Planting Your Advanced Tree

An advanced tree arrives with years of careful growing already behind it. The planting itself is straightforward — a morning's work for most sizes — but the decisions you make in that morning shape the next several decades. This guide walks through the method we use on our own farms, step by step.

The whole process is captured in the three-step diagram above: dig the hole to the right proportions, set the tree with its root flare at ground level, then backfill, water in and mulch.

Step one: dig wide, not deep

Roots establish outwards, not downwards. The single most common planting error is a deep, narrow hole; the most useful thing you can do for a new tree is give it loosened soil to grow sideways into.

Dig the hole at least 10 per cent wider than the container — and where space allows, loosen or cultivate the surrounding soil to two to three times the width of the rootball. Depth is a different matter entirely: the hole should be never deeper than the rootball — the tree must sit on firm, undisturbed ground so it cannot settle lower over time.

The list below gives the container dimensions for each size — the figures are the pot or bag itself, not the hole. A 100 L bag, for example, is 50.6 cm wide and 52.8 cm deep. Take your container's dimensions from the list, then dig the hole at least 10 per cent wider than the container, and no deeper than the rootball.

• 30 cm pot — 33 cm wide, 30 cm deep
• 40 cm pot / 45L — 44 cm wide, 41.5 cm deep
• 50 cm pot / 70L — 55 cm wide, 41.8 cm deep
• 100L — 50.6 cm wide, 52.8 cm deep
• 150L — 66 cm wide, 55 cm deep
• 200L — 71.5 cm wide, 60.5 cm deep
• 300L — 88 cm wide, 63.8 cm deep
• 400L — 99 cm wide, 66 cm deep
• 500L — 122 cm wide, 66 cm deep
• 750L — 134 cm wide, 69 cm deep
• 1000L — 146.3 cm wide, 71.5 cm deep
• 2000L — 176 cm wide, 82.5 cm deep

In heavy clay, roughen the sides of the hole with a spade or fork so they do not glaze into a smooth basin that roots struggle to penetrate.

If you are unsure of your drainage, test it before you plant: dig a hole 300 mm wide and 300 mm deep, fill it with water and time it. If it takes more than six hours to drain, the position has a drainage problem — lay a 200 mm base of coarse gravel beneath the rootball, or talk to us about the site before going further.

Step two: set the root flare at grade

Find the root flare — the gentle widening where trunk becomes root — and make sure it finishes exactly at ground level, or a few centimetres proud in heavy or poorly drained soil. Buried flares invite trunk rot; exposed rootballs dry out. This matters enough that we have given it a guide of its own: see Planting Depth & the Root Flare.

Handle the tree by its rootball or container, never by the trunk, and check the tree is vertical from two directions before you backfill.

Step three: backfill with the soil you dug out

Return the native soil to the hole, blended through with a good compost, rather than replacing it with imported mixes. A hole filled with rich, light media in surrounding clay behaves like a pot sunk in the ground — roots circle within the comfortable pocket and water perches around them. Break up clods, backfill in layers, and firm each layer gently with your hands or boot heel. Firm, not compacted: the roots need oxygen as much as they need moisture. As you backfill, run water down the edge of the rootball so the soil settles against it and air pockets are expelled.

If you wish to improve the soil further, improve the whole planting area broadly rather than the hole alone, and keep solid fertiliser out of the hole entirely at planting time. The first feed comes later — an organic fertiliser at around six months, once the tree has begun to establish.

Step four: build a watering well and water in deeply

Shape the leftover soil into a low ring — a watering well — just beyond the edge of the rootball. Fill it slowly with water and let it drain, then fill it again. This first deep watering settles the soil against the roots and removes air pockets; no amount of light sprinkling later can substitute for it. For larger containers, expect to apply water generously: the entire rootball must be wetted through.

Step five: mulch

Spread coarse organic mulch about 75 mm deep across the planting area, keeping it 5–10 cm clear of the trunk. The shape you are after is a doughnut, never a volcano — see our mulching guide for the reasoning.

A note on our two climates

In the tropical north, the ideal planting window opens at the start of the wet season, when warmth and rain do much of the establishment work for you — though never plant into a waterlogged hole. At Ravensbourne elevations and similar cool districts, autumn and spring plantings establish beautifully; newly planted stock in frost-prone sites appreciates deep watering in the morning rather than the evening through winter.

From the growers — Water the tree thoroughly in its container the day before planting. A rootball that goes into the ground dry can shed water at exactly the moment it most needs to take it up. Overwatering into poor drainage, not underwatering, is what we see fail — which is why the drainage test in step one matters.

Every tree we grow is available with planting advice specific to your site and soil. If you would like us to look over your planting plan, or to visit the estate by appointment, we would be glad to arrange it.