Filling a gap in your hedge in Deal and Walmer: four methods compared.
A bare section in an otherwise healthy hedge is one of the most common questions I get called out to look at in Deal and Walmer gardens. Before you reach for new plants, it is worth understanding what caused the gap: the answer usually determines which of the four main approaches will actually work, and which will fail again for the same reason.
Gaps appear for several reasons: salt wind killing a weak or exposed section of privet or griselinia on the seafront; drought stress on newly planted hedging in CT14's fast-draining shingle and alluvium ground during the first summer; disease (box blight in a formal box hedge, honey fungus in an old privet run); physical damage from vehicles reversing into a garden hedge; or simply age, with one section of a mixed native hedgerow failing while the rest remains strong. The cause matters because planting new stock into diseased soil, or into a spot that is still too dry, will produce a new gap in the same place within two seasons.
The four approaches below cover the realistic options for a Deal or Walmer garden hedge. They are not equally suited to all species or all gap sizes, which is what the comparison tables set out.
Before you start: safety notes for gap-filling and hedge work
- Eye protection. Cutting or training stems close to the interior of a hedge, especially hawthorn, holly or blackthorn, puts sharp material at face height. Wear safety glasses for any work in the hedge interior.
- Gloves. Holly, hawthorn, blackthorn and rose all carry thorns or spines capable of serious puncture wounds. Leather gloves, not light garden gloves, for work in these species.
- Wasp nests. Before putting a hand or tool into a gap in a hedge, tap the hedge base gently and watch for activity. Late summer and early autumn gaps often shelter active wasp nests. A stick tapped in first costs nothing; a disturbed nest costs considerably more.
- Ladder caution. Gap-filling in a tall hedge sometimes involves cutting higher stems to force lateral growth. Use a long-reach pole pruner from the ground rather than a ladder where height allows.
Four approaches to filling a gap: which suits your hedge?
The table below compares the four main options. "Time to fill" assumes a gap of 0.5–1m wide in an actively growing hedge; a larger gap or a slow-growing species adds time proportionally.
| Method | How it works | Best gap size | Time to fill | Difficulty | Typical cost (DIY) | Best for | Avoid when |
|---|---|---|---|---|---|---|---|
| 1. Hard-cut adjacent stems to force lateral growth | Cut the stems immediately either side of the gap back by a third to a half, stimulating dormant buds lower on the stem to push outward into the gap | Under 40cm wide | 1–2 growing seasons | Low | Nil (own tools only) | Privet, laurel, yew, hawthorn: species that break well from old wood | Leylandii or thuja (will not regenerate from old stems); gaps caused by disease (cutting spreads it) |
| 2. Plant new stock into the gap | Remove the dead material, prepare and improve the soil, plant one or two new specimens of the same species (bare-root in winter, pot-grown any time) and nurse them for the first season | Any size, but most cost-effective at 40cm–1.5m | 2–4 seasons | Low to medium | £5–30 per plant (bare-root cheaper; pot-grown faster but pricier) | Any species where adjacent stems are too old or too far away to train into the gap | Diseased soil without treatment first; drought-exposed positions without improved watering; gaps caused by vehicle compaction without soil remediation |
| 3. Peg and train adjacent stems into the gap (simplified pleaching) | Bend living stems from either side of the gap toward the centre, peg or tie them in place to a temporary cane framework, and let them root if conditions allow or simply grow across to close the gap from above | 30cm–80cm | 1–3 seasons | Medium | Nil to £10 (canes and soft ties) | Hawthorn, blackthorn, field maple, privet: flexible-stemmed species with enough length to reach across | Stiff-stemmed species (holly, mature laurel, yew) where forcing a bend risks snapping the stem; gaps wider than the reach of available adjacent material |
| 4. Remove and replant the whole section | Grub out the entire failing section (stump and roots), treat or replace the soil if disease is present, replant with new stock at full hedge spacing, and nurse from scratch | Any size; the only realistic option above 1.5m of continuous failure | 3–6 seasons | Medium to high | £20–150+ depending on section length and species choice | Disease-caused gaps (honey fungus, box blight); gaps where the root system is rotting; old leylandii sections where adjacent growth cannot close the bare zone | Rarely avoided for disease-caused failure: this is the correct approach when the underlying cause has not been resolved |
Nesting season: do not work inside a hedge between 1 March and 31 August without a survey walk first
UK Wildlife and Countryside Act 1981, section 1 makes it an offence to intentionally take, damage or destroy an active wild bird's nest. Nesting season runs 1 March to 31 August. The maximum penalty is a £5,000 fine per nest and up to six months in prison.
Gap-filling work, particularly Method 3 (training stems into the gap), involves reaching into the hedge interior: exactly where nests are built. Before any work between March and August, walk the hedge line slowly, look into the interior at multiple heights, and tap the base gently. On the Kingsdown cliff hedges near the SSSI corridor, and on the dense privet and laurel hedges behind the Deal seafront, nesting density can be high in a good season.
The safest window for any gap-filling work involving cutting or training existing stems is September to end of February. New planting into a prepared gap can go in at any time but October to March is the preferred window for bare-root stock. See the nesting-season guide for the Kingsdown-specific survey-walk protocol.
Species comparison: which gap-filling methods work on CT14 coast species?
Not every method works for every species. The table below cross-references the seven species I see most in Deal, Walmer and Kingsdown gardens against the four methods above, with notes on the coastal growing conditions that affect the outcome.
| Species | Method 1: hard-cut adjacent stems | Method 2: plant new stock | Method 3: peg and train adjacent stems | Method 4: replant whole section | CT14 coastal notes |
|---|---|---|---|---|---|
| Privet (Ligustrum spp.) | Excellent: breaks from old wood readily, lateral growth fills a small gap within one season | Good: bare-root privet is cheap (around £3–5 per plant) and establishes quickly on CT14 alluvium | Good: privet stems are flexible enough to train when young; use in winter | Use only if disease or severe root failure is confirmed | The most forgiving gap-filling species on the CT14 coast. A healthy privet hedge either side of a gap will often close it from Method 1 alone in a single growing season. Gap caused by drought in the first year after planting: improve the soil and replant, do not try to train old stems across. |
| Cherry laurel (Prunus laurocerasus) | Good: responds well to hard cuts and pushes strong regrowth from old wood, particularly in July–August | Good: pot-grown laurel establishes well if watered through the first summer on CT14's fast-draining ground | Poor: stems are stiff once mature; forcing a bend usually snaps them | Correct approach if honey fungus is the cause (phytosanitary treatment of soil first) | Large-leaved laurel gaps in Deal terraced gardens are often caused by shade: a section under a newly grown tree canopy stops getting light. In that case, Method 1 is unlikely to work either, because the new lateral growth will have the same light problem. Method 2 or 4 with a shade-tolerant species substituted is the practical answer. |
| Griselinia (Griselinia littoralis) | Moderate: griselinia breaks from old wood more slowly than privet or laurel; give it a full season before judging progress | Good: pot-grown griselinia is the standard replacement on Walmer seafront plots; plant in spring or early summer for best establishment on salt-exposed ground | Moderate: young griselinia stems can be trained but old, thick stems are not flexible; this method works best on hedges under five years old | Needed if the gap is caused by winter salt-wind kill of a weakened section: improve the windward side's protection and replant with pot-grown stock | Griselinia gaps on the CT14 seafront are usually caused by one of two things: a hard winter killing a section that was already stressed by summer drought, or a section that was planted without adequate wind-shelter in the establishment period. On the Walmer seafront between The Strand and St Clare Road, I see this regularly. The fix is Method 2 with pot-grown stock in spring, with a temporary windbreak (hessian on posts) through the first winter. |
| Escallonia (Escallonia spp.) | Good: escallonia regrows from hard cuts well and produces lateral shoots from old wood within one season; cut the adjacent stems in late August after flowering | Good: pot-grown escallonia establishes well. Avoid autumn planting on exposed seafront plots; spring planting (April–May) works better at Kingsdown and the Walmer shore | Good: young escallonia stems are pliable enough to train in late winter; particularly effective in the hedgerow restoration approach used for country boundaries at Sholden and upper Kingsdown | Use if the section has failed from the base upward over several years: occasionally a mature escallonia section will simply exhaust itself, particularly where the soil is very free-draining shingle | Escallonia on the Kingsdown cliff gardens is one of the most reliable boundary hedges in the whole area, but gaps do appear after severe gales if one section catches more wind than its neighbours. Method 1 or 3 will usually close a gale-opened gap within two seasons. Do not clip the replacement growth for the first full season after training: let it knit before you trim it back. |
| Hawthorn (Crataegus monogyna) | Excellent: hawthorn breaks vigorously from old wood and will throw lateral shoots into a gap very quickly in the season after a hard cut | Good: bare-root whips are cheap at £1–3 each, plant October to March; use two or three whips per 60cm of gap length for faster closure | Excellent: hawthorn's flexibility when young and long-shoot growth pattern make it the easiest species to peg and train; this is the traditional hedge-gap repair approach for a rural Sholden or Kingsdown boundary hedge | Rarely needed unless the section is dead down to the root crown; hawthorn usually produces basal regrowth from the stump even after apparent above-ground death | Hawthorn is the most gap-filling-friendly species by a clear margin. Moor Meadows, working with the Devon Hedge Group, published a detailed video on using hedge-laying technique to fill hawthorn and mixed-species hedgerow gaps (Part 3 in their hedgerow management series, on their YouTube channel). The principle of pegging active stems across a gap applies equally in a Sholden field boundary context and in a smaller Deal or Kingsdown garden boundary. The one CT14-specific note: hawthorn in the hedgerows behind the Kingsdown-to-Deal shore is often heavily used for nesting; the September–February window is essential for any training or cutting work on these plants. |
| Leylandii (x Cuprocyparis leylandii) | Poor to useless: adjacent leylandii stems will not regenerate from old brown wood, so forcing lateral growth into a gap rarely produces anything green | Possible but slow: a new leylandii plant in the gap will take four to seven years to match the height of an established hedge | Poor: leylandii stems are too stiff and too likely to have already gone brown inside to peg successfully | Often the correct answer for a leylandii gap: consider whether to replace with thuja plicata 'Brabant', which handles CT14 coastal alluvium better and can be renovated from old wood if the hedge grows too large again | Leylandii gaps are often permanent in the sense that no technique will restore the existing hedge quickly. For a short gap (under 30cm) next to young green growth, Method 2 with a new specimen is the most realistic option. For anything larger, I usually recommend a frank conversation about whether leylandii is the right long-term species for the plot. The conifer hedge guide covers thuja plicata 'Brabant' as the replacement option for CT14 coastal gardens. |
| Mixed native hedgerow (hawthorn, blackthorn, field maple, hazel) | Good: at least one species in a mixed hedge will usually break from old wood on either side of a gap; cut back the adjacent stems of the most responsive species | Excellent: use the same species mix used in the original hedge; bare-root whips are cheap and can be planted densely (2–3 per 50cm) for faster closure | Excellent: mixed native hedges are the classic application for training-into-a-gap; hawthorn and blackthorn in particular respond well and produce dense, stock-proof closure within two to three seasons | Use if the failure extends more than 1.5m and the adjacent stems are not close enough or vigorous enough to train across | Mixed native hedgerow gaps at Sholden, Upper Deal and along the approach lanes toward Ripple and Kingsdown are common after gale-season damage or where a tractor or vehicle has run into the hedge base. The nurse-planting approach (Method 2) at high density gives the fastest results and the most wildlife value once the new plants establish. Use the CT14 seafront-adjusted species proportions from the mixed native hedgerow guide for replanting: 50 per cent hawthorn, 25 per cent blackthorn, with field maple, hazel and dog rose to fill. |
Diagnosing the cause before you start.
The single most useful thing I do before recommending a gap-filling approach is spend five minutes working out why the gap is there. The diagnosis changes the method significantly.
A section of privet or griselinia with dead stems that break cleanly and dry brown at the cut surface is almost always drought or frost kill: the roots are still alive and the stump will push new growth in the following season. Method 1 (hard-cutting the adjacent live stems) combined with watching what the dead stump itself produces is usually the right first step. Do not grub out a dead-looking privet stump until you have waited one full season to see whether it pushes basal shoots: it usually does.
A section with slimy, black or dark brown stems at the base, particularly if the leaves were yellowing and falling before the section died, points toward honey fungus (Armillaria species). You will often find dark brown bootlace-like rhizomorphs in the soil around the dead root crown. In that case, Methods 1, 2 and 3 applied to the same spot will all fail within one to two seasons unless you remove the infected root material and treat the soil. Method 4 is the correct approach, and even then, replacing with a honey-fungus-tolerant species (privet is reasonably tolerant; box and cherry laurel are susceptible) reduces the risk of a repeat. The hedge diseases guide covers honey fungus identification in detail.
A gap on a Walmer or Kingsdown seafront plot that appears after a hard winter, particularly one with prolonged easterly winds, is most likely salt or cold wind kill of a section that was already weaker than its neighbours: perhaps younger plants, or a section planted in a slight hollow that pooled cold air. Removing and replanting with the same species in the same spot without addressing the exposure is likely to produce the same result. A temporary hessian windbreak on posts, left in place through the first two winters, makes a significant difference to the survival of replacement griselinia or escallonia on an exposed CT14 plot.
Hawthorn and hedge-laying: the traditional approach to gap repair.
For rural hedgerow gaps in a country boundary context, the oldest and most effective technique is a simplified form of hedge laying: bending living stems from either side of the gap toward the centre and holding them in place with stakes or pegs so they grow across and knit together. This is the basis of Method 3 in the table above.
Moor Meadows, a Dartmoor-based conservation group working with the Devon Hedge Group, published a practical video series on their YouTube channel covering exactly this approach. The third video in the series, "Part 3: Curing a gap", demonstrates the technique with expert Tom Hynes on a mixed-species Devon boundary hedge. The principles transfer directly to a hawthorn, blackthorn or mixed native hedgerow gap at Sholden, Upper Kingsdown or one of the farm boundary hedges between Deal and Ripple, though the style of work differs from a full Devon hedge (which has a stone or earth bank beneath it that most Kent hedges do not). The Hedgelink partnership, which supports the series, provides the video as a free resource at hedgelink.org.uk. For garden hedges in Deal or Walmer, Method 3 works best where the adjacent stems are under about five years old and still flexible: stiffer mature stems from laurel or older privet are not good candidates for bending.
Planting into a gap: the ground matters as much as the plant.
One reason new plants fail in the same gap a second time is that nobody improved the ground before replanting. On CT14's coastal alluvium and shingle, the soil in an established hedge run has often been depleted by years of root competition from the existing hedge, and may also be compacted or contaminated if the gap was caused by physical damage. Before planting into a gap, I always do these four things: dig out the dead root material; break up any compacted subsoil with a fork; work in a bucketful of garden compost or well-rotted manure per square metre; and check the drainage (if water sits in the hole for more than thirty minutes after heavy rain, the replanted stock will need a raised planting position or a gravel sump beneath it).
Bare-root stock is cheaper and often establishes better than pot-grown in an open hedge position, but only for planting between October and March. If the gap needs filling at another time of year, pot-grown stock is the right choice: it is more expensive but can go in from April to September if watered regularly through the establishment period. On a CT14 coastal alluvium plot in its first summer, that means a serious watering commitment: every two to three days in a dry spell for griselinia, privet or laurel. The first summer failure rate on coastal plots drops dramatically with good watering. The new hedge aftercare guide covers watering schedules and mulch depths in detail for the species most commonly used to fill gaps on this coast.
Conservation areas: is a planning notice needed to fill a gap?
In Deal's seven conservation areas, removing dead material from a hedge gap and replanting with new hedging stock is exempt from the section-211 notice requirement. The notice applies to individual trees over 75mm stem diameter at 1.5m height, not to hedging species doing their boundary job.
The question occasionally arises when the gap has been caused by the death of a large individual specimen that had grown above hedge height and above the 75mm threshold: a large holly or yew standard that has died. Removing the stump of such a specimen in a conservation area is worth checking first. In practice, Dover District Council's arboricultural officer is usually pragmatic about dead specimen removal in a hedge context, but a brief call before you start costs nothing and avoids the possibility of an enforcement notice. The full detail is in the conservation-area rules guide.
Gap in your hedge in Deal, Walmer or Kingsdown? Get a diagnosis before you replant.
Call or WhatsApp me on 07763 100 477, or email hello@dealhedges.co.uk. I can tell you what caused the gap, which of the four methods will work for your species and position, and whether the soil needs preparing before you plant. I cover Deal, Walmer, Kingsdown, Mill Hill, Sholden and the CT14 shore. Contact me.
Sources: Moor Meadows / Devon Hedge Group, "Part 3: Curing a gap" (YouTube, via hedgelink.org.uk); Royal Horticultural Society, "Hedges: renovation techniques" (rhs.org.uk); Hedgelink, "Life on the Hedge: Close the Gap" project resources (hedgelink.org.uk); UK Wildlife and Countryside Act 1981 section 1 (nesting season); Town and Country Planning Act 1990 section 211 (conservation area notice requirements); contractor experience on CT14 coastal alluvium and shingle ground, 2019–2026.