Planting an advanced tree: how to get it established - Plant Drop

Planting an advanced tree: how to get it established

What you are actually buying

An advanced tree is not a big version of a tube stock plant. It is a tree that has spent several years in a container, and what you are paying for is time: instant height, an established trunk, and a canopy that reads as a real tree from the day it goes in. What you are also inheriting is a container root system. Every root that tree owns is inside a cylinder of potting mix, and that cylinder dries out far faster than the ground around it.

The entire job of the first two years is converting that container root ball into a field root system. Almost everything that goes wrong with advanced trees traces back to that one process being interrupted, usually by planting too deep, backfilling with the wrong material, staking too hard, or watering the wrong soil.

Plan the handling before delivery day. A 100L tree in wet mix is a genuine two person lift, and stock from 100L up through 200L and 400L usually needs a trolley, a tractor bucket, or three or four people and a plank. Have the holes dug and the access clear before the truck arrives. Trees that sit on a driveway in full sun for a week are already behind.

Dig wide, not deep

This is the single most useful thing on this page. Dig a hole two to three times the width of the root ball, and no deeper than the root ball is tall.

Roots move sideways, not down. Almost all of the fine feeder roots a tree will grow in its first few years sit in the top 300mm of soil, spreading outwards well past the canopy edge. A wide, shallow, saucer shaped hole with loosened soil around it is exactly what those roots want. A narrow deep pit is the opposite.

Deep holes also cause settling. If you dig below the root ball and backfill underneath it, that loose fill compresses over the following months and the tree sinks. A trunk that ends up buried 50mm to 100mm below its original soil line will hold moisture against the bark, and collar rot follows. Sit the root ball on undisturbed ground so it cannot drop.

  • The top of the root ball should finish flush with the surrounding soil, or slightly proud of it on heavy clay so water sheds away from the trunk rather than pooling.
  • Find the true root flare before you set the height. Potting mix is often mounded up the trunk in the nursery. Scrape the top of the mix back until you see where the trunk widens into roots, and use that as your level.
  • In clay, a spade glazes the sides of the hole into a smooth surface roots struggle to cross. Break the walls up with a fork before you plant.
  • Check the outside of the root ball for circling roots. On advanced stock there is usually at least one woody root running around the edge. Cut it cleanly, and make three or four shallow vertical slices down the side of the ball if it is heavily bound. Do not pull an advanced root ball apart.
  • Remove every strap, tie, tag and label from the trunk. Nursery ties left in place girdle trees a year or two later.

Do not improve the backfill

Backfill with the soil you dug out. Not compost, not potting mix, not bagged garden soil.

A hole full of rich, light material sitting in heavier native soil behaves like a bathtub. Water runs into it and does not readily move out, so the root ball stays wet. At the same time, the roots find no reason to leave a comfortable pocket and cross into denser ground, so they circle inside the hole instead of anchoring the tree. Then the organic matter breaks down over a year or two, the volume drops, and the tree settles.

The place for compost is on the surface, under the mulch, where worms will take it down and improve the soil across the whole root zone rather than in one pocket.

Backfill in layers, firming gently with your hands or the flat of a boot, and run water in halfway to settle the soil around the roots rather than compacting it hard. Air pockets against a root ball dry roots out.

The one exception is genuinely inert ground: builders' fill, rubble, or compacted subsoil scraped bare by machinery. That is a site problem, not a hole problem. Fix an area, not a pit, and improve a bed several metres across before planting.

Go easy on fertiliser at planting. Roots first. A gentle slow release product or a seaweed based tonic is fine; heavy nitrogen pushes top growth that the root ball cannot yet support.

Stake low, loose, and temporarily

Staking is meant to stop the root ball rocking in the ground. It is not meant to hold the trunk upright.

Trunks get strong by moving. Wind loading is what builds taper and reaction wood down low. A tree tied rigidly near the top of the trunk grows tall and thin above the tie and weak below it, and when the stake finally comes off it bends over, or snaps at the tie point in the first serious blow.

  • Use two stakes on opposite sides, driven into undisturbed ground outside the root ball, never through it.
  • Tie at roughly one third of the trunk height, and no higher than half. Low.
  • Use a wide flexible tie such as hessian webbing, in a figure of eight so the tie sits between the trunk and the stake. The trunk should still be able to sway.
  • On exposed or windy sites, three stakes or an underground guy over the root ball is better than one hard tie up high.

Then remove them. One growing season is usually enough, and most trees should be free standing within 12 to 18 months. Check ties every couple of months while they are on. Ties left to bite into an expanding trunk are one of the most common forms of avoidable damage on established stock, and by the time you notice, the damage is permanent.

This matters most with fast growing genera. Gum trees in particular put on canopy quickly, and a eucalypt held tight and high for two years is a tree waiting to fail.

Water deeply, and less often than you think

Two rules do most of the work here.

Water the root ball, not the garden bed. For the first summer the tree can only drink from the container root ball. You can irrigate the surrounding soil generously and still lose the tree, because that small volume of potting mix dries out first and fastest. Before you water, push a finger or a long screwdriver into the root ball itself, in through the top, and judge moisture there.

Give a large volume slowly, then leave it alone. A short daily sprinkle wets the mulch, the top few centimetres of soil, and nothing else, and it trains roots to stay at the surface where they will cook in January. A slow hose trickle over 20 to 30 minutes, a couple of full buckets tipped slowly into a soil basin built around the planting hole, or a loop of drip line around the root ball will do far more.

Stage What to do
First 6 to 8 weeks, warm weather Deep soak two to three times a week, checking the root ball each time rather than watering on autopilot.
Rest of the first summer Deep soak roughly weekly, more often in heatwaves or on sand, less on clay.
First winter Mostly rainfall. Check during dry spells, especially for evergreens, which keep transpiring all year.
Second summer Deep soak every one to two weeks. The root zone is now wider, so water a wider area, out past the canopy edge.
Third year onwards Supplementary water in extended dry periods only, for most species on most sites.

Two full summers is the honest figure for an advanced tree to be considered established. Larger stock from the 200L and above range takes longer, not less time, because there is more canopy demanding water from a root system that is proportionally no bigger.

Mulch, and keep it off the trunk

Mulch a circle at least as wide as the canopy, 75mm to 100mm deep, using a coarse chunky material rather than fine compost or lawn clippings that mat and shed water.

Leave a clear gap of a hand's width around the trunk. Mulch piled against bark holds moisture where the tree cannot tolerate it, encourages collar rot, and gives cover to borers and rodents. Mounding mulch into a cone up the trunk looks tidy and does real harm.

Keep grass out of that circle for at least two years. Turf competes hard for water in exactly the zone the tree needs, and line trimmer damage around the base of a young trunk is a common and completely avoidable killer.

Transplant shock, or a tree that is dying

Most advanced trees look unhappy at some point in their first season. That is normal, and the usual reaction, more water and more fertiliser, is often what finishes them off. Work out which one you are looking at first.

Transplant shock, usually recoverable Signs the tree is failing
Some leaf drop in the first weeks after planting, particularly older interior leaves on evergreens such as lilly pilly and magnolia. The whole canopy browns off quickly and the dead leaves stay attached, crisp and hanging.
Leaf edges scorching or browning on older foliage while new shoots keep coming. No bud movement at all through a full spring flush, on any part of the tree.
Smaller leaves and shorter growth than the previous season. Bark shrivelling, wrinkling, or peeling away dry on the main trunk.
A stalled period of several weeks with no visible growth. A scratch test on the trunk shows brown, dry tissue instead of green and moist just under the bark.
Dieback confined to the outer tips of branches. The root ball is either bone dry through the middle, or sour smelling and permanently saturated.

The scratch test is worth knowing. Nick a small sliver of bark with a thumbnail or the tip of secateurs, first on an outer twig, then lower on a main branch, then on the trunk. Green and damp underneath means living tissue. Work inwards until you find green; that tells you how much of the tree is still alive and whether it is worth pruning back to.

On heavy soils, drowning kills more new advanced trees than drought does. If a stressed tree's root ball is wet, stop watering, check that the hole is not sitting in a low point collecting runoff, and pull mulch back off the trunk. Adding water to a tree that is already waterlogged is the most common way people finish off a plant they were trying to save.

Notes by type

  • Deciduous stock. Maples, ornamental pears, elms, oaks, silver birch and crepe myrtle establish most easily when planted through their dormant period, because they get a whole cool season of root growth before facing a summer. If you are planning a driveway avenue, order for winter planting.
  • Evergreens. Lilly pilly, ficus, olive and magnolia never stop transpiring, so they still need checking through dry winter and spring weather in their first year.
  • Eucalypts and other natives. Gums and paperbarks are less tolerant than most of deep planting and rich backfill. Plant high, backfill with native soil, stake low, and remove the stakes early.
  • Japanese maples. The most likely of anything in the Japanese maple range to scorch in a first summer. Site out of hot afternoon sun and drying wind, and consider temporary shade cloth through a heatwave in the first season.
  • Citrus. Do not bury the graft union, and keep mulch well clear of it. Citrus is unforgiving about being planted low.

If you are pricing a job, it is worth comparing sizes rather than defaulting to the largest available. Semi advanced stock is easier to handle, easier to keep alive, and frequently catches up to larger stock within a few seasons because it establishes faster. Buy the biggest tree the site and the maintenance regime can genuinely support, not the biggest tree in the catalogue.

Orders are farm direct with a flat $99 delivery rate and a $399 minimum, across QLD, NSW, VIC, SA, ACT and WA. Browse the full advanced tree range or the feature trees if you are choosing a single specimen for a front garden.

Plants featured in this guide

Everything below is currently available farm-direct, with flat $99 delivery in QLD, NSW, VIC, SA, ACT and WA and a $399 minimum order.

Browse the full range: Advanced Trees · Super Advanced Trees 200L and Over

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