Landscaping - How to select a Tree

If you want to plant a tree in your garden, these are points to consider when selecting the tree, purchasing and then ultimately planting it.

Selection of suitable trees

Space. In order to develop symmetrically and grow without causing you ongoing maintenance problems, trees should never be located closer than 2 meters from any boundary wall and 4 or 5 meters from any building or structure. Trees planted closely against structures will always grow (lean) away from them, causing the tree to become asymmetrical and even unstable; besides this, you will continually have to contend with branches rubbing against the walls and windows.

Root systems. Certain trees (such as Ficus species) have particularly invasive or strong root systems and should under no circumstances be planted near ponds, swimming pools or underground drainage services as they can cause serious structural damage to these items; when in doubt check with the nursery who is selling you the plant, or research the plant on-line. Normally a tree's root system will extend 1.5 to 2x the diameter of the tree canopy. Tree roots will also impact what can grow directly below the tree.

Check what the ultimate or mature height of the tree is under local conditions. Ensure that it will have sufficient space to grow without damaging buildings, walls, or infrastructure.

Shading and screening. The purpose of the tree can be to provide the garden with screening, shade, or even dampen noise from traffic, however, if incorrectly placed in the garden can cause problems once the tree matures. This is particularly an issue with lawns, as the seasonal shade pattern from trees (and structures) can impact the condition of turfed areas.

Leaf and flower drop is of particular importance to properties that have swimming pools. Most local trees are evergreen although there are also some deciduous species. For the most part, the climate of the region is so moderate that even in winter the temperature does not drop enough for deciduous species to shed their leaves; however, if the tree is very exposed to cold wind, or after rain and wind the wind-chill factor may be sufficiently cold to cause leaf drop.

• Remember, just because a tree is evergreen that does not mean that it doesn't lose its leaves, however, this is a continuous process over the entire year and not limited to winter (as in the case of deciduous trees)

When buying a tree

Mechanical damage bark

Mechanical damage bark

Damaged stem and bark

Tree tie damage

Damage from tree tie

Irrigation spraying on stem

Stem rot - poor irrigation

Cornocarpus against wall

• The terminal leader is the dominant growth point of a tree, a good example would be a Pine tree, which has a single strong growth point at the apex of the tree, damaging this alters the physical growth characteristics of the tree, the same applies to all trees, even though they may not have a single terminal point, damage to this (these) will drastically change the shape and character of the tree over time. Ensure that the tree you select is symmetrical.

  • When choosing a tree, ensure the terminal leader of the plant has not been damaged, this can cause the tree to grow at an angle instead of upright, or produce numerous lateral branches - altering the shape.

• Check the stem and make sure there is no weeping sap or beetle holes in the trunk of the tree.

• Ring-barking or mechanical stem damage, avoid trees with any kind of open wounds to the stem (old or new), unless these have been treated correctly and have completely healed they can be points of entry for fungi and wood boring beetles.

• If the tree looks very large or disproportionate to the size of the container, this means that the tree has probably "rooted through" the container in the production nursery. Plants that are rooted through will have a much larger root system in the soil than what's actually in the container in the nursery.

  • When the tree is removed from the production nursery these in-ground roots are severed, this places the tree under severe stress as it will normally have a larger water demand than what can be met by its (now) small root system and will wilt. Avoid these types of plants if possible.

• If you are buying and having the tree delivered then mark/tag the tree to ensure that the one you have selected is the one that is delivered!

• Smaller trees are sometimes better than large full-grown ones; in most cases, a small tree will grow just as quickly if not faster, and will definitely acclimatize to transplanting far better when compared to a large specimen when planted in the ground.

Tree planting

• Planting holes, the ideal hole for a tree should be 1 meter, by 1 meter by 1 meter deep, this can however be tailored to suit the conditions of the site as well as the size of the plant that is to be planted.

• Depending on the container that the tree is supplied in, the tree should be laid on its side and then slid out of the nursery pot, it should then be placed directly into the prepared planting hole. For very large containers and trees the process may require 3 or 4 people.

• The tree hole should be backfilled with a 50/50 mixture of sweet soil and compost, this should be placed back into the hole and leveled off to a depth that corresponds with the height of the root ball of the tree. The tree should then be placed into the center of the hole; check that the soil level of the tree root ball is at the same level as the surrounding ground level. Do not plant the tree deeper than the top of the root ball soil level, this can cause stem rot.

• Use tree stakes to support and protect a tree during its first year. Do not use a rigid tree tie (such as wire), as this does not allow the plant to develop any strength of its own, as it relies on the strength of the stake for support. Flexible ties allow for support, but allow the tree to move and develop strength. Always check and loosen the tree tie from time to time, ties that are not loosened or removed can permanently damage the stem of a tree as the girth increases.

Tips

• The Damas Trees (Conocarpus erectus and Conocarpus longifolia). Although widespread in the region for its use as a screening and windbreak, the Damas Tree should be avoided at all costs, these are originally mangrove plants and have incredibly invasive root systems. It is very common to see damaged structural walls, damaged swimming pools and fouled sewerage and waterlines due to the roots. The trees are banned from in most residential developments across Dubai and Abu Dhabi for this reason.

• Do not use an edge trimmer around the base of a tree, this ring marking damages the stem and underlying tissue and can cause the plant to wilt and die.

• Do not place irrigation emitters directly against the stem of your new tree, besides leading to stem rot, as the water source is concentrated against the stem, it does not encourage the root system to develop more extensively, which leads to a poorer root system and a tree which may be blown over by strong wind.

• Gardening reference books are great and can provide a lot of useful information, however, where possible check the information against local information. The climate and geology of the Middle East are obviously not the same as that of Europe. This means that certain plants simply don’t grow here, others that do grow will adapt to local conditions and may look slightly different, have different flowering periods, and require different soil and irrigation conditions. Normally the height and growth habits of the plant will differ. Local, naturalized plants tend to have smaller leaves and dwarfed habits compared with their European and American counterparts.