Digging a tree planting hole
Quick answer. Dig the hole wide and no deeper than the root ball. Roots spread outward far more than downward, so width is what helps and depth is what harms: a hole dug deeper than the root ball allows the tree to settle after watering, leaving the root collar buried. Loosen the sides so roots can leave the hole. Backfill with the soil you removed, not with imported rich compost.
Why width and not depth
A young tree's roots need loose soil to extend into, and they extend laterally. A wide, shallow hole with roughened sides gives them that. A narrow, deep hole gives them a shaft — and if the sides are smooth and the surrounding soil is compacted, roots reaching the wall turn and circle rather than crossing it.
The depth rule is mechanical rather than biological. Soil placed under a root ball is disturbed soil; it compresses when watered, and the tree sinks. A tree planted level that sinks two centimetres has a buried collar, and a buried collar is a long-term problem that is difficult to correct once the tree is established.
Why not to enrich the backfill
This is the point most often got wrong. Filling a hole with rich imported compost in the middle of poor surrounding soil creates a pocket that differs sharply from everything around it — in texture, in water-holding capacity and in drainage. Water moves differently across that boundary, and roots that find the pocket comfortable have less reason to leave it. The result is a root system shaped like the hole you dug.
FAO's description of sandy soils is worth holding here: they are poor in nutrient reserves and have low water-holding capacity, but they provide favourable conditions for root growth, aeration and drainage of surplus water. The soil around your hole is not the enemy. Improve fertility across the whole planting area over time instead of concentrating it in one pocket.
In Kuwaiti conditions
FAO lists among the special problems of arid soils that there is sometimes little usable profile depth because of hardened lime crusts in the subsoil. Check for a crust or hardpan before you dig, because a hole that ends on an impermeable layer becomes a basin that holds water against the roots — the opposite of what the site appears to offer. If you find one, the planting decision changes: break through it, or plant higher, or choose a different position.
Do not add fertiliser to a planting hole. Roots at planting are damaged and are not yet taking up nutrients efficiently, and fertiliser placed in direct contact with them can injure them. Feeding belongs after establishment, not at planting. This guide states no dimensions in centimetres because the correct hole is measured against the root ball in front of you, not against a number.
Sources
FAO — Fertilizer and Plant Nutrition Bulletin 16, Chapter 4 (soil texture and fertility; sandy soils), Chapter 5 (arid soils: usable profile depth and lime crusts), Chapters 3 and 7. Accessed 27 August 2026. Planting mechanics are horticultural common ground and are labelled as such; no dimension, rate or quantity is stated.
Last reviewed 27 August 2026