One of the benefits of being a landscaper is that you get to see firsthand how seemingly benign planting practices from the past can cause major problems to an owner’s property.
One of the most common problems we encounter with regards to this is the planting of trees too close to a home, perimeter wall, or other hard structure such as a pool.
When planting a tree, it's important to choose the correct position in which to plant it as it can be a difficult and costly process to transplant or remove incorrectly placed trees. In most cases, incorrectly planted trees will eventually cause damage to property, so the first step to countering this problem is to research your chosen tree and take into account its full-grown size, growth habits and aggressiveness of its root system.
As an example, the picture below shows a tree aloe (Aloe barberae) planted next to a house to enhance the entrance. This is a magnificent sculptural plant that enhances modern architecture. It grows up to 18m tall and branches out to give a spread of between 4-8m.
In this instance however, it was planted too close to the house and its branches are already squashed in the limited area. The trunk of this tree also swells with age and can grow to a diameter of 3m, which would then interfere with the house. In this case the homeowners should remove the tree - as it is still fairly young - and transplant it to a safer area.
Sometimes though, gardeners aren’t responsible for choosing the position in which trees grow. In the picture below, an exotic Celtis (Celtis sinensis) has self-seeded itself in a sheltered position next to a house.
The seed may have fallen from a neighbouring property, or, more likely, the seed was deposited in the droppings of a bird. The problem is not so much that the tree reseeded itself, but rather that the young sapling was not removed in time - weeds often find their way into gardens via bird droppings. In this case the tree was left to grow, and has now grown to a height of 4m and could very possibly be affecting the building’s foundation. For situations like this, contact a professional tree-feller and have the tree removed. Also ensure that the stump and large roots are removed as it is likely to send out new shoots if left.
Several trees also have large surface roots that could damage structures or paving. In the picture below, the roots of a Silk Floss (Kapok) tree (Ceiba speciosa) on a verge have not only lifted the curb, but have also cracked the boundary wall.
Again, this tree should be removed by a professional tree-feller, the curb re-laid, the wall repaired, and a new tree (with a non-aggressive root-system) planted.
A final mention on removing and replacing trees: it is often a sad experience to remove a large tree from a property, but it is far better to save yourself the resultant costs of damage to property and to plant trees that will prove non-aggressive and just as effective in years to come.
These are some of the trees we commonly see growing around Gauteng that self-seed next to walls and wan cause problems if not removed:
- Celtis sinensis (Chinese stinkwood)
- Jacaranda mimosifolia (Jacaranda, jakaranda)
- Ligustrum lucidum (Chinese wax-leaved privet)
- Melia azedarach (Syringa, sering boom)
- Morus nigra (Black mulberry, swartmoerbei)
- Solanum mauritianum (Bugweed, luisboom)
- Tecoma stans (Yellowbells, geelklokkies)
So, to sum up:
- Always research the full-grown size of the tree you wish to plant and allow room for it to grow and form a natural shape to avoid having to trim or completely fell it at a later stage
- Take into account the habits of the roots of your chosen tree
- Consider whether you have allowed enough space for a swelling trunk
For more information, read our Choosing a tree for your garden article, our Trees for small gardens article, or visit our plantbook.co.za website to browse and learn more about trees indigenous to Southern Africa.