Trees for urban areas and the soil to use

Trees for urban areas

and the soil to use

Can you put a price tag on a tree? It is easy for those that sell timber for building, paper or for other targeted industries, but what is a living tree worth? When you look at all the benefits, how is it possible to put a cost on a tree?

Besides supporting our wildlife, providing oxygen and clean air and stabilising soil, trees have also been proven to provide mental benefits, improving moods and acting as a calming element.

Many people, including plenty of landscapers, plant trees too deep and this almost always results in damage to the tree (in fact, it is often a fatal mistake). This is easy to remedy if you know what to look for and how to plant correctly.

No matter their container size or type, all trees need to be planted at the right depth for their root system. Read on and you can avoid one of the most common tree-planting mistakes.

How deep is too deep when planting a tree?

The measure for tree planting depth is the tree’s root flare. Sometimes called trunk flare or root collar, this is the area just above where the topmost roots emerge from the trunk.

Confusingly, there is not always a flare here, meaning that some trunks, especially on young trees, may look like a straight cylinder. If you don’t see a flare, don’t worry. Look for the tops of roots and for the slight change in surface appearance where the bark tissue ends and root tissue begins.

First, you will need to release your tree’s root ball from its container or wrapping. Gently lay the tree on its side, being sure not to damage any

Mulch is vital to help hold water in the soil, regulate soil temperature, and to suppress weed growth.

Article by Richgro

branches, and work the container or wrapping off. Do not pull the tree out by its trunk!

Using your fingers or a smooth tool, scrape back the soil from the top of the root ball, untangling and arranging any small roots you disturb. When you have cleared around the circumference of the trunk and exposed the root flare, stand your tree up and measure from the root flare to the base of the root ball. (You don’t want the root system exposed, but just covered by the root ball soil.) This is the maximum depth to plant your tree. Measuring with the tree upright ensures that a loose root ball won’t compress down further after planting.

Digging the planting hole

After you have located where your tree is going to be planted, dig a round planting hole that is the depth you’ve measured on your tree, and two to three times as wide.

To ensure the tree lives a full life, it is extremely important to ensure the soil in your planting area is fortified with organic matter. Mix in a good quality soil-mix into the top 10 centimetres of soil where the tree is to be planted. A mix such as Richgro Tree Planting Mix has been formulated for West Australian soils, with ingredients like fully composted organics, small percentage of clay, added wetter and Osmocote 8-9 month release.

If you have dug too deep, add a layer of soil back into the planting hole and compact it with your foot. You want a stable soil base that won’t sink and bring the tree planting level down with it.

Installing the tree

Carefully lift your tree into position in the centre of your hole (hold it by the root ball as you do this, not by the trunk). Rotate it to make sure the “front” view is right from where you will see the tree. You’ll want to choose the angle that displays the best-looking branch structure.

Gently pack the backfilled soil with your foot as you fill. You don’t need to stamp hard; you just want to stabilize the backfilled soil so its level doesn’t drop and expose the root ball when you water the tree in.

Stake if needed

Tree stakes are commonly used for new trees, but they are not always necessary, but essential for windy sites as damage may occur when out on site.

Watering your new tree

In hot and arid climates, it is always a good idea to shape your backfilled soil with a rounded lip or berm just outside of the root ball. This makes a shallow, dish-like centre that encloses the root ball, and which will hold water while it percolates into the soil. Providing enough water to new trees is important, as it prevents damage to your tree from drying out. If the correct soil is used, this will hold onto necessary water and nutrients in the early stages of the tree’s life.

Mulch

Mulch is vital to help hold water in the soil, regulate soil temperature, and to suppress weed growth. Remember to regularly replenish organic mulch as it breaks down into the soil and expand your mulch ring as the tree’s crown (and root system) spreads. The amount required will depend on the size of the tree and the depth (usually 100mm) of mulch required. Again, choose a fully composted Australian Standard mulch to avoid any issues of disease and taking away the trees nutrients.

Recommended tree varieties for urban areas include:

1. Frangipani white 2. Jacaranda blue 3. Japanese maple 4. Hong Kong orchid tree 5. Poinciana 6. Yellow flame tree 7. Broad leaved paperbark 8. Black genoa fig tree 9. WA Christmas tree 10. Crepe myrtle tree.

These varieties can be successfully grown in Perth, most of the South West and throughout Western Australia. They are hardy and once established, need very little care and attention and encourage bird and wildlife.