air stone (aquarium bubbler) will increase the supply of oxygen to the roots as they are soaking.
Trees require space to grow for both their canopy and roots to spread. Not all tree roots grow straight down. Trees have fine roots which spread out from the main taproot near the soil surface. These roots are for nutrient and water uptake which is the reason trees should not be surrounded by hard surfaces such as concrete which stresses tree root systems, often leading to its demise! Compacting the soil nearby trees also not recommended, which might lead to the same outcome due to root damage.
Planting Technique
Mix half of the excavated soil from hole with compost and composted manure, mixing half soil and half amendments. Place a portion of the mix in the bottom of the hole and then place the tree into the hole. If potted, cut through the pot carefully (without damaging roots or cutting into the root ball). If the roots are compacted or encircling the root ball, gently loosen some of them and remove a portion of the soil from around the trunk to ensure roots are not “girdling” the trunk. Remove roots girdling the trunk as they will eventually strangle the tree.
Bareroot and burlap wrapped trees might have “J-shaped” roots. It is important to straighten them, if possible, when planting. This is a cultivation technique used when growers plant specimens in fields.
Begin filling the hole and alternating the soil mix and the native soil. The tree will receive the benefit of nutrients from the amendments while adapting to the native soil. Lightly tamp the soil to firm but not compact it while filling the hole. There will most likely be soil remaining. Utilize the remaining soil to build a 4-inch berm around the perimeter of the hole. Fill the basin (berm) with water to soak into the ground, until water reaches the root ball.
For the first week after planting, lightly water the tree with about a quart of water, daily. The second week, it increases to one or two quarts of water every other day. The third week, water with two to three quarts every third day. The fourth week and on water as needed. The goal is to cut back on watering so the root system becomes strong enough that the tree will thrive on natural rainfall.
Fertilization is not necessary. Most trees do not need support by staking, though it can provide stability and support for the 1st year while roots are growing. Add a 2 to 4-inch layer of mulch (shredded bark or compost) to retain moisture and minimize weed growth.
Common Mistakes
Avoid- Adding gravel to the bottom of the hole as this can create a “bathtub effect” which worsens drainage by causing water to pool above the gravel layer.
Amendments- Adding too much or the wrong type of amendments will create a “pot” effect, which discourages roots from growing into the surrounding soil.
Watering- Water wisely and deeply but infrequently since clay soil retains moisture.
Until next week fellow gardeners, let’s go out and grow ourselves a greener, more sustainable world, one tree at a time! Gardening questions answered: jongreene57@gmail.com.
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