Buying an advanced or semi-mature tree means you don’t have to wait for a sapling to grow. You get instant shade and a great head start on that green and leafy canopy you’re after. Of course, all these benefits don’t come cheaply, and you also need to factor in the cost of delivery. But for special situations, such as quickly greening up a bare yard, or replacing an old tree that’s come to grief, an advanced specimen can be a great investment.
Buying a ready-grown tree
Advanced-tree nurseries specialise in stock 10-15 years old, usually grown in large black plastic grow-bags. The tree heights vary according to the species and age, but trees of 3-4 metres are ideal for home garden use and retail for around $850. Much taller specimens are available, too, but these can cost several thousand dollars and are more commonly used in large civic landscaping projects, such as parks or housing developments.
Before you head off to the nursery, draw a rough sketch of your garden, showing the position of the house. This will help the nursery attendant to advise you on the best size and shape of tree for your situation.
When you’re choosing a tree at the nursery:
- Check the foliage to make sure it’s green and healthy.
- Inspect the trunk to ensure it’s straight and without wounds.
- Pull away the side of the plastic growing bag and inspect the root ball to make sure it isn’t pot-bound.
- Check that the nursery can deliver to your home - transporting advanced trees can be quite tricky.
*TIP: As well as growing large trees, advanced-tree nurseries will often remove mature specimens from existing gardens and then resell them ‘second-hand’. Not all trees are suitable for removal, but when you’re demolishing or extending, it may be worth finding out if you’ve got a specimen you can sell.
Planting a mature tree
An advanced tree needs a planting hole around twice the size of the root ball. To plant where an old tree has been removed, you’ll first need to get the stump ground out (most tree-lopping companies provide this service). Then you’ll need to dig out as many of the old roots as possible.
They strip the soil of nitrogen when they decompose, and that means there’s less available for your new tree.
- As you dig, keep measuring the depth of the hole against the depth of the root ball - remember, you can’t keep lifting it in and out to check. Rough up the sides of the planting hole to help the new roots penetrate into the adjacent soil.
- If the soil is a heavy wet clay, dig an additional drainage hole in the centre of the main hole. Fill the hole with gravel, then cover with a piece of hessian. This will prevent your new tree from drowning in a water well.
- For backfilling, mix the removed soil with some mushroom compost in a ratio of about 50:50. Shovel in just enough so the top of the root ball will sit level with the ground.
- Cut away the sides of the planter bag to expose the root ball, then trim through any roots which are circling the ball.
- Carefully lower the tree into the planting hole.
- Backfilling the planting hole with the remaining soil and water thoroughly. Scatter some controlled-release fertiliser and a light covering of mulch. Over the next few weeks, water at least every day or two to keep the soil constantly moist while the tree is settling in.
- In windy areas, stake the tree to keep the root ball steady. Use about three stakes, positioning them just outside the root ball, and tie with hessian webbing. After about nine months, the hessian will have rotted and the stakes can then be removed.
*TIP: To make watering easy, create a small catchment area around the root zone of the tree. Build up a low bank of earth to direct the water inwards, or try a Greenwell - a circular plastic ring which is suitable for smaller trees.