Planting advanced trees
Soil preparation and drainage
Planting
Staking
Watering in
Aftercare
Pruning
Transplant shock
Reference

Planting advanced trees

How quickly and how well trees become established once they are planted is effected by the amount of stress they are exposed to before and during planting. Minimizing planting stress is the goal of effective planting.

Trees need to be thoroughly watered prior to planting to minimize water stress occurring; once in situ dry rootballs are very difficult to re-wet.

Soil preparation and drainage

Ideally soil preparation should be carried out well ahead of planting. Preparation could include incorporating organic matter into the soil to improve aeration and assist drainage of compacted soils, and to improve soil nutrient holding capacity. Specific preparation may be needed if the soil has an inappropriate pH or is lacking in certain elements. Similarly, contaminated soil or soil containing excesses of some elements will require amelioration prior to planting. Trees with a limited soil tolerance range may require very specific soil preparation to enable their requirements to be met.

Where drainage is a serious problem, particularly in built environments, then laying drainage pipes may be necessary before planting takes place.

The greater the area prepared for planting (soil volume) the better; tree roots will become established and continue to grow healthily in a good medium. Soil preparation is especially important with compacted soils.

Soils that have a distinct clay sub-soil should be treated cautiously especially if the soil profile does not have the depth to plant the tree in the existing topsoil. Do not mix topsoil and sub soil. It is very important to not disturb or dig into the clay sub-soil unless it is free draining and in most situations it is not. If topsoil is shallow, say less than 400mm, soil level will need to be built up to allow sufficient soil volume for newly planted trees to establish well in.

If importing soil on to the site its performance will need to be monitored over a growing season keeping in mind that most imported soils are poor in nutrients as well as being a source of weed seeds. It is better to incorporate compost through the soil to build up its profile rather than import soils.

In situations where the entire soil surface level cannot be raised, soil will have to be mounded around the trees individually so that they are not planted into the clay sub-soil. Once again the greater the soil volume the greater the chance the tree has to establish quickly and grow strongly. A common mistake made is to dig down into the clay sub-soil and replace this with 'good' soil; this will result in creating a sump which may collect water or at least produce a planting profile with poor drainage and provide low levels of soil oxygen.

For trees, the garden bed should be dug to a depth of at least 400mm and greater if the trees are larger. If there is solid clay in the profile at this should not be dug into or removed but the garden bed should be raised to accommodate the deep of the new trees being planted. The base of the holes should be firm if it is not the trees will sink which is undesirable.

A five way mix is best used to add organic matter to the garden beds.

Once the site has been properly prepared the tree planting can begin.

Planting

Trees should be planted immediately; exposure to air and light is harmful to fine roots and should be avoided. Place the tree in the hole.

Back fill hole with soil, firming it in to eliminate any air pockets. Ensure that the top of the root ball is level with the surface of the ground, or slightly higher as it will sink over time due to settlement of the rootball. Hill up the soil around the edge of the rootball, as shown in Fig 3, to create a levy to retain water. This is necessary to allow the water to penetrate the rootball and not simply flow straight into the soil around the rootball. It is very important that the levy is created, without it, it is difficult to supply the tree with enough moisture and is the most common result of stress and failure in large transplants.

Staking

Staking should only be done if absolutely necessary. Staked trees develop less calliper and a less robust root system than non-staked trees. A properly grown tree should have an adequate root to shoot ratio to anchor the tree firmly in the ground. Where vandalism is a concern then staking may be used to deter vandals. Where deemed necessary, trees should be staked at or below one third of their height. Ties and stakes should be removed after a year. Stakes have the potential to rub against trunks and cause scarring; ties left on too long may become embedded in the trunk and cause ring barking.

Minor movement will not be an issue if the trees are being grown as a hedge, and the trunks will not be seen however the landscape contractor should be prepared to stake the trees if there is major movement as continued movement will hinder establishment.

Watering in

Thorough watering in is crucial. Trees that have been used to a regime of daily watering in the nursery are susceptible to water stress once they are planted out and are no longer being watered so frequently. During the first few months, or for longer in the warmer part of the year, it is necessary to water the trees deeply and regularly.

Frequent light watering will encourage superficial roots that will be prone to drying out. A drip irrigation system is the most simple and effective means of watering trees thoroughly. Do not over water plants - in heavy soils that do not drain freely water may accumulate in the planting hole. This should be avoided by proper soil preparation before planting takes place.

Irrigation systems should be programmed to include separate watering for trees as their root profile is deeper than that of other newly planted plants and their water requirements are different, a common mistake especially when planted in lawn is to water the lawn rather than the trees.

Initial watering should be done by hand: by filling the watering well; It is recommended that you continually top up the well until it is thoroughly saturated and takes over an hour to freely drain away.

A drip irrigation system that only waters the trees is required on its own timer, the only way to judge how much water is required is to monitor the amount of water given and how much is retained in the rootball. The root ball and surrounding soil should be evenly moist through the whole profile of the root system. Investigate digging of the whole depth of the root ball is required after the contractor has applied what he considers adequate amount of water. This is the only true way to know if the trees are getting the right amount of water.

Aftercare

Mulch trees to limit evaporation of water from the soil and to minimize weed competition. Mulch in contact with the tree trunk may cause rotting; to prevent this, mulch should not be placed right up to the tree trunk. Over the surface of the rootball mulch should not be so thick that it prevents water from penetrating through it and reaching the rootball. Ensure that ties and stakes are not causing damage such as abrasion or ring barking.

It is very important to monitor drainage and irrigation once the tree is planted out this is especially important through the first growing season. Early recognition of potential problems can be resolved before they are detrimental to the health of the tree. If drainage is seen to be a problem we suggest and inspection pipe to the depth of the rootball be placed in a number of sites along the garden been for monitoring of drainage.

Pruning

The only pruning that should be done at time of planting is removal of damaged branches or branches that are an obstruction. A proper pruning saw or sectiers should be used.

Any other pruning should not be carried out until the tree is actually growing. The general rule is lighter pruning more often is better.

Transplant shock

These trees can go into shock and this varies in appearance from species. Some trees may totally defoliate. Defoliation is directly related drying out of the root ball. So the rootball should be keep evenly moist. If the trees show signs of yellowing from the center this is a sign that they are too dry. Once you do see the sign of transplant shock most of the damage is done and the tree may continue to defoliate. In some Genera such as Eucalypts and Confers, drying out can be fatal. Some species show sign of permanent wilt even though the tree is rehydrated this is because the petiole of the leaves had been damaged and while the tree has enough water it has the appearance of wilt it will only be the new growth, which has more upright leaves. (This is common in deciduous Genera like Pyrus)

The other common mistake is when a tree does defoliate it is the over watered (the reverse of the initial problem). The root ball must be rehydrated adequately then watered as normal. In instance when the trees has partly or totally defoliated it will require less than water than a fully foliated tree.

It is very important to monitor the progress of trees that are showing sign of stress as there may be a number of factors involved or those factor may change over the coarse of the period the tree is struggling.

In general trees will be well established once they have gone thorough their first growing season. However this does depend on the size of the tree transplanted. Larger trees will require longer periods of establishment maintenance.

Following these specifications will minimize planting shock so it is important the landscape contractor and maintained contractor adhere to them. If they have any concerns please speak to our Tree Depot representative at the time of delivery.

On site tree planting consultation by a qualified Tree Depot representative is also a service we provide.

Reference

Gilman, Edward F. 1997 Trees for the Urban and Suburban Landscapes. Delamar Publishers Albany New York USA

Harris, Richard W. Clark, James R. Matheny Nelda P. 1999 Arboriculture Integrated Management of Landscape Trees, Shrubs. And Vines. Third Edition. Prentice Hall New Jersey USA

Phillips, Leonard E JR. 1993 Urban Trees A Guide for Selection Maintenance and Master Planning. McCraw Hill New York USA