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This is the one rule that decides whether your plant stands up in ten years. Eucalyptus produces a strong central root very early, and that root resents circling in a pot. A plant sold in a one-gallon pot at eighteen inches (45 cm) tall will almost always overtake a five-gallon plant bought the same day, and it will anchor itself far better. The bigger plant spends its first two seasons trying to escape a root ball that has already turned in on itself.
When you tip a candidate plant out of its pot, look for a root system that is still pale and still exploring, with soil visible between the roots. If the outside of the root ball is a solid mat of tan roots wrapping around the base, put it back. Root pruning helps with many shrubs; with eucalyptus it sets the plant back hard, because the deep anchoring roots are exactly the ones you would be cutting.
Growth rate makes this easy to accept. A young eucalyptus planted into decent ground routinely puts on three to six feet (0.9-1.8 m) in its first full season and can double that in warm climates with summer rain. Whatever head start a larger nursery plant appears to give you will be gone within one year, and the small plant will be the one still standing after a winter gale.
Site, soil and drainage
Full sun, all day. Eucalyptus in part shade stretches, leans toward the light and produces thin stems that flop. Six hours is a bare minimum and eight or more is what the plant actually wants. Shelter from the coldest wind helps a young plant establish, but do not tuck it into a still corner: a plant that never feels wind never builds the trunk taper it needs.
Drainage matters more than fertility. These plants tolerate poor, thin, stony ground cheerfully and rot in ground that stays wet through winter. If water stands in the planting hole after rain for more than an hour, plant on a low mound six to twelve inches (15-30 cm) above the surrounding grade instead of digging deeper. A deeper hole in heavy soil is a sump, not drainage.
Do not enrich the planting hole. Compost and fertilizer mixed into the backfill encourage the roots to stay in that comfortable pocket instead of pushing out into the surrounding ground, and they push soft, fast top growth on a plant that is already too fast. Backfill with the soil you dug out, break up any clods, and firm it with your hands rather than stamping it.
| Site factor | What eucalyptus needs | What goes wrong otherwise |
|---|---|---|
| Sun | Six to eight hours minimum, unshaded | Thin drawn stems that lean and flop |
| Drainage | Free-draining; mound in heavy soil | Root rot and sudden collapse in a wet winter |
| Soil fertility | Ordinary to poor; no enriched backfill | Soft, over-fast growth and weak anchorage |
| Soil pH | Tolerant, roughly 5.5-7.5 | Chlorotic yellow leaves above about 8.0 |
| Wind | Open air, some movement from day one | No trunk taper; the plant never self-supports |
| Space overhead | Assume tree height unless you cut it back | Roof, gutter and power line conflicts in a few years |
How to set the plant
The mechanics are simple, and the mistakes are all in depth and staking. Plant at the depth the plant grew in its pot, no deeper, and resist the urge to give it a tall stake and leave it there.
- Dig wide, not deep Open a hole two to three times the width of the root ball but no deeper than the root ball is tall. Loosen the sides with a fork so the walls are not glazed. The plant should sit on undug ground so it cannot settle below grade later.
- Tease the surface roots only Slide the plant out and gently loosen just the outer quarter inch (5 mm) of roots with your fingers. Do not wash the soil off, do not slice the root ball into quarters and do not shorten the strong central roots.
- Backfill and water in Return the native soil in layers, firming with your hands. Water with five gallons (about 20 liters) delivered slowly, which settles the soil around the roots far better than treading it does.
- Stake low or not at all If the site is exposed, use a single short stake driven at an angle, tied about a third of the way up the stem, and remove it after one growing season. A tall stake at head height guarantees a plant that cannot stand alone.
- Mulch, keeping the stem clear Two to three inches (5-7 cm) of coarse bark or wood chip over the root zone, pulled back two inches (5 cm) from the stem itself. Mulch touching bark holds moisture against it and invites rot.
Once a eucalyptus has been in the ground for two seasons it will not move successfully. The deep anchoring roots are lost in the lift and the plant almost never recovers. Choose the site as if it is permanent, because for this plant it is.
Decide now what you want it to be
Most people buy eucalyptus for the round, silvery, coin-shaped juvenile leaves. Left alone, the plant outgrows that phase: it switches to long, narrow, dull green adult leaves, usually somewhere between its second and fourth year, and it becomes a tree. If you want the silvery foliage, you are committing to cutting the plant hard every year or two, which is covered in the pruning guide.
That decision changes where you plant. A plant kept coppiced to a low stool needs a spot roughly six feet (1.8 m) across and can sit in a border. A plant allowed to run up as a tree needs to be a long way from the house, and you should assume it will get large and that its root plate stays shallow and wide rather than going deep. Shallow-rooted fast-growing trees are the ones that come down in storms.
There is no way to have both from one plant. A tree that has gone over to adult foliage does not go back except from cuts made into older wood, and by then you are dealing with a trunk, not a stem.
What to write down on planting day
Record the planting date, the size of the plant, and exactly where it is relative to a fixed feature such as a fence post or a corner of the house. Fast-growing plants make you forget how small they started, and a year-one measurement is the only honest reference you will ever have for how quickly this plant grows on your ground.
Also note whether the plant still had juvenile round leaves at planting and whether you staked it. When you come to prune, the date the stake came off and the date the foliage started to change are the two facts that tell you whether the plant is on schedule or racing ahead of it.