Hedge Plant Calculator: How Many Plants Do You Need?

How the calculation works

Working out how many plants a hedge needs

Planting a hedge looks simple, but the exact number of plants matters more than it first appears. Buying too few means a second order to the nursery, and the later plants may come from a different batch or be a different size, which shows in the finished hedge. Buying too many wastes money on plants that are left over. A correct count before you visit a garden centre or order online avoids both problems.

How the calculation works

The calculation starts from two values: the length of the hedge in metres and the spacing between plants in centimetres. The spacing is converted to metres, the length is divided by it, and the result is rounded up to the next whole number. Rounding up is not optional, because one plant short leaves an unfinished gap at the end of the run.

For a 10 metre hedge of photinia at 75 cm spacing, the sum is 10 ÷ 0.75 = 13.3, which rounds up to 14 plants. For a double row, the count is multiplied by two: 14 × 2 = 28 plants. The calculator assumes both rows use the same spacing as a single row, so the double-row figure is the single-row count repeated. It gives the number of plants to buy, not a detailed planting plan.

Single and double rows

A single row has one line of plants. A double row has two parallel lines, with the plants of the back row set into the gaps of the front row. Offsetting the rows by half a spacing fills those gaps and gives a denser and more opaque screen than one row of the same plants. A double row is worth considering when privacy from neighbours or road noise is the main aim, or when a hedge needs to screen a view quickly. The two rows are typically planted about 50 to 60 cm apart.

Choosing a species

The spacing ranges below are typical starting points, but each species behaves differently, and the choice affects how much trimming the hedge will need over its life.

Box (Buxus sempervirens) grows slowly and forms a very dense hedge. It suits low, formal hedges and tolerates clipping well. It is planted 30 to 40 cm apart. Box has been affected by box blight and box tree caterpillar in parts of the UK, so check current local advice before planting.

Photinia (Photinia × fraseri) is widely sold at garden centres and nurseries. Its new leaves are red, and it grows at a moderate pace. The usual spacing is 60 to 80 cm.

Cherry laurel (Prunus laurocerasus) is a robust shrub with large, glossy leaves. It suits taller hedges that need little maintenance, and it tolerates partial shade, which makes it useful beside trees. Spacing is typically 80 to 100 cm. All parts of the plant are poisonous.

Laurustinus (Viburnum tinus) is a Mediterranean shrub that flowers white in winter and carries blue-black berries in autumn. It suits informal hedges and gardens that aim to support wildlife. Spacing is 80 to 100 cm.

Leylandii (× Cupressocyparis leylandii) is the fastest-growing species in this list and is often chosen when privacy is needed quickly. The usual spacing is 60 cm, which can be reduced to 40 cm for a denser hedge in less time. Its rapid growth means it needs regular trimming and can become tall quickly, so consider its eventual height before planting.

Yew (Taxus baccata) grows slowly but lives for a very long time. It tolerates clipping, shade and chalky soils. Formal hedges are planted 40 to 50 cm apart. All parts of the plant except the red aril are poisonous.

Privet (Ligustrum ovalifolium) grows quickly, is widely used for boundary hedges, and copes with hard pruning. Spacing is 60 to 80 cm.

Measuring the hedge correctly

The most frequent error is measuring the length badly. Few hedges run in a perfectly straight line. Walls, gates and corners interrupt them, so each straight run should be measured separately. Each separate run also needs its own end plants, so the total from several short runs can be slightly higher than a single rounded figure for the same overall length. Run the calculator once for each run if you want the most accurate quantity.

Choosing plant size

The second common mistake is buying small plants because they cost less and are expected to catch up. Hedges take several years to reach a useful height and density, even with fast-growing species. Larger plants cost more per plant but give a more established look sooner. Nursery stock is graded to the specification in BS 3936, so compare sizes and grades when getting quotes.

Keeping the spacing

The third mistake is ignoring the spacing given for the species. Planting closer together increases competition for water and nutrients. Over time this can leave a hedge thin at the base or unhealthy in the middle, which is hard to correct once the plants have grown. Keep to the recommended spacing, or accept the extra plants that a closer spacing requires.

Planting season and aftercare

Bare-root hedging is lifted and sold while dormant, so it is normally planted from late autumn to early spring, when the ground is neither frozen nor waterlogged. Container-grown plants can go in at most times of year, but they need regular watering through their first summer. A mulch around the base helps retain moisture, and new plants should not be left to dry out during hot spells.

Legal and boundary points

Check the rules before planting along a shared boundary. Local planning rules, conservation area restrictions, deeds, covenants and estate management rules may all apply, and they vary from one property to another, so check with your local council and the title plan before you plant. A dispute over a hedge is much harder to resolve once it is established.

Evergreen hedges over 2 metres high that adversely affect the reasonable enjoyment of a neighbouring home can be the subject of a complaint under the high hedges provisions of the Anti-social Behaviour Act 2003 in England and Wales, or under the High Hedges (Scotland) Act 2013 in Scotland.

When not to rely on the calculator

The calculator sorts out quantities only. It does not check whether a species suits the soil, the light or the local climate. For a simple domestic hedge of up to about 50 metres, the calculator and the species information are usually enough. For difficult ground, such as heavy clay, waterlogged soil, or soil that is very acid or alkaline, a landscape professional is worth consulting. The same applies to large rural runs and to hedges where the boundary line is unclear.