LA Course #GCE-1-1401
Bare Root Tree Planting Basics and Two Alternate Methods
Edited by Len Phillips and Richard W Gibney RLA/ISA, updated January 2021
Sections Go directly to the section by clicking on the title below
Bare Root Tree Planting Basics and Two Alternate Methods
Edited by Len Phillips and Richard W Gibney RLA/ISA, updated January 2021
Sections Go directly to the section by clicking on the title below
Note: Click on green text in each section for more information and photos.
Bare root trees are about as basic as trees come. They are affordable, simple to handle, and adapt to transplanting more quickly than trees bought in containers or balled and burlapped. The following article discusses the advantages and disadvantages of bare root planting along with tips for how to insure success in a bare root planting operation. It is followed by two alternative practices gaining popularity: bare root planting with a pneumatic device (Air-Spade®) and washing roots before planting. New tools and knowledge of root growth have made it possible to move away from traditional methods and toward more efficient and cost effective ways to plant trees.
Bare Root Tree Planting – the basics
What are the advantages of planting bare root trees?
What are the disadvantages of planting bare root trees?
• Less time to plant: Once they leave the nursery, bare root trees need to get in the ground or be in long- term storage within a week at the longest. With no soil or water, the roots can dry out and die if left exposed for any time more than an hour.
• Short planting window: Bare root trees need good soil moisture, so mid spring (before bud break) and mid fall (after leaf drop) are the best two installation times.
• Restricted availability: Some species may not be available bare root, and some nurseries may not have trees available for bare root retail sale at all.
• Potential to blow over: Without the mass of soil around the roots, there is a perception that the tree could easily blow over in high winds. However with the use of new tree stabilizing devices that hold the roots to the bottom of the planting hole, it is highly unlikely this will happen.
What are the best techniques to follow for bare root tree planting?
Why hasn’t everyone switched to bare root planting?
First, not all species will tolerate bare root planting. This is especially true of trees that have a tap root. Secondly, with any tree planting there is an inevitable holding period between digging the trees and planting them. During this period, root desiccation is the most critical disadvantage to planting bare root trees. In the past, people put wet straw around the roots or coated them with a mud slurry. These methods did not prove satisfactory or practical; the straw did not protect fine roots adequately and the mud slurry tended to dry out and chip off or break the root. Now however, a synthetic, non-toxic water-absorbing compound called hydrogel solves the desiccation problem for that critical time between digging and replanting. Planting the trees temporarily in Missouri gravel beds or wood chips and providing irrigation have proven to be successful in keeping the trees alive and healthy between the time of digging to the time of installation.
Planting Tips for Maximum Survival
What are the advantages of planting bare root trees?
- More root mass: Bare root trees can have up to 200% more roots than B&B or container trees, depending on the soil and transplanting history at the nursery. The reason for this is the harvesting machinery for bare root trees digs a much larger root system than the tree spade used for B&B digging. Plus, with bare root trees you won’t rob nurseries of their valuable field soil.
- Lower cost: You can plant more trees, less expensively. Without extra labor and materials, bare root trees cost the seller and the buyer less. Bare root trees are one-half the cost of B&B trees. Because they are so much lighter and many more can fit on the bed of a truck, they are cheaper to ship.
- Easier planting: A young tree without soil weighs little, so it is easy to move and plant. Planting a bare root tree costs virtually nothing when done by volunteers with shovels.
What are the disadvantages of planting bare root trees?
• Less time to plant: Once they leave the nursery, bare root trees need to get in the ground or be in long- term storage within a week at the longest. With no soil or water, the roots can dry out and die if left exposed for any time more than an hour.
• Short planting window: Bare root trees need good soil moisture, so mid spring (before bud break) and mid fall (after leaf drop) are the best two installation times.
• Restricted availability: Some species may not be available bare root, and some nurseries may not have trees available for bare root retail sale at all.
• Potential to blow over: Without the mass of soil around the roots, there is a perception that the tree could easily blow over in high winds. However with the use of new tree stabilizing devices that hold the roots to the bottom of the planting hole, it is highly unlikely this will happen.
What are the best techniques to follow for bare root tree planting?
- Use any technique you can to reduce the time the tree roots are bare.
- Order 1 1/2" - 2" (3 - 5 cm) trees to be dug within 24 hrs of pickup at the nursery, otherwise be sure they are stored in a cool, moist place where the roots can be protected from sun and wind
Why hasn’t everyone switched to bare root planting?
First, not all species will tolerate bare root planting. This is especially true of trees that have a tap root. Secondly, with any tree planting there is an inevitable holding period between digging the trees and planting them. During this period, root desiccation is the most critical disadvantage to planting bare root trees. In the past, people put wet straw around the roots or coated them with a mud slurry. These methods did not prove satisfactory or practical; the straw did not protect fine roots adequately and the mud slurry tended to dry out and chip off or break the root. Now however, a synthetic, non-toxic water-absorbing compound called hydrogel solves the desiccation problem for that critical time between digging and replanting. Planting the trees temporarily in Missouri gravel beds or wood chips and providing irrigation have proven to be successful in keeping the trees alive and healthy between the time of digging to the time of installation.
Planting Tips for Maximum Survival
- Bare root trees should be dug during the dormant season.
- The tree roots should be dipped in a slurry of a hydrogel then stored in large, pleated plastic bags until planting.
- Before leaving the nursery, branches should be wrapped with twine to prevent breakage in transit.
- Trees and roots should be kept covered, shaded, and moist until planting in the ground.
- Any broken roots should be snipped and the tree put in a bucket of water for 12 – 24 hours before planting.
- A growth stimulant should be added to the bucket of water (Superthrive, Rootone, organic preparations, etc.) to kick-start root growth.
- Each tree should be labeled with its intended site location before it gets dipped and bagged so that when the planting laborers install the trees, they can quickly go to the location on the label and minimize dessication. You may also want the tree to be labeled with the tree’s scientific name, its common name, and the date of planting.
- The planting hole should be no deeper than the root system, but at least three times as wide. The best hole digger is a backhoe that makes a simple shallow, saucer-shaped hole. The bottom of the hole should be scraped so the soil will be loose for new roots to grow into.
- Depending on the tree's root system, a cone of soil can be made to rest the tree on to get the tree to the right height so that the trunk flare (where the roots meet the trunk) is at one inch above the finished grade level. The trunk flare of bare root trees is obvious and the proper planting depth is easy to determine. However, do not mistake the point of graft on cultivars for the trunk flare. The graft must be above ground.
- Roots should be spread out evenly over the planting area.
- The planting hole should be filled with the soil just removed over the tree roots.
- The soil around the roots should only be lightly amended if it is heavily compacted and/or low in nutrient value. Roots have a tendency not to venture out from the fluffy amended soil and the tree can become root-bound. Filling a hole with amended soil can also create drainage problems. Water tends to stay in the amended area and when the roots get waterlogged, the tree will die.
- When half of the backfill has been replaced, water should be added to the hole to help collapse air pockets. If the soil does not wash in and around the roots, the soil should be firmed with the wood end of a shovel to gently poke out air pockets. A foot should not be used since heavy compaction around the roots is not good for the tree.
- The hole should be backfilled with the remaining soil and gently firmed by hand. The soil should not be mounded against the trunk and the beginnings of the trunk flare should show above the ground level.
- A saucer should be made approximately 3 feet (1 m) in diameter around the tree and filled with water. The water should seep in slowly and reach the depth of the roots. The tree needs to stay hydrated for the first 24 hours.
- The saucer should be covered with wood chips or shredded bark mulch to retain moisture and control weeds, but the mulch should not be placed right next to the trunk.
- Three to four inches (8 – 10 cm) thick is a good depth for mulch over tree roots.
- Consider suggesting the use of tree irrigator bags. They hold 20 gallons (75 l) of water and slowly release it to the roots, saving watering time and aiding in tree establishment.
- Fertilizers are not recommended for newly planted trees.
- Staking is not necessary and can even be detrimental for most young trees. The exceptions are an
extremely windy site, a tree with an unusually small root system, an unusually large canopy relative to a tree’s root system, a tree whose trunk is seriously bowed or in high traffic areas where vandalism is feared.
Bare Root Planting With Pneumatic Soil-excavating Tools
Bare root (BR) transplanting with a pneumatic soil-excavating tool is actually an old method using modern tools and technology developed in the late 1990's. A pneumatic tool known as the Air-Spade® was introduced to the tree industry and promoted mainly to diagnose and treat root problems. The Air-Spade® is a patented venturi nozzled apparatus that attaches to an air compressor modified to generate a supersonic velocity of air to dislodge soil. When used around trees, it can:
When the pneumatic soil-excavating tool is being used for transplanting trees BR, the soil is excavated from above and below the roots. This process allows the tree to retain up to 95% of the root mass, which results in little or no transplant shock. This technique provides the ability to transplant trees throughout the growing season (spring, summer, and fall) with success. After using the pneumatic tool, the bare roots are sprayed with water and covered with wet burlap for transporting. Regardless of the weather, season, and species, most trees do not even show signs of wilt during the pneumatic tooling use and the moving process. Trees up to 15 inches (38 cm) DBH are easily moved with this bare root technique.
Labor costs for using the soil-excavating tool is more than using a tree spade, but equipment costs are much less. Therefore, the total cost for using the pneumatic tool is half the cost of the tree spade. Plus the tree survival rate is much higher with a pneumatic tool than with the tree spade.
Steps Taken for Moving Trees with a Pneumatic Soil-excavating Tool
People who have used this technique are confident that bare root transplanting is perhaps the best way to relocate a tree and the pneumatic soil-excavating tool will revolutionize transplanting in our industry.
Bare root (BR) transplanting with a pneumatic soil-excavating tool is actually an old method using modern tools and technology developed in the late 1990's. A pneumatic tool known as the Air-Spade® was introduced to the tree industry and promoted mainly to diagnose and treat root problems. The Air-Spade® is a patented venturi nozzled apparatus that attaches to an air compressor modified to generate a supersonic velocity of air to dislodge soil. When used around trees, it can:
- reduce soil compaction,
- till the soil,
- reveal girdling roots,
- locate the trunk flare,
- locate roots for utility line installation,
- investigate root damage,
- check the adequacy of the root structure,
- accurately diagnose root diseases.
When the pneumatic soil-excavating tool is being used for transplanting trees BR, the soil is excavated from above and below the roots. This process allows the tree to retain up to 95% of the root mass, which results in little or no transplant shock. This technique provides the ability to transplant trees throughout the growing season (spring, summer, and fall) with success. After using the pneumatic tool, the bare roots are sprayed with water and covered with wet burlap for transporting. Regardless of the weather, season, and species, most trees do not even show signs of wilt during the pneumatic tooling use and the moving process. Trees up to 15 inches (38 cm) DBH are easily moved with this bare root technique.
Labor costs for using the soil-excavating tool is more than using a tree spade, but equipment costs are much less. Therefore, the total cost for using the pneumatic tool is half the cost of the tree spade. Plus the tree survival rate is much higher with a pneumatic tool than with the tree spade.
Steps Taken for Moving Trees with a Pneumatic Soil-excavating Tool
- The tree's roots should be hydrated thoroughly before excavating it by watering deeply at least 72 hours before the move. Clay soil blows out best when it is damp. Sandy soil blows out best when it has drained a bit.
- The excavation process should be started by making a circular trench at the drip line using a small backhoe. With that completed, the backhoe should be used to carefully excavate inward toward the trunk until roots are discovered. Next, the pneumatic soil-excavating tool should be used to blow soil outward and into the circular trench.
- The exposed roots should be kept as moist as possible during the digging and lifting of the roots. As a section is completed, the roots should be gathered and tied up in a pigtail fashion, then the pigtail should be raised and tied to the tree trunk or lower branches as the roots are moistened again. The pnematic tool does cause some root drying so moistening the roots is very important.
- This process should be continued moving around the tree.
- Once all of the roots are exposed and tied up to the tree, the tree is ready to be moved to the new location, which should have been dug the same size as the hole from which the tree is being removed from.
- The tree should be planted at the same grade as it was in its original location, leaving the trunk flair exposed.
- The roots should be untied from the trunk of the tree and spread out in approximately their same orientation from which they came. The roots should be moistened again.
- If the soil is heavily compacted and/or low in nutrient value, options at this point include adding some soil amendments like compost, and/or hydrogel to maintain moisture levels during the re-establishment period.
- The soil excavated from the new location should be backfilled into the planting hole. The best way to backfill is with labor and shovels. However, if equipment is used be sure it is equipped with wide tracks or tires. Soil compaction is not acceptable after all this effort to protect and save the tree.
- A berm of soil should be built at the edge of the new planting excavation.
- Immediately after backfilling, the saucer area should be flooded with water to eliminate air pockets.
- The tree should be irrigated throughout the growing season to ensure the tree becomes established.
- Staking is not necessary and may only be useful on a windy site.
- As little as 5%-15% of roots are cut, unlike the conventional methods which cut between 50%-85% of the root mass. Most of the trees roots are moved with the tree, compared to 30% with a tree spade or 5% by B&B. This means a minimized transplant shock. The tree is also significantly lighter in weight for transporting.
- The pneumatic soil-excavating tool is considered a less expensive option to transplanting than with a tree spade.
- Smaller machines are needed to lift the tree.
- The pneumatic tool is useful for transplanting specimen trees.
People who have used this technique are confident that bare root transplanting is perhaps the best way to relocate a tree and the pneumatic soil-excavating tool will revolutionize transplanting in our industry.
Washing Roots Before Planting
Many problems related to newly installed trees can be traced to root defects, poor root preparation, and poor installation practices. These factors result in circling and girdling roots, root decline, infestations by secondary pests and diseases, and early tree failure. Trunk flare depth is also a problem that is not discovered until the tree has been dug and planted in a new location that often results in an early death of the tree.
Field applications over the past two decades have demonstrated that root washing balled and burlapped (B&B) and containerized trees leads to substantial increases in tree establishment and survival. The process basically changes container and B&B stock to bare root stock. The washing will expose the entire root system and reveal the trunk flare and graft union. It allows for remediation of damaged roots and it eliminates any disparity of texture between the soils of the root ball and the planting site.
The Process
In order to achieve success with the root washing process, there are 9 recommended steps to follow.
2. The tree should be placed in a large container where the soil can easily be washed off or removed by hand or small hand tools. Soil that is packed around the root should be washed off with a hose or by raising the
tree up and down in the water in the container. Soaking also allows the soil to slough off gently. The
duration of soaking depends on the amount of clay in the root ball and the soil compaction level.
3. Look for root defects and if any, they need to be removed.
4. The planting hole should be dug to be only as deep as the root system and at least three times as
wide. The hole dimensions will vary depending on the size of the root system, after the soil has been
removed. The hole should resemble a shallow saucer.
5. A soil mound should be formed in the center of the hole to support the root crown of the tree and its roots
arranged radially.
6. The hole should be backfilled with the soil just removed while adding water. Do not use soil amendments
unless the soil test shows deficiencies.
7. The water used for planting should preferably be from the container used to wash the soil off the roots.
This water will contain the nutrients and microbes that assisted the tree's growth at the nursery. Water will
settle the soil and the tree roots will hold the tree upright. If soil tests indicate a nutrient deficiency, the
appropriate fertilizer should be added at this time. Added fertilizer should not be used on the bare roots,
because the fertilizer will burn them. The roots or the root zone should not be stepped on, not even to pack
the roots down. This causes compaction to the soil. Instead, a gentle jiggle of the tree back and forth as
the water is draining is recommended. This will encourage the soil to come into contact with the roots.
8. Once the soil is added to be level with the trunk flare, a mechanical root stablizer system can be added if
the tree has potential to tip and then mulch the entire planting circle. The depth will vary with the mulch
texture. Fine particle mulch should be 2 inches (5 cm) thick or less, while coarse mulch should be 4 inches
(10 cm) thick or less. The mulch should start at least 3 inches (7.5 cm) from the trunk of the tree and
extend outward to the edge of the planting hole.
9. The tree should be watered for the next three years adjusting the amount of the water according to
the annual growth and natural rainfall. The amount of water will vary according to the soil type and
rainfall.
Investing the extra time to prepare and install trees properly will pay future dividends of reduced maintenance and a longer life for the tree. Furthermore, washing the roots saves labor during installation because the holes are shallower and less heavy equipment is required.
Sources: Bare Root Planting – the basics
The test that follows contains 30 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
LA CES will award 1.0 PDH (HSW) credit for a passing grade. North Carolina Board of LA and New Jersey Board of Architects have approved this course for 1.0 credits.
The cost for taking this test is $20 per credit. If you purchase an annual subscription for 12 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report your passing test score to LA CES. If you are also ISA* certified we will report your passing score to ISA for no additional cost. Please be sure to add your ISA Certification number when you sign in. Tests with passing scores may be submitted only once to each organization.
*ISA has approved this course for .5 CEUs per section for a total of 1.5 CEUs applied toward Certified Arborist credit or 1.0 CEU may be applied toward BCMA Practice credit and .5 Science credit.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. If you are an ISA and/or CLARB member, please be sure to include your certification/member number(s) along with your LA license and ASLA numbers.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks after that.
LA CES maintains a record of earned PDH credits on their website http://laces.asla.org/
ISA maintains a record of earned CEU credits on their website http://www.isa-arbor.com/
Many problems related to newly installed trees can be traced to root defects, poor root preparation, and poor installation practices. These factors result in circling and girdling roots, root decline, infestations by secondary pests and diseases, and early tree failure. Trunk flare depth is also a problem that is not discovered until the tree has been dug and planted in a new location that often results in an early death of the tree.
Field applications over the past two decades have demonstrated that root washing balled and burlapped (B&B) and containerized trees leads to substantial increases in tree establishment and survival. The process basically changes container and B&B stock to bare root stock. The washing will expose the entire root system and reveal the trunk flare and graft union. It allows for remediation of damaged roots and it eliminates any disparity of texture between the soils of the root ball and the planting site.
The Process
In order to achieve success with the root washing process, there are 9 recommended steps to follow.
- The entire wire basket, twine, and burlap or the container from the root ball should be removed. This work should be done in a location where the soil can remain or where it can easily be transported to another site.
2. The tree should be placed in a large container where the soil can easily be washed off or removed by hand or small hand tools. Soil that is packed around the root should be washed off with a hose or by raising the
tree up and down in the water in the container. Soaking also allows the soil to slough off gently. The
duration of soaking depends on the amount of clay in the root ball and the soil compaction level.
3. Look for root defects and if any, they need to be removed.
4. The planting hole should be dug to be only as deep as the root system and at least three times as
wide. The hole dimensions will vary depending on the size of the root system, after the soil has been
removed. The hole should resemble a shallow saucer.
5. A soil mound should be formed in the center of the hole to support the root crown of the tree and its roots
arranged radially.
6. The hole should be backfilled with the soil just removed while adding water. Do not use soil amendments
unless the soil test shows deficiencies.
7. The water used for planting should preferably be from the container used to wash the soil off the roots.
This water will contain the nutrients and microbes that assisted the tree's growth at the nursery. Water will
settle the soil and the tree roots will hold the tree upright. If soil tests indicate a nutrient deficiency, the
appropriate fertilizer should be added at this time. Added fertilizer should not be used on the bare roots,
because the fertilizer will burn them. The roots or the root zone should not be stepped on, not even to pack
the roots down. This causes compaction to the soil. Instead, a gentle jiggle of the tree back and forth as
the water is draining is recommended. This will encourage the soil to come into contact with the roots.
8. Once the soil is added to be level with the trunk flare, a mechanical root stablizer system can be added if
the tree has potential to tip and then mulch the entire planting circle. The depth will vary with the mulch
texture. Fine particle mulch should be 2 inches (5 cm) thick or less, while coarse mulch should be 4 inches
(10 cm) thick or less. The mulch should start at least 3 inches (7.5 cm) from the trunk of the tree and
extend outward to the edge of the planting hole.
9. The tree should be watered for the next three years adjusting the amount of the water according to
the annual growth and natural rainfall. The amount of water will vary according to the soil type and
rainfall.
Investing the extra time to prepare and install trees properly will pay future dividends of reduced maintenance and a longer life for the tree. Furthermore, washing the roots saves labor during installation because the holes are shallower and less heavy equipment is required.
Sources: Bare Root Planting – the basics
- Bassuk, Nina, "Creating the Urban Forest: the Bare Root Method.", Ithaca, NY, 2000.
- Christman, Laura, "Bare Essentials: 6 Tips for Growing Bare Root Trees", The Redding Searchlight, Redding, CA, January 9, 2010.
- Foti, Matt, "Bare Root Planting with an Air-Spade®", New England Grows lecture. 2011.
- Howe, Deborah, "Another air-tool bare-root transplanting", Taking Place, July 29, 2009.
- Howe, Deborah, "Roots First", American Nurseryman, December 2008.
- Appleton, Bonnie and Jim Flott, "Back to Basics", Nursery Management
& Production, May 2009. - Community Forestry Consultants Inc., "Root Washing Method" lecture at New England Grows, Feb. 7, 2013.
- Flott, Jim, "Don't Plant Trees, Plant Roots", City Trees, The Journal of the Society of Municipal Arborists, 42 (2), March/April 2006.
The test that follows contains 30 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
LA CES will award 1.0 PDH (HSW) credit for a passing grade. North Carolina Board of LA and New Jersey Board of Architects have approved this course for 1.0 credits.
The cost for taking this test is $20 per credit. If you purchase an annual subscription for 12 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report your passing test score to LA CES. If you are also ISA* certified we will report your passing score to ISA for no additional cost. Please be sure to add your ISA Certification number when you sign in. Tests with passing scores may be submitted only once to each organization.
*ISA has approved this course for .5 CEUs per section for a total of 1.5 CEUs applied toward Certified Arborist credit or 1.0 CEU may be applied toward BCMA Practice credit and .5 Science credit.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. If you are an ISA and/or CLARB member, please be sure to include your certification/member number(s) along with your LA license and ASLA numbers.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks after that.
LA CES maintains a record of earned PDH credits on their website http://laces.asla.org/
ISA maintains a record of earned CEU credits on their website http://www.isa-arbor.com/