Basic care when planting trees

Adopting appropriate planting methods is vital to ensure the health and longevity of trees. From choosing the ideal time to plant to soil preparation, watering and staking, we should bear in mind that good planting is an investment in the tree’s future, ensuring that it settles fully into its new space.

The months from November to April are the ideal time to plant your tree, a period during which plants remain dormant, which reduces transplant stress. The mild weather and low sun exposure are ideal conditions for trees to establish their roots, and the rainfall that recurs in these months helps to strengthen initial rooting.

Soil is the fundamental element for plant survival, as it holds the nutrients and water that allow plants to develop in good conditions. It should therefore be assessed to establish whether it is fertile or whether organic compost needs to be incorporated. Arid soils, such as decomposed granite, are unsuitable for planting, so this shortcoming should be corrected by applying Diaplant Professional Substrate, so as to supply all the nutrients the plant needs to establish. We recommend digging a planting hole with a diameter 1.5 to 2 times that of the rootball, so as to create loose earth that lets the roots penetrate the soil. The hole should be deeper than the rootball, but it must then be filled with soft, fertile soil so that, once in place, the rootball does not sit too deep. The plant’s root collar should be level with the soil surface, not buried, to allow good ventilation of the roots. Note: burying the trunk can kill the plant by asphyxiation!

To place the plant in the planting hole, it should preferably be carried by the rootball. Handling the tree by the trunk alone is a risk, as it can damage it. The wire mesh and hessian that wrap the rootball are biodegradable and so should not be removed. Taking them off can cause the rootball to fall apart, destabilising the root system and ultimately killing the plant. We therefore recommend placing the plant in the centre of the planting hole, paying particular attention to the rootball so that it does not sit too deep. The sides of the hole, between the rootball and the compacted earth, should be well firmed (with the help of watering in) to ensure the stability of the tree and prevent air pockets from forming.

Staking trees is an important practice that helps them grow healthily. Staking is essential straight after the tree is planted, as it gives young trees adequate support, helping them to withstand the winds or leaning that can naturally occur and so preventing them from falling. It also makes it possible to direct the tree’s growth in a more controlled way. This is particularly important in urban areas, where trees may compete for space with buildings and other structures. Stakes should be kept in place for 2 to 3 years, until the tree is able to support itself. The size of the stake should be in proportion to the girth size of the tree. For trees with a standard clear stem (stem height 200–220 cm), 250 cm turned pine stakes should be used, of which 100 cm will be buried. The stake should penetrate at least 20 cm into undisturbed soil. If the planting hole dug is too large, you should opt for longer stakes so that they reach firm ground. Always with sustainability in mind, Diaplant uses biodegradable coir rope to tie the trunk of the tree to the stakes.

In practice:

– Trees with a girth below 10–12 cm need 1 stake, placed on the side from which the strongest winds blow;

– Trees with a girth above 10–12 cm and below 20–25 cm need double staking, with the stakes in line with the trunk of the plant. Choose the best possible position to protect the plant from the wind;

– Trees with a girth above 25–30 cm need triple staking, with the stakes set in a triangle.

For aesthetic reasons, you can opt for underground anchoring, using the DIAPLANT K4 ANCHORING KIT. This system consists of 3 tempered steel anchors (110 × 55 × 4 mm), 3 galvanised steel cables 4 mm in diameter, 3 clamps, 1 strap 8 m long and 3.5 cm wide and 1 tensioner.

Fig. 1 – Diaplant K4 anchoring kit

In addition, if the plant is going to be exposed to strong sunlight, we recommend wrapping the trunk in biodegradable hessian during the summer months, for at least 2 years, until the plant has established in its new space and tolerates direct sun. The flow of water through the sap-conducting vessels works as a cooling system, protecting the trunk from overheating. Until the tree is established, however, this flow is lower, so it is advisable to compensate by protecting the trunk. Vulnerability to sun exposure varies with the roughness of the trunk, so species with smoother trunks are more prone to sunscald.

Fig. 2 – Triple staking (left) and double staking (right). The tree on the left has a rough trunk and does not need biodegradable hessian wrapped around it. By contrast, the trunk of the tree on the right has thin, delicate bark, and wrapping it in biodegradable hessian is advised to protect the trunk from sunscald during the hottest months.

During the first three years after planting, trees need extra care with watering until they establish in their new space. To that end, a basin the diameter of the rootball should be dug around the tree. In addition to automatic drip irrigation, supplementary hand watering is advised, once or twice a week, during the hottest months and the trees’ adaptation period, according to the needs of the species and the weather conditions. To make sure the water reaches the whole rootball, it is better to deliver a larger volume of water in one go than to water several times with less. It is important to stress that waterlogging can kill the tree by inhibiting the exchange of oxygen between soil and roots. It is imperative that watering genuinely matches the plant’s needs.

Another major factor is feeding. Supplementing trees with slow-release NPK fertiliser (nitrogen, phosphorus and potassium) is strongly advised. In this way the plant takes up the essential nutrients when it needs them, ensuring more efficient and balanced nutrition. The result will be faster, more vigorous growth. In addition, adequate feeding strengthens the trees’ immune system, making them more resistant to pests and diseases and helping to improve water retention in the soil. We recommend applying fertiliser in the following quantities:

– Girth 10–12 cm – 200 g;

– Girth 12–14 cm – 300 g;

– Girth 14–16 cm – 400 g;

– Girth 16–18 cm – 500 g;

– Girth 18–20 cm – 600 g;

– Girth 20–25 cm – 700 g;

– Girth 25–30 cm – 800 g;

– Girth 30–35 cm – 900 g;

– Girth 35–40 cm or above – 1,000 g.

The root cutting inherent in lifting the tree causes an imbalance between the root system and the crown, since the roots lose the capacity to ‘feed’ the full leaf density of the top growth. Pruning helps to restore this balance, reducing the amount of water the roots need to absorb and so minimising transplant stress.

It is a fact that post-transplant recovery and development are better in pruned trees than in unpruned ones. By the end of the first growing season, the crown has grown back almost to the size it had before pruning, and in the second season it overtakes the growth of unpruned transplanted trees. Pruning is carried out only on branches with 1 or 2 years of growth, so it compromises neither the structure nor the appearance of the crown.

Figure 1. Trees prepared for planting on site. The rootballs are wrapped in hessian and biodegradable mesh, which keeps them compact and avoids potential injury from sunburn.

We are always on hand to advise you on planting your trees. Get in touch with us!

Original article

This article was first published on the diaplant.pt blog.