Planting trees

The right time to plant a field-grown tree is during the dormant period.
For deciduous trees, this is from the time the trees have shed their leaves and hardened off until sap flow starts again in spring. In Western Europe, balled trees can generally be planted from mid-November to the end of April, but this depends greatly on climatic conditions and the tree species. Temperature in autumn and spring plays an important role, and not all trees shed their leaves at the same time. The same applies in spring to the time at which the leaves develop. The planting season for evergreen and coniferous trees is generally slightly longer than for deciduous trees. Container-grown trees can be planted all year round. These are generally smaller-sized trees.

When to plant trees?

Autumn is the ideal time to plant trees. The establishment of the tree in its new location is determined by the extent to which the tree develops new fine roots. This depends on various factors, such as soil moisture content and soil temperature. In autumn, these factors are generally favourable. The soil temperature is still sufficiently high for trees to develop new fine roots after transplanting and before winter sets in. The increase in the number of fine roots makes it easier for the tree to take up water the following spring. The trees suffer less from transplanting stress and will resume growth more quickly. Planting trees in autumn is therefore ideal, but not always feasible in practice.

Planting trees: Complete step-by-step guide

This step-by-step guide explains how to plant trees efficiently and effectively. From digging the planting hole to pruning after planting, we cover everything you need to know to ensure that newly planted trees establish healthily and can grow vigorously in the future. This guide provides the information needed to plant trees successfully.

1. Planting trees: digging the planting hole

Dig a generous planting hole with a diameter 1.5 to 2 times the diameter of the root ball. For example: if the tree has a root ball 60 cm in diameter, the planting hole should have a diameter of at least 90cm, but preferably 120cm. Make the planting hole slightly less deep than the height of the root ball. To allow oxygen exchange, the tree must on no account be planted deeper than it stood in the nursery! For large trees, allow for the tree to settle due to the weight of the root ball. This can compact the soil beneath it, especially if the soil has not yet settled properly, for example on new-build projects (fig.1). Loosen the base of the planting hole thoroughly to a depth of 1 spade, and loosen the sides if necessary. The sides of clay or loam soils can become smeared during digging, especially when wet. Loosening them with a spade allows the roots to grow through more easily. Mix any new soil with the existing soil. Sometimes the hole is filled with garden soil. Mix this with the existing soil at the bottom so that the roots can grow out of the planting hole more easily.

2. Planting trees: anchoring trees

A newly planted tree must be anchored to prevent it being blown over. The most commonly used anchoring method is above-ground anchoring with two or three stakes. Two stakes are sufficient for smaller trees, up to a trunk circumference of 25-30cm. Larger trees, with a trunk circumference from 25-30cm, should preferably be planted with three stakes. Choose stakes of a length and thickness appropriate to the size of the tree. For standard trees, with a clear stem height of min. 200 cm, use tree stakes of 250 cm. 100 cm goes into the ground and 150 remains above ground. For a shorter stem length, choose a shorter stake.

Using a soil auger, drill 2 or 3 holes in the ground immediately beside the root ball, opposite each other or in a triangular arrangement, and drive the tree stakes firmly into the ground. At least half of the stakes should be below ground. When using 2 stakes, take account of the prevailing wind direction. In the Netherlands, this is south-westerly. In that case, position the stakes to the south-east and north-west. Backfill the planting hole with soil. Soil life can be stimulated by mixing an organic soil improver or well-rotted compost into the soil. Firm the soil in the planting hole well as you go. Connect the tops of the three tree stakes with battens to form a sturdy structure.

This is not necessary when using two stakes. Place a tree tie around the trunk from each stake and nail it to the tree stake. The tree ties should not be loose, but neither should they be under tension. After approximately 3 years, the tree stakes will have deteriorated and the above-ground part can be removed. The tree will have established itself sufficiently to continue growing without support.

3. Planting trees: creating a watering rim

New trees must receive additional water for at least the first two years. The amount depends on the weather and the tree species. Use a watering rim made of soil or plastic to ensure that the water soaks properly into the root ball. The diameter of the watering rim should be the same as that of the root ball, so that water also penetrates the root ball (figure 5). In dry weather, check the moisture level beside the root ball 1 x per week and water as required. When water is needed, give a large amount at once rather than a little every day. Soil moisture can be checked, for example, using a soil probe or by pushing a spade into the ground. Keep the root balls moist throughout the growing season, but not soaking wet! Trees can also die from too much water; there is then too little oxygen in the soil and the roots rot. In addition to a watering rim, there are other methods of watering trees.

Download our planting instructions as a PDF

Pruning after planting

Healthy trees have a natural balance between crown and roots. This is disrupted when the tree is lifted, as every tree inevitably loses part of its roots during lifting. As a result, the roots can supply less water to the crown, causing stress. The tree will respond by producing fewer and smaller leaves, thereby reducing its leaf area. If the water shortage is too great, the tree will even shed wood from the crown, with the risk of impairing its habit. Watering is therefore necessary during the first two years, but this alone is often not enough. During prolonged warm periods or at extremely high temperatures, the foliage may dry out while the root ball is still moist. The root capacity is then simply insufficient to transport the required amount of water to the crown. In that case, giving more water is not an option and only has adverse consequences, such as oxygen deficiency and root rot. The only solution is to reduce the water demand and prune the tree. Preferably immediately after planting, to prevent the trees from suffering severely during peak periods. During the first two years, the crowns will therefore have somewhat less volume, but the trees will suffer less from stress, establish more quickly and develop better afterwards.

Pruning is carried out in one- or two-year-old wood. The thick wood in the crown must be retained. It contains stored nutrients that the tree needs to develop new roots. It is not necessary to prune all the one- and two-year-old wood from the tree. Trees with a lot of wood in the crown require substantial pruning, whereas trees with little wood in the crown, such as an Ailanthus, are pruned minimally. To avoid adversely affecting the tree’s habit, it is advisable to retain the terminal buds and remove only lateral shoots.

Read the interview with Cees van Casteren here about pruning after planting.

Trunk protection against sun scorch

Unfortunately, it is occurring increasingly often: cracks in the trunk caused by overheating. Water transport in the trunk normally protects the bark cells against overheating, but after planting less water is transported to the crown and this cooling system does not work sufficiently. The trunk is therefore at risk of sun scorch. The setting sun is the main culprit, as it shines directly onto the trunk and can heat the cells so intensely that they are damaged. This is why sun scorch is usually visible on the west side of the tree.
Trees with smooth, thin bark in particular are highly vulnerable and must be protected. This can be done by wrapping the trunk with coconut or reed mats. Trees with rough bark and trees that are branched from the base are less vulnerable and usually do not require protection.

Please note: jute was often wrapped around the trunk in the past, but practice has shown that this can have adverse effects. Because the jute is wrapped tightly around the trunk, heat can build up underneath it. The temperature can then rise considerably, with negative consequences for the bark and the rest of the tree