Planting depth — the root collar rule
Quick answer. The point where the trunk flares out into the roots — the root collar — belongs at or very slightly above the finished soil surface. Not below it. This applies to trees, shrubs and palms alike, and it is the one planting decision that is almost impossible to correct once the plant is established.
Why burying the collar causes harm
The trunk and the root system are different tissues with different tolerances. Root tissue functions in soil; trunk tissue does not. Soil packed against a buried trunk stays damp against bark that is not adapted to constant moisture, and the collar is also where a plant is most vulnerable to decay entering.
The damage is slow. A tree planted too deep does not fail in the first season; it declines over years, and by the time the decline is obvious the cause is buried and invisible. Growers commonly respond by feeding and watering more, which does not help and can make the situation worse.
Two ways plants end up too deep
First, planting too deep at the outset — usually from digging the hole deeper than the root ball. Second, settling: a hole dug deeper than the root ball and backfilled will compress when watered, and the plant sinks. This is why the depth rule is expressed as "no deeper than the root ball" rather than as a measurement.
A third and less obvious route is mulch. Mulch piled against the trunk after planting has the same effect as burying the collar, and it is applied by people trying to help.
Container plants specifically
Check the collar before planting rather than assuming the top of the potting medium marks it. Nursery plants are sometimes potted deep, and if you plant to the existing soil line you inherit that error and add your own. Scrape the surface back until you find the flare.
Palms deserve a specific note. Palms do not produce new roots from a buried stem the way some other plants do, and a buried palm stem is a decay risk rather than an opportunity. Plant at the depth the palm grew at. This guide covers planting depth only — for anything concerning Red Palm Weevil, see the dedicated safety notices in this Knowledge Centre. Fertilisation and planting depth neither treat nor prevent that pest.
Sources
FAO — Fertilizer and Plant Nutrition Bulletin 16, Chapters 4 and 5. Accessed 27 August 2026. Root-collar planting depth is horticultural and arboricultural common ground rather than a finding from this source, and is labelled as such. No dimension is stated.
Last reviewed 27 August 2026