Tree planting conditions: species, stock size and establishment

A tree planting condition usually asks for three things: an approved planting plan and schedule, planting within a stated season, and replacement of anything that dies within a defined establishment period, commonly five years. Discharging it is easy. Passing the end of the establishment period with the trees alive is the part that gets neglected, and replacement obligations have a habit of surfacing when a site is being sold.

The technical choices that decide survival are made at specification stage, not at planting.

What the condition usually requires

Read the wording carefully, because the standard forms differ in ways that matter.

Most conditions require a scheme to be submitted and approved before a stated trigger, planting to be carried out in the first planting season following completion or occupation, and any tree that dies, is removed, or becomes seriously damaged or diseased within the establishment period to be replaced in the next planting season with a tree of similar size and species.

Three details are worth checking. Whether the establishment period runs from planting or from completion of the development. Whether replacement is required once or repeatedly. And whether the condition also requires a maintenance schedule, because without one the obligation to keep trees alive has no specification attached to it.

Choosing species for the location

Species selection is the decision with the longest consequences and it is routinely made from a habit list.

Match the species to the soil, the exposure, the available rooting volume and the ultimate size the position can accommodate. A tree that will outgrow its space is removed within twenty years, which defeats the point. Consider the local character too, because a planting scheme in a conservation area or a National Landscape that ignores the prevailing species will be resisted.

Diversity is the other principle worth applying. Spreading a scheme across several species, genera and families limits the damage a single pest or pathogen can do, and recent experience with ash and with oak pests makes the case better than any argument.

Then think about biosecurity. Ask where the stock was grown, not simply where it was bought. Stock grown in the country of planting, with a traceable nursery history, reduces the risk of importing a pest with the rootball. Some authorities now write sourcing requirements into landscape conditions.

Stock size and why bigger is not better

Clients want instant effect, and specifiers give them heavy standards because they look finished on handover day.

The arboricultural reality is that larger nursery stock carries proportionally less root, takes longer to establish, needs more water for longer, and fails more often. Whips and transplants establish quickly, grow away faster, and frequently overtake heavy standards within the first decade. They also cost a fraction as much, which means more of them and more diversity for the same budget.

Where a large tree is needed for a specific reason, in a formal street or a civic space, specify it deliberately and fund the irrigation and aftercare that goes with it. Where it is not, resist it. A planting schedule mixing a small number of standards at focal points with whips and feathered stock elsewhere will look better in year ten than one made entirely of heavy standards.

Specify stock properly using the recognised nursery stock categories, with girth or height, root type, and form, so that what arrives is what was designed.

Soil volume and the rooting environment

Soil volume sets the size a tree can reach. Everything else is secondary.

In a landscape setting with open ground the volume looks after itself. In a car park, a courtyard or a street, it does not, and a tree in a one metre cube of topsoil surrounded by compacted sub-base will stall at a fraction of its potential size and then decline.

The engineering answers are established: continuous rooting trenches linking pits, load-bearing cell systems that allow soil to remain uncompacted beneath paving, structural soils, and irrigation and aeration provision built into the pit. All of them need to be on a drawing before the levels and the drainage are fixed, because retrofitting rooting volume into a completed hard surface is not practical.

Where a tree pit sits near drainage runs or service corridors, the conflict has to be resolved on paper first. The same coordination problem arises with existing trees on a site, which our note on retaining a tree through a construction programme deals with in detail.

Establishment maintenance

The establishment period is where the money is spent and where schemes fail.

• Watering through the first two or three growing seasons, at volumes and intervals stated in the schedule rather than left to judgement
• A weed-free and grass-free circle around the stem, maintained, because grass competition kills more young trees than drought
• Mulch renewed rather than applied once and forgotten
• Stakes and ties checked, adjusted and removed on time, since a tie left on will girdle the stem
• Formative pruning in the early years, which costs little and prevents expensive remedial work later
• Protection from strimmers, mowers and livestock, which is the most common cause of avoidable loss

Put all of this in the maintenance schedule submitted with the scheme, with responsibilities named. A schedule that says trees will be maintained in accordance with good horticultural practice discharges nothing.

Failure and replacement

Expect some losses. A scheme with no failures over five years is unusual, and a condition written as though failure is misconduct produces arguments rather than trees.

The workable approach is to monitor annually, record condition with dated photographs, replace in the following dormant season, and investigate the cause where losses cluster. Clustered failures usually indicate a soil or drainage problem rather than bad luck, and replanting into the same conditions produces the same result.

Where the planting also delivers biodiversity units or mitigates an arboricultural loss, replacement is not optional and the monitoring obligation is likely to run for much longer under a separate agreement.

One further point. Where the planting scheme replaces trees lost to the development, the replacement ratio and the species should relate to what was removed, and the tree survey that recorded the existing trees is the document the authority will check the scheme against.

Evidence for final sign-off

Assemble it as you go rather than at the end.

An as-built planting plan showing what was planted where. Delivery notes and invoices identifying species, stock size and nursery. Dated photographs at planting and at each annual inspection. The watering and maintenance records. And, at the end of the period, a short condition report from an arboriculturist confirming survival and health.

That package closes the condition in one submission. Its absence turns a formality into a site visit, a request for information and a delay at exactly the point a site is being handed over. The specification discipline is the same one that applies to pruning work, which we cover in writing pruning specifications properly, and it belongs in the Landscape Strategy submitted with the application.

This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it.

PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.