Question 1

How far do tree roots actually spread?

Accepted Answer

Much wider and much **shallower** than the popular image of a mirror-image underground canopy — the great majority of a tree's roots sit in the top 60 centimetres of soil and extend well beyond the branch spread.

**The actual shape.** Roots form a broad shallow plate rather than a deep taproot in most mature trees. Typical figures: **over 90% of roots in the top metre**, most within the top half metre, and lateral spread commonly **two to three times the canopy radius**, sometimes more in open ground. A deep taproot is common in seedlings of some species and is usually lost or reduced as the tree matures.

**Why shallow.** Roots need oxygen as well as water. Deep soil is frequently compacted, waterlogged or oxygen-poor, so roots concentrate where conditions suit them — near the surface, where rain, organic matter and air are.

**What follows practically:**

**The area to protect is wide.** Compacting, paving or changing levels anywhere within the root zone damages a tree, and the damage appears years later. Construction work is the commonest cause of urban tree decline, and the injury is usually done to roots nobody saw.

**Watering at the trunk is largely useless.** Absorbing roots are at the outer part of the spread, not the base.

**Root damage is not visible until the canopy responds**, which can take several seasons.

**On subsidence and drains.** Roots do not seek out and break intact pipes — that is a persistent myth. **They exploit existing defects**, entering cracked or poorly jointed drains where moisture escapes, then enlarging the problem. Subsidence risk is genuine on **shrinkable clay soils**, where a tree's water uptake shrinks the soil and can cause differential settlement; the risk depends on soil, species, distance and the building's foundations, not on trees generally.

**Before planting near a building**, consider mature size and species water demand rather than current size.

**Before removing a tree near a building on clay**, take advice — **heave** as the soil rehydrates can be as damaging as subsidence.

Question 2

How close to a house can you plant a tree?

Accepted Answer

It depends far more on soil type and species than on any single distance — and the mechanism people worry about is usually not the one that causes the damage. The misconception. Most people imagine

Question 3

What is a bare root plant, and when should you plant one?

Accepted Answer

A plant lifted from the ground during dormancy and sold without any soil around its roots — cheaper, frequently establishing better than a potted equivalent, and available only for a few months a

Question 4

How do plants actually drink, and why does a plant wilt?

Accepted Answer

Water is not pumped — it is pulled up the plant by evaporation from the leaves, and wilting is what happens when that pull outruns the supply. The mechanism, working from the top down: Transpiration.

Question 5

How does a seed know which way is up?

Accepted Answer

It detects gravity using falling starch grains inside specialised cells — a mechanism that works regardless of light, soil depth or which way up the seed happened to land, which is why planting

Question 6

What is a rootstock and why does it matter for fruit trees?

Accepted Answer

A rootstock is the root system a fruit tree is grafted onto. The scion — the variety you actually want, such as a Cox or a Bramley — is joined to it, and the rootstock determines much of how the tree

Question 7

How do plant diseases spread?

Accepted Answer

Through a small number of routes, and knowing which one a given disease uses tells you exactly which intervention will work — most garden disease advice fails because it addresses the wrong route.

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