Planting and Transplanting Trees and Shrubs in the Home Landscape
By Thomas M. Rathier
The Connecticut Agricultural Experiment Station
153 Cook Hill Rd.
Windsor, CT 06095
Telephone: (860) 683-4977 Fax: (860) 683-4987
Few projects around the home are more rewarding than successfully establishing a landscape planting of trees and shrubs. Whether it's a plan designed by a landscape architect or the homeowner or simply a planting of a single plant, a successful planting is usually the result of careful planning. Consideration of the planting site, plant selection, planting methods and post-planting care are vital to success.
Site selection and plant considerations. Site and plant selection are closely related. It isn't always possible to select ideal sites in a given home landscape and care must be taken to match the plant material to the site. An important factor to consider is the past history of the site. If other plants have died or grown poorly on the site, it would be important to determine the cause before replanting there. If the site has never been planted before, then attention to the site needs will help prevent failures.
Consideration of the root zone is probably the most important. Without adequate aeration and moisture and proper fertility, root growth will be limited. Poorly drained soils or soils that have been compacted by heavy traffic can often be improved. Leaving these problems uncorrected reduces a plants chances for survival. If the roots of other surrounding trees and shrubs are growing in the planting area, competition for moisture and nutrients may be a problem. Close proximity to paved areas and structures may limit root growth as well. Evaluating soil pH and fertility in advance with a soil test can prevent serious problems. Most of these problems can be avoided by either altering the site, choosing the appropriate plant material or both.
Above ground considerations include light and moisture availability and exposure to adverse weather and traffic. Sites that are shaded by structures or other plants will not support plants that require full sun. Conversely, full sun locations may not be ideal for plants that have low light requirements. The availability of irrigation water is important, especially in the first year after planting. Areas that are not convenient to irrigate regularly are best left to plants that are able to withstand drought conditions. Sites exposed to climate extremes such as high or freezing temperatures usually require hardy plant material. Sites near areas of heavy traffic are best planted with material that can withstand trampling and abrasion.
Finally, some consideration of plant needs and growth habits is important. Plants requiring little care are more suited for remote areas whereas those with more needs can be planted in areas that can be cared for more intensively.
Selection of plants for the landscape can be a challenge. Plants that have been grown in field or container nurseries are usually more easily adapted to a wide variety of sites. Plants from nurseries have the advantage of well developed root systems that make plantings more successful. Field grown plants usually have a wrapping of burlap or plastic around the root ball or are occasionally available in a bare root condition. Container grown plants are usually grown in soilless media and the root balls fit the shape of the container.
Planting considerations. Plants are most successfully established in the home landscape when as little time as possible elapses between obtaining the plants and planting. When it's necessary to keep plants for a few days prior to planting, they will require regular waterings and are best kept in a shady location.
For most soils, the planting hole usually needs to be only as deep as the root ball of the plant. In sandy soils, somewhat deeper can be helpful. A hole width twice the diameter of the root ball is usually suitable. Contact between the shovel and the sides of the hole can result in a glaze that can prevent root growth out into the surrounding soil. Glazing can be avoided by scratching the sides of the hole before placing the plant. Although it's a popular practice, adding a layer of sand or organic matter to the bottom of the hole usually has no benefit and, in many cases can be detrimental.
Prior to planting, plastic wrappings or containers need to be removed from the root balls. Burlap wrappings can remain in the ground and will eventually degrade. It is helpful to arrange the roots of bare root plants in the hole in a way that minimizes circling roots that could eventually strangle the plant. Root balls of container grown plants need to be vertically cut in several spots around the ball to discourage circular root growth.
Because a certain amount of settling will occur, the root ball needs to be placed in the hole so that the original soil line is slightly higher than that of the surrounding soil. After settling, the soil lines will eventually match.
When setting the plant in the hole, consideration of its appearence is important. It's always worth the time to step back from the planting to see how the plant looks with regard to its surroundings before backfilling. It is also wise to consider setting the plant in a way that avoids future problems with branches extending into areas of activity such as sidewalks, driveways, play yards and powerlines.
Backfilling planting holes has been the subject of considerable research over the years. It has been traditionally assumed that amending the backfill soil with organic matter such as peat moss or compost improves the plant's chances for survival. It's important to remember, however, that the plantings that are most successful are those where the roots grow out into the surrounding soil quickly. Amending the backfill soil frequently does nothing more than provide a favorable environment for roots that discourages extensive growth. Plants without extensive root growth are more susceptible to injuries due to stresses such as drought, moisture excesses, insects and diseases. Addition of fertilizer to the backfill soil is usually not necessary.
Backfilling around plants is best accomplished when air spaces are minimized to avoid problems such as soil collapse and roots drying. Careful backfilling will help improve the contact between the roots and soil. Root balls that are covered with burlap can be partially backfilled before loosening the wrap. After folding the wrap back, it can be completely covered with the remaining soil. After backfilling, the soil can be thoroughly watered to improve the contact between soil and roots. Future irrigations will be aided by the formation of a basin above ground. This can be done by forming a berm of soil in a circle around the plant roughly the same circumference as the planting hole. This basin allows irrigation water to gather above ground to insure more thorough wetting of the soil.
Postplanting care. The most important need for the first growing season is water. Most recently planted material require 1-1.5 inches of irrigation or rainfall water per week during the growing season. Water is equally necessary during dormant seasons although the volumes needed are less. Required water can be more effectively applied in one or two thorough applications than in several small applications.
It is usually not necessary to prune nursery grown plants at planting time unless for shaping purposes. If adequately watered, most plants are able to support the top growth. Any top growth that dies back in the first year can be pruned away the following spring.
In general, trees and shrubs need not be staked at planting except when it's necessary to anchor the roots, protect the plant from mechanical damage or the plant is unable to stand without support. Staking trees usually results in trees that are less stable when the stakes are removed making them more susceptible to injuries. When stakes are used, it is best to limit their use to one or two seasons.
Transplanting trees and shrubs. It is occasionally necessary to transplant desirable or valuable trees and shrubs from one location to another. Most homeowners can successfully transplant small to medium sized plants, (up to 6 feet tall) but large trees are often best left to professionals. The principles of planting such plants are similar to planting nursery grown material. Plants with shallow, fibrous root systems usually transplant easier than those with a few large roots. Transplanting shrubs is usually more successful than trees and transplanting deciduous plants is usually more successful than evergreens.
Generally, the more roots that can be transplanted with the plant, the more successful the planting will be. One method to increase root volumes is to root prune the plant in advance of transplanting. Ideally, root pruning takes place at least 4-6 months before transplanting and involves cutting around the plant with a spade at the circumference of the desired root ball and to the depth of the spade. This will sever the roots, usually encouraging the plant to grow new roots within the root ball thereby increasing the number of roots transplanted.
Transplanting is best accomplished when the plant is not growing. For deciduous plants and broadleaf evergreens, early spring is usually best. For conifers, early fall or early spring works well. It's important to remove a soil ball along with the plant to minimize the impact to the roots. Dry soil can be watered to help the soil remain in a ball. For best results transplants should be out of the ground for as brief a period as possible. If a plant must spend any length of time out of the ground prior to replanting, the root ball can be wrapped in burlap or placed in a large container, watered thoroughly and stored in a shady location.
Few projects around the home are more rewarding than successfully establishing a landscape planting of trees and shrubs. Whether it’s a plan designed by a landscape architect or the homeowner or simply a planting of a single plant, a successful planting is usually the result of careful planning. Consideration of the planting site, plant selection, planting methods and post-planting care are vital to success.