Tree fruits can be very productive and learning to successfully grow fruit may be rewarding to gardeners. In part, success comes from understanding the specifics of your climate and conditions and in selecting the right species and varieties to grow. Some tree fruits, such as apples, pie cherries and plums, can be grown anywhere in Idaho. Others, like peaches and sweet cherries may not survive or produce in the colder climates and high elevation areas in the state. After planting the best trees, there is still much to learn about caring for fruit trees to enhance production and fruit quality. Discussions on tree care for the predominant fruit crops grown in Idaho are detailed below.
Tree Fruit Crops
Apples are among the most cold hardy tree fruits and are well adapted to many Idaho locations. Thousands of cultivars (cultivated varieties) are available and a wide selection of rootstocks makes it possible to grow the trees large or small on many different soils. In fact, perhaps your biggest challenge will be choosing which variety to grow among the more than 13,000 that have been named.
Apples grow and produce best on deep, well drained soils that are neutral to slightly acidic. Production on alkaline soils (pH above 7.0) can be difficult due to a plant disorder called iron chlorosis. Many of the soils in southeastern and southwestern Idaho are alkaline. Simple laboratory tests can help you determine whether your soil is acidic or alkaline and guide you in adjusting the pH with lime or sulfur. Apples bloom early in the spring and are sensitive to frost damage. You will find it best not to plant in a frost pocket or shady location.
When growing on their own roots, apple trees often reach 25 to 30 feet tall. Very tall trees make pest management and fruit harvesting difficult and do not fit into small yards. By grafting or budding a desirable apple variety onto different rootstocks, you can keep mature trees six feet tall or less and even grown them in large pots. In general practice, however, trees in the 10 to 12 foot tall range work best for most gardeners. Malling 9, Malling 26, and Mark are among the most popular dwarfing rootstocks. Malling 27 produces a very small tree that nearly always requires trellising or staking. Other rootstocks, such as Malling 106 and Malling 111 are available for problem soils, but do not reduce tree size much. When these rootstocks are used, growers typically insert an interstem of Malling 9 or Malling 26 to reduce tree size. Many other rootstocks are available, each with particular advantages and disadvantages. Your nursery or garden center should be able to advise you on what root stocks are available.
All apple cultivars require cross pollination to set good crops. Crab apples make good pollinators, as does Golden Delicious. For a list of apples varieties, see the list in the bulletin Growing Tree Fruits in Short-season gardens or in the University of Idaho bulletin Growing Apples.
Please note: Apricots are quarantined by the Idaho Department of Agriculture to prevent the introduction of diseases. Except for the fruit, no plant parts can be imported into Idaho from certain parts of the United States unless they have been grown in a disease-free area and are accompanied by a phytosanitary certificate. Home gardeners should generally purchase their apricot trees from nurseries in Idaho.
The hardiest apricot varieties available in the United States are, reportedly, cold hardy to between -20 and -30°F and are often recommended for USDA Zones 5-8. Varieties developed from Siberian or Mongolian parents are sometimes rated to zones 3 or 4. The trees bloom very early in the spring, making them susceptible to frost injury. Gardeners usually find it difficult to grow apricots in most parts of northern, central, and southeastern Idaho because of frequent frost injury to blossoms and occasional winter kill. Apricots have been grown commercially with limited success around Malad in southeastern Idaho and the crop does well in most parts of southwestern Idaho and around Lewiston.
Apricots are generally self-fruitful, but most experts recommend planting two varieties close together to ensure good fruit set. Varieties are commonly grafted onto apricot or ‘Lovell’ peach seedling rootstocks. The trees grow to about 20 feet tall and should bear their first crop in three to four years. Plant on well drained, light to medium-textured soil that is neutral to slightly acidic. Place the trees on slopes away from frost pockets.
Sweet Cherries are only marginally cold hardy and the buds can be injured at temperatures near -20°F. Production over the long term is challenging in northern Idaho and questionable, at best, in central and southeastern Idaho. Sweet cherries are grown commercially in the warmer parts of southwestern Idaho. The trees grow to about 25 feet tall and bear fruit about five years after planting. Most varieties require cross pollination, and you must be careful to select varieties that are cross compatible. For a list of sweet cherry varieties recommended for Idaho gardeners, click here.
Tart or pie cherries are more cold hardy than sweet cultivars, and make excellent pastries. The trees grow to about 15 feet tall and bear about three years after planting. Most tart cherries are self-fruitful, so you only need one tree or cultivar. Montmorancy does crop best when planted with another cultivar.
Please note: peaches and nectarines are quarantined by the Idaho Department of Agriculture to prevent the introduction of diseases. Except for the fruit, no plant parts can be imported into Idaho from certain places in the united States unless they have been grown in a disease-free area and are accompanied by a phytosanitary certificate. Homeowners should purchase their peach and nectarine trees at nurseries in Idaho.
Nectarines are simply fuzzless peach varieties. Mature trees grow to about 20 feet tall, but can be kept smaller with pruning and training. The trees bear fruit three to four years after planting. Peaches and nectarines are generally poorly adapted to northern, central, and eastern Idaho growing conditions. The trees are sensitive to freezing injury and can be injured or killed at temperatures around -10 to -15°F. Peaches and nectarines also bloom very early in the spring and the flowers are easily damaged by frost.
Varieties of both crops are usually grafted onto seeding rootstocks. Special rootstocks are available, but seldom necessary in Idaho. The trees are naturally small and you can control the size by careful pruning. Peaches and nectarines require well drained, light-textured soil that is neutral to slightly acid. Neither crop tolerates poorly-drained soils well and iron chlorosis develops quickly on soils with pH above 7.0.
Peaches are self-fruitful, as are most nectarines, so you only need to plant one tree or cultivar.
Two distinct types of pears varieties are available: standard and Asian. Asian pears are rounder and crisper than standard pears, and are sometimes likened to apples. Pears are less hardy than apples and can suffer freezing injury in some parts of Idaho. The buds and wood of standard pears are typically hardy to about -25°F. Standard pears are widely grown throughout Idaho, although they can be more difficult to grow in central Idaho and the colder parts of southeastern Idaho. Asian pears are less hardy than standard pears and are best suited to the warmer parts of southwestern Idaho. Pear trees grow to about 18 feet tall, but can be kept nearly any size by training and pruning. For artistic gardeners, pears can easily be trained into espaliers or other exotic shapes and can be trained to grow in a narrow wall along trellises or fences, or flat against walls. You can expect your first crop three to five years after planting. Seedling or Old Home rootstocks are commonly used.
Plant on deep, well drained soil and away from frost pockets. While pears tolerate somewhat heavier soils than most other tree fruits, poor drainage can stunt growth, reduce survival, and reduce fruit crops. Neutral to moderately acidic soils are suitable for pears.
Pears require cross pollination, so plant two cultivars close together. Seckel and Bartlett are not cross fertile and will not serve as cross pollinators for each other. Nearly all pear cultivars are susceptible to fire blight disease, particularly in humid climates. Fire blight can be a problem in Idaho, so try to select varieties resistant to the disease. Pear scab is also a problem disease in Idaho.
Please note: Plums and prunes are quarantined by the Idaho Department of Agriculture to prevent the introduction of diseases. Except for the fruit, no plant parts can be imported into Idaho unless they have been grown in a disease-free area and are accompanied by a phytosanitary certificate. Homeowners should purchase their peach and plum stocks at nurseries in Idaho.
Prunes are simply plums that develop high enough sugar concentrations in the fruit to allow the fruit to be dried without spoiling. The trees grow 10 to 20 feet tall and bear fruit three to five years after planting. Cultivars are budded onto rootstocks.
Both European and Japanese cultivars are available. Nearly all Japanese cultivars require cross pollination, as do many European cultivars. As a general rule, plant two or more cultivars close together. Plums are less hardy than apples. Japanese plums are injured at temperatures between -10 and -15 F. European plums are injured at temperatures between -15 and -20 F. Although adaptable to a wide range of soil conditions, the trees perform best on deep, well drained soil.
Preparing Your Site and Planting Fruit Trees
When it comes time to plant a fruit tree, patience pays for itself many times over. Most of the problems we see with tree fruits come from two sources: failing to select appropriate crops for a site and failing to prepare the site before planting. We dealt with crop selection in Growing Tree Fruits in Short-Season Gardens. Now let’s consider site preparation.
Poor soil drainage is a very common cause of problems in a home orchard. Fruit trees on wet soils often fail to thrive, growing slowly, and eventually succumbing to root diseases. Peaches and other stone fruits are especially prone to problems on poorly drained sites.
Gardeners often add compost or other organic matter to heavy soils to improve drainage. In reality, most organic materials have high water-holding capacities and increase drainage problems when added to already heavy soils. Likewise, adding sand to soils on a low-lying site does nothing to improve drainage unless there is a way for water to drain away from the site.
Drainage tiles (buried pipes with holes along the sides) can be used to drain excess water away from a planting site, provided you have a lower-lying area for the water to drain to. For one or a few trees, raised planting beds twelve inches or more high can significantly improve drainage, particularly when heavy native soils are amended with sand or a lighter-textured soil is brought in to create the beds. For a fruit tree, a bed ten feet in diameter should suffice. The beds can be contained within walls or sloped from the centers outward. Apples and pears on dwarfing rootstocks and peach genetic dwarfs have been successfully grown in large (approximately 20 to 50 gallon) containers. Container culture requires great care to ensure adequate irrigation and fertilization, and to prevent girdling roots.
Gardeners like to improve their soils, and often do so by adding composts, manures, straw, sawdust, or other organic materials. There are both benefits and risks associated with soil amendments. Perhaps the greatest advantages to organic soil amendments are that they can increase water and nutrient holding capacities on light-textured soils and can be sources of plant nutrients.
Amendments also carry risks. Weeds, pests, and diseases can easily be brought into your garden through contaminated organic materials. Woody materials, such as straw, bark, and sawdust, can create severe nitrogen deficiencies in the soil as they decompose. Woody materials are broken down by microorganisms in the soil. These microorganisms take nitrogen from the soil to use for proteins and other compounds in their bodies. Until the woody material is decomposed and the microorganisms die, the nitrogen is unavailable to plants. An excellent strategy to avoid importing weeds, pests, and diseases and to avoid depleting your soil nitrogen is to thoroughly compost organic amendments before adding them to your garden.
When planting a fruit tree, dig a hole large enough to hold all of the roots without cutting any of them off and without bending the roots to fit into the hole. A good strategy is to dig the hole, then build a pyramid-shaped mound in the center of the hole and drape the roots over the mound. Be very careful to ensure that, after the soil has settled, the tree is at the same depth it grew in the nursery. Planting trees too deeply often results in collar and root rot and tree death. Also avoid planting too shallowly, which creates an unstable tree and exposes the collar and roots to excessive drying.
Most fruit trees are sold bare root or may come in pots up to about five gallons in size. Plant bare root trees as described above. Container-grown trees are planted similarly, but take particular care to inspect the root ball after the pot is removed and before planting. Use sharp pruning shears to cut through roots that circle around the root ball or cluster on the bottom of the ball. These could result in eventual girdling of the trunk. Be careful not to drop the tree, twist the trunk or root ball, or break open the root ball. Doing so can break off small feeder roots. Always lift trees from the bottoms of the root balls. Never lift a tree and pot or tree and root ball by the trunk.
A simple rule is that the only soil that goes back into a planting hole is the soil that came out of it. Never replace the soil with compost, peat moss, or potting soil. Never create a blend of soil and compost to fill a planting hole. Doing so creates a barrier at the sides and bottom of the hole that makes it very difficult for water or roots to penetrate to the soil outside the planting hole. Essentially, you create a pot without a hole in the bottom. If you want to amend the soil, before digging, apply up to six inches of amendment and till it into the soil across a five- to ten-foot diameter area centered where the planting hole will be.
Most fruit trees should not require staking when they are planted. As long as a tree remains upright, staking is usually not recommended for free-standing trees. Trunk strength develops as a tree sways in the wind and staking can actually create weak trunks that will not support crop loads. For special production systems, young apple trees can be trained to vertical poles for several years. The slender spindle production system is one example. Apples on dwarfing rootstocks are also sometimes grown on supporting trellis wires. For more information on training systems, refer to Training and Pruning Your Home Orchard.
Ensure that the soil around the tree does not become dry, but avoid overwatering. Your goal should be to keep the soil moist, but not waterlogged. Some gardeners like to build a shallow saucer around newly-planted trees by creating a raised lip of soil about 12 to 24 inches in diameter. This practice can be helpful on soils that drain well until the tree becomes established. On heavier-textured soils, building such saucers can cause problems with the trees. As a general rule, if you build a tree saucer and fill it with water, the water should have drained completely away within an hour or so. If not, remove the saucer. Check newly-planted trees twice weekly to ensure proper irrigation.
Assuming you have normally fertile soils, fruit trees are not usually fertilized at the time of planting or during the first growing season. A soil test is your best resource in determining this and helping you to spot trends in fertility over time. Some Idaho soils, however, are deficient in available phosphorus. You can safely add a cupful of steamed bone meal or 0-45-0 fertilizer to the bottom of a planting hole, mix it with a handful of soil, and plant your tree in the hole. Never add fertilizers containing nitrogen, potassium, or boron to planting holes.
Care of Fruit Trees
Healthy and productive fruit trees require regular care throughout the year. A few of the more important tasks are listed here. Click here for links to more complete guidance on fruit tree care.
In early spring before the new leaves appear, examine the trees carefully for signs of damage from winter cold, snow and ice, diseases, girdling or other damage from animals, and signs of pests or pest damage.
Prune your fruit trees. Normally, we prune fruit trees in late winter or early spring before the buds begin swelling. First remove any diseased or damaged wood. Damaged and diseased wood can be pruned out any time of the year. If the branch is or may be diseased, rinse your pruning shears after every cut in a solution of 20% household bleach in water or 70% ethyl or isopropyl alcohol. Do not compost diseased or pest infected branches.
Remove all sprouts arising from the roots and trunk below the graft union. Next, concentrate on building a strong structure that will support the branches and crop. Remove enough wood to maintain an open canopy that allows light to penetrate to the trunk and air to circulate freely through the tree. Most water sprouts come off at this time. Water sprouts are vigorous, vertical shoots that can easily develop into multiple leaders and create a crowded, hard to manage tree. With some crops, pruning can help manage the tree height by removing branches above a desired height. Height management through pruning works well for peaches, nectarines, and apricots. For apples and pears on dwarfing rootstocks, pruning is also valuable for controlling height. Controlling cherry and plum tree height with pruning can be difficult.
Fruit trees need regular fertilization to remain healthy and productive. How much fertilizer to add depends on the nutrients already available in the soil and the size of the trees. Home gardeners tend to over fertilize their trees, which delays or reduces blossom formation, produces poor yields and fruit quality, and results in vigorous growth of branches and leaves and increased pruning.
Large trees, such as apples on seedling rootstocks, require more nutrients than dwarf trees. Commercial fruit growers have laboratories analyze the leaves in mid summer to determine the nutrient status of the tree. For home gardens, start with the amounts in Table 1 below and watch your trees carefully. If a tree that is old enough to bear a crop produces lush shoots and dark green leaves but few blossoms, you are applying too much nitrogen and/or pruning off too much wood. If growth is slow, stunted, or yellowish, add more nitrogen. Apply fertilizers from early spring through the end of June.
|Nitrogen Source||Nitrogen Content (%)||Planting Year||Young Trees (rate per year since planting)||Mature Trees (six years or more from planting) (lb)|
|21-0-0 (ammonium sulfate)||21||0||3 oz||1|
|Dry manure (other then poultry)||1-2||0||3 lbs||15|
|Dry poultry manure||3-5||0||1 lb||5|
Some trees will produce more fruits than desirable. With too many fruits on a tree, the fruits tend to be undersized and may be scarred or misshapen by overcrowding. Overbearing can also interfere with the formation of next years flower buds on apples, pears, and other spur-forming fruit trees, and can cause the trees to bear heavily one year and produce few fruits the next.
For apples, pears, peaches, and nectarines, you can remove or thin some of the developing fruits to produce larger, more attractive fruits at harvest. Apples and pears naturally thin themselves, somewhat, in a process called “June drop”. Suddenly hundreds of apparently healthy little fruits drop from the trees. This is a normal process and no cause for alarm. Commercial growers apply chemical sprays to thin their orchards, but hand thinning is best for home gardens. Begin by removing small, weak fruits. Then thin remaining fruits that are tightly clustered to leave one to three inches between fruits. Timing is important. Thin apples within 40 days of full bloom (when 50% or more of the flowers are open). Thin pears within 60 days of full bloom. Thin peaches about 70 days past full bloom.
The most important tool in managing pests and diseases in your orchard is regular scouting. At least weekly, closely examine the trunks and branches, flowers, leaves, and fruit for signs of pests or diseases. If you are not sure what a problem is or how to control it, get help from your county extension office, nursery or garden center.
Just as the buds are swelling, but before they open in early spring, you may wish to apply a spray of dormant crop oil. Even better is a mix of dormant oil and sulfur. The oil helps control pests by smothering the overwintering pests and eggs. Beneficial insects and mites that feed on these pests usually overwinter elsewhere and are not harmed by the oil. Various sulfur formulations are available to gardeners for dormant applications are very valuable in helping manage fungal diseases. Your garden center can advise you on suitable products. Always follow label directions and regulations carefully. Some dormant oils and sulfur treatments are approved for organic fruit production.
When we consider pruning, we naturally think of early spring. This is appropriate for the most part, because removal of branches on a plant is best done after winter cold has abated and before the plants leaf out. This helps prevents excessive weeping (sap flow from the wound) and allows time for wounds to heal during the summer months. However, there are practical reasons for completing some minor pruning during the summer.
Pruning may be needed to remove damaged or diseased branches that were not apparent during the spring. There may also be a need to remove branches with winter injury, something that does not become visible until warm weather arrives. For some shrubs, pruning may also be needed to remove spent flowers to encourage the growth of new blossoms. Fruit trees can be pruned to remove some fruit in years that fruit set is excessively high. This will result in larger fruit and help prevent alternate bearing, the tendency for fruit trees to grow fruit only in every other year.
One of the main reasons to prune shrubs and trees in the summer is to control size. When pruning is done only in the spring, trees and shrubs tend to sucker where old branches are removed. These new branches grow rapidly and if left in place result in overall increased size. Removal of these new branches during the summer helps a tree or shrub to remain small in stature and more compact in shape. It will also decrease the amount of pruning needed during the next spring.
Even conifer trees can by pruned to control size. This is done by clipping off most of the “candle”, the new sprout of soft growth that emerges in the spring. This will help keep a potentially large tree small, while at the same time helping to thicken the new growth. When pruning evergreens, it is important not to remove all of the new growth (except occasionally). This will leave only older wood that will eventually lose its needles and become unattractive.
Pruning for size control with shrubs may take the form of shearing, something we do to manage the size and shape of hedges and specimen plants in the yard. Shearing not only removes lanky, tall growth, but causes the plant to branch out and become thicker.
So, don’t be afraid to break out the pruning tools in July. Selective summer pruning will improve the look of your yard.
How Do I Transplant Existing Trees?
Do you have a shrub or tree that is planted in the wrong place in your yard? Does your neighbor have a tree that they will let you have, if you move it yourself? Have you wondered how to move a tree and keep it alive? If a tree or shrub is not too big, you can transplant it yourself and save the cost of having it done professionally. Be prepared for some hard work, and take the time to learn how to do it properly. If you work carefully, you can expect a high probability of success in keeping the tree alive and growing after transplanting is complete. The following information will guide you in the transplanting procedure. Recognize that this process can be used for all woody plants, trees, shrubs, or vines. Due to size, trees are the hardest to move, so they will be used as the example
When Should I Transplant?
Transplant early in the spring, after soil frost is gone but before new growth occurs. Once the buds start to break and grow, transplant survival decreases drastically. Plants dug during, or soon after bud break, are intolerant of transplanting especially evergreen trees, but all trees will do better if moved when they are dormant.
What Basic Transplanting Method Should I Use?
Plan to use a ball-and-burlap method for moving a tree. This technique involves moving a large ball of undisturbed soil along with the roots. Keeping soil around the roots is important for survival of trees that have grown unrestricted or unpruned in a yard or landscape situation. The method for digging a root ball will be described in detail below.
How do I Decide if a Tree is Moveable?
The most important consideration for assessing ability to transplant a tree is size. Small trees survive transplanting better than large trees, so the smaller the better. Also, the bigger the tree, the larger the soil ball that should be maintained around roots. A bigger root ball means more weight that must be moved. You must match necessary weight with personal physical ability and tools available for transplanting.
A 24-inch diameter root ball dug to 16 inches deep will weigh anywhere from 200 to 300 pounds, so tree size quickly restricts what is physically possible.
Due simply to the weight involved, it is probably wise to avoid moving trees whose trunks are larger than 2.5 inches in diameter. Alternately, they should simply be cut down or moved with the help of a professional using a mechanical tree spade.
How do I Determine Proper Root Ball Size?
First, figure out the proper diameter for the root ball. As a general rule, for every ONE inch of trunk diameter (measured at 4 inches above the ground), the soil root ball should be 12 inches in diameter. So, if you have a tree whose trunk is 2 inches in diameter at 4 inches above the ground, the root ball should be dug so that it is 24 inches in diameter (with the trunk in the center). Keep in mind that tree height is NOT a factor here. The root ball diameter should be based on the trunk diameter.
Diameter less than 20 in. Depth not less than 75% of diameter or 3/4 of width.
Diameter 20 to 30 in. Depth not less than 66-2/3% or 2/3 of width.
Diameter 31 to 48 in. Depth not less than 60% or 3/5 of width. Balls with a diameter of 30 in. or more should be drum laced.
Next, you will need to decide how deep to dig the root ball for the trees by using the following information:
- If the root ball diameter < 20 inches: root ball depth should be 75% of the diameter.
- If the root ball diameter is > 20 inches but < 30 inches: root ball depth should be 66% of the diameter.
Detailed Instructions for Transplanting a Tree
- Gather tools to complete the transplanting job. A sharp shovel or spade is required. Burlap is used to hold the soil ball together, and nails can be used to “pin” the burlap in place to hold the material on the root ball. Twine can be used to provide extra support to hold the soil ball together. Hand pruners and a sharp pocket knife can be used to prune or cut branches or roots as needed.
- Check the trunk diameter 4 inches above the ground. Determine the proper root ball diameter and depth using the rules given above. Once you know the diameter then roughly mark a circle of the proper diameter on the ground around the tree with the trunk in the center.
- Dig at least one or two inches further out than the mark for the root ball. Use the BACK of the shovel toward the trunk, and push the shovel straight into the ground. Once the shovel sinks into the soil as far as you can comfortably push it, then lift it STRAIGHT OUT of the ground. DO NOT push on the shovel toward the root ball since you can break up the root ball. The idea is to keep the root ball intact without cracking it.
- Once you have dug all the way around the trunk by pushing a SHARP shovel into the soil, then you can use the shovel OUTSIDE of your vertical cuts to remove soil. In this way, you are starting to make a vertical cylinder of soil – the root ball – around the trunk. As you remove the soil, avoid putting pressure on the vertical cylinder of soil (here after called the root ball) so that you avoid cracking it. You want the root ball intact.
- After removing the excess soil outside of your cut lines, put the BACK of the shovel against the root ball again and dig deeper this time, digging all the way around the root ball and keeping the shovel straight vertically as you dig. Again, avoid putting pressure on the root ball so that you avoid cracking it. After digging deeper all the way around the root ball, remove the soil outside of your cuts so that you have room to dig deeper again.
- To make your digging easier, you should probably clear about 8 inches (or more) of soil away from your vertical cuts so that you have room to dig deeper. The more soil you remove to the outside of your cuts, the easier you can dig down, BUT moving that soil out requires plenty of space and your energy to dig it and move it out.
- As you make vertical cuts for the sides of the root ball and dig deeper, you can begin to taper the root ball, perhaps angling your cuts 1 to 2 inches toward the center of the ball for every 12 inches deep that you dig. In this way, you will have a root ball that is wider at the top and tapered to its base. Since you also should have started the root ball a few inches wider than was necessary, you can make vertical cuts to make your root ball smaller while tapering its shape toward the bottom of the ball. As you make the vertical cuts on the soil cylinder/root ball, you may encounter some very thick roots. If your shovel is sharp enough, it should cut the root(s) with a few good hard strokes or pushes. If the root is either too large or your shovel too dull, AVOID continually hitting or slamming the root with the shovel, since this practice causes excess root damage and will probably help break the root ball. Instead, have a sharp pair of loppers (or other sharp pruning tool) with you to cut the root so that you can continue digging after the root is cut.
- Once you dig deep enough, based on the depths provided above, you should start to undercut the root ball. This procedure involves using your shovel to make/cut the bottom of the root ball. You will need to cut under the cylinder of soil from the outside, so this procedure is more readily accomplished (but not necessarily easily accomplished) if you removed the soil from a large area outside of the root ball. Undercutting the root ball must be done carefully since you can easily crack the root ball and ruin all your efforts to this point. The goal of undercutting is to cut roots that may be growing vertically (such as the taproot) or close to vertical. To undercut, use the shovel in the regular way (shovel face now toward the tree) and push the blade toward the center of the root ball going around the ball several times. Digging the root ball (soil cylinder) a little deeper than needed (according to the nursery stock standards) will enable you to remove soil – after making some horizontal cuts – at the bottom and ensure that vertical roots are cut. Trying to move the soil ball with a few roots intact under the root ball (particularly the taproot) will nearly always break open the ball.
- Once you have dug under the root ball and cut all the roots, you will need to protect the root system so that the soil holds together and the ball does not crack when trying to move the soil. Typically, burlap is used for holding the root ball together, but other types of material can be used as long as the material is strong enough not stretch and break when trying to tie it around the soil ball. You will need different sized squares of material to hold the soil together depending on the ball size. For example, a 24-inch diameter root ball may require a 36-inch by 36-inch square piece of burlap.
- Once the root ball is cut free in the bottom of the hole, take the burlap square and fold a corner of it down so that it goes to the bottom of the hole. Fold about one-quarter to one third of the burlap down. Next, the long diagonal (from corner to corner) of the burlap is tied around the root ball, using the burlap as a band to hold the soil in place. If you are unable to tie the material around the root ball, use a larger piece of material. After tying the burlap tightly around the root ball, shift the root ball (carefully) so that you can grab the folded down corner of material and pull it under the root ball. In this way, you will have the material under the root ball and can cover the bottom and sides of the ball. Once you grab the corner of the material and cover the bottom of the ball, you may need to re-tie the material around the root ball. As you complete these procedures, be careful to avoid breaking the root ball.
- Once the burlap or supporting material is all around the root ball, you can pull the root ball out of the hole by lifting on the soil root ball NOT the tree trunk. Once the root ball is out of the hole you can shift or re-tie the burlap or supporting material as needed. Usually nursery professionals use pinning nails to make the burlap tight on the ball. Also, for root balls larger than 30 inches in diameter, supporting material, such as twine, wire baskets, or even chicken fencing are recommend for supporting the soil ball since it can break easily.
What do I do next?
- The shrub or tree should be replanted to its new location as soon as possible, hopefully within one week. In the mean time, prevent the root ball from drying out and try to keep the roots cool. If the root ball must remain out of the soil for more than a week, consider burying the ball in an organic mulch to retain moisture and reduce the soil temperature.
- Finally, plant the tree in its new location. Dig the new planting hole for your tree or shrub to the same depth as the root ball. Do not bury it too deep. See the planting instructions under the Trees, Shrubs, and Vines section of this web site for more details.