Hedge shape myths: three mistakes that strip Thanet hedges bare.
Every few weeks on a job in Cliftonville or Westgate-on-Sea, I see the same thing: a hedge that has lost its base. Green at the top, brown and bare from knee height down. The owner either blames a disease or the salt wind. Sometimes those are factors. More often, it is the shape they have been cutting it. Three shape myths cause more base die-back in Thanet gardens CT8 to CT12 than anything else I see.
Myth 1: “Cutting the sides vertically looks neat and does not affect the health of the hedge.”
Myth: vertical sides are tidy and harmless. Fact: they shade out the base.
When you cut a hedge with sides that go straight up and down, the widest point of the hedge is at the top. The canopy overhangs the lower sections. Within a growing season, the bottom third of the hedge starts receiving less direct light than it needs to stay in growth. The shading is not dramatic, but it is consistent, every day, across the whole growing season.
Some species tolerate this for years because they are genuinely shade-tolerant. Yew (Taxus baccata) is a woodland understorey plant that evolved in low-light conditions. Beech and hornbeam are similarly shade-tolerant. You can cut these with vertical sides for a decade before the base starts to fail, and even then a hard renovation may fix it.
The species that dominate Thanet’s salt-belt front gardens from Westgate CT8 through Margate CT9, Cliftonville and Broadstairs CT10 to Ramsgate CT11/CT12 are different. Escallonia, griselinia littoralis and tamarix are all light-demanding species. They do not slow down gradually in low light: they die back. The base goes brown. Once it is gone, there is nothing to regenerate from, because these species do not shoot from old bare wood. That failure is permanent on the section.
The correct profile is what horticulturists call the “batter”: a slight inward taper from the base upwards, so the widest point is at ground level and the top is narrower. The RHS describes this as cutting the hedge so it is “slightly wider at the bottom than the top” to ensure “light can reach the lower part of the hedge.” It does not require an exaggerated slope. On a 1.5 metre hedge, the top being 10–15 cm narrower on each side than the base is enough. The difference is invisible at a glance but matters to the plant.
Myth 2: “Once the base has gone bare, cutting it back harder will bring it back.”
Myth: hard renovation fixes a bare base. Fact: on Thanet’s coastal species, it makes it permanent.
This is the follow-on mistake. The base is bare, so the owner concludes the hedge needs a hard cut to force new growth from the base. On the right species, that logic is correct. Beech and hornbeam respond well to hard renovation: cut them back to the main framework in winter and they push new growth from every cut point. Yew is the textbook example of a plant that regenerates from old bare wood: cut it back hard to a stump and it will reshoot.
The coastal salt-belt species are the opposite:
- Escallonia: cannot regenerate from old bare stems. There are no dormant buds in the woody structure. This is the same reason leylandii cannot be cut back hard on Thanet chalk (covered separately on this site). Cut past the live canopy on an escallonia and that stem stays bare. If the whole base has gone, hard cutting accelerates the decline rather than reversing it.
- Griselinia littoralis: more tolerant than escallonia, but on the shallow chalk geology in Margate CT9 and Cliftonville (Margate Chalk Formation topsoil depth is typically 15–35 cm over parent chalk in town-centre gardens), cutting back hard frequently stresses the plant enough to kill the section outright rather than prompt regeneration.
- Tamarix: a genuine exception, but a specific one. Tamarix tolerates and benefits from hard cut-back, but only at the right time: immediately after flowering (late spring for T. ramosissima, which flowers June/July on the Thanet coast). Hard cut-back at the wrong season compounds the problem.
If the base of a coastal hedge has already died back, the practical path is: reshape what remains to the correct batter profile going forward; replant the dead sections in autumn (October to February, the correct planting window on Thanet chalk); accept that on escallonia and griselinia, the dead base will not green back up.
| Species | Regenerates from old bare wood? | Hard renovation useful? |
|---|---|---|
| Yew (Taxus baccata) | Yes, reliably | Yes, any time of year in winter |
| Beech / hornbeam | Yes, from framework | Yes, winter renovation works |
| Tamarix | Yes, but timing-dependent | Yes, immediately after flowering only |
| Griselinia littoralis | Partially, on strong plants | Risky on Thanet chalk; replanting is safer |
| Escallonia | No | No: accelerates decline |
Myth 3: “The batter shape only matters for formal clipped hedges. Coastal escallonia does not need it.”
Myth: informal coastal hedges are forgiving about profile. Fact: they are less forgiving, not more.
There is a certain logic to this. If you are cutting a box or yew hedge into a formal geometric shape, the batter matters for the geometry: straight sides bulge at the top, the top casts shade, the whole thing looks wrong as well as becoming progressively barer at the base. But an informal coastal escallonia does not have a precise shape to maintain, so the argument goes: does it really matter if the sides are not perfectly angled?
It matters more, not less. Coastal salt-belt species on Thanet’s chalk are fighting two problems simultaneously in a way that inland species are not.
The first is salt-wind desiccation. On the seaward face of hedges along the Thanet coast, particularly at Cliftonville, Westgate-on-Sea CT8 and Birchington CT7 where the chalk coast is most exposed, autumn and winter gales drive salt spray directly into the outer canopy. The outer face of the hedge already takes a battering (the brown-off and partial defoliation you see on the exposed face of most coastal hedges here after a February gale). The base of a coastal hedge is therefore fighting desiccation from the wind and shade from the canopy above at the same time. Getting the profile right removes one of those two stressors. Keeping the vertical profile means the base fights both at once.
The second is root restriction. Thanet’s Margate Chalk Formation runs close to the surface across much of CT9 Margate, Cliftonville and CT10 Broadstairs. Topsoil depth in front gardens on the chalk ridge is often 15–35 cm before hitting the parent material. A shallow-rooted escallonia or griselinia on Thanet chalk does not carry the stored energy reserves that a deep-rooted inland specimen would. There is no fat cushion in the root system to push replacement growth from the base if shading causes the lower canopy to fail. What the plant has is what you can see: keep it healthy, keep it green to the ground, and get the profile right from the start.
Nesting season and corrective cutting
If you are reshaping a hedge to correct a vertical-sided profile, you are trimming the hedge: the Wildlife and Countryside Act 1981, section 1 applies. The nesting season runs 1 March to 31 August; cutting inside that window requires a visual nest check first (walk both sides slowly, look for adult birds returning repeatedly to the same point, listen for alarm calls). The safe default cutting window for corrective work and for establishing the batter profile is September to late February. Penalty on conviction: up to £5,000 per offence. See: Nesting, hedgehogs & Thanet’s wildlife law and the hedge-cutting timing guide.
What the correct batter looks like in practice
These are the numbers I work to on a standard domestic Thanet garden hedge:
- Up to 1 m tall: vertical sides are fine. The top does not cast meaningful shade onto the lower sections at this height. No batter needed.
- 1–1.5 m tall: a slight taper: roughly 5–8 cm narrower at the top than at the base on each side. Small, but effective.
- 1.5–2 m tall: the batter matters. Aim for the top to be 10–15 cm narrower on each side than the base. You can eyeball this: stand back and check that the base is visibly wider than the top.
- Over 2 m tall: the batter becomes critical. A 2.5 m hedge with vertical sides is shading its own base significantly. Top should be noticeably narrower: 15–20 cm per side is not excessive.
A practical method: when you are finishing the side faces, tilt the trimmer blade slightly inward at the top, outward at the base. You do not need a guide string, though one helps if you are doing a long run in a formal garden. The key check is at the end: stand back from the hedge and look. If the top profile is wider than or equal to the base, you have cut it wrong.
The video worth watching
The Royal Horticultural Society published a short film titled “What is the best way to cut a hedge?” in September 2025, presented by RHS Horticulturist Alesandra Sana. It covers the batter principle clearly, alongside the correct tool hold and the direction of cut (bottom up on the side faces). The RHS is the most authoritative UK gardening body and this is as clear a mainstream instruction as exists on the subject. Watch it at youtube.com/watch?v=HaiwL5SVc28.
Garden Ninja (Lee Burkhill, BBC One’s Garden Rescue, over 100,000 YouTube subscribers) covers the same principle in his hedge-trimming guide, with the specific observation that without the batter “the bottom of the hedge will end up receiving less light and then struggle, resulting in lots of lush growth on top and a weak hedge at the bottom.” That is exactly what I see on Thanet front gardens with vertically cut escallonia. His channel is at youtube.com/@Gardenninja.
Not sure if your hedge profile is causing the problem?
Send a photo of the hedge side-on (so I can see the profile) to hello@thanethedges.co.uk, or call / WhatsApp 07763 100 477. I can tell you whether the base die-back is a shape problem, a species problem or something else, and what a realistic fix looks like. No charge for that conversation.
Sources: RHS, “How to Trim a Hedge” and “Pruning Hedges: Expert Tips” (rhs.org.uk); RHS YouTube, “What is the best way to cut a hedge?” presented by Alesandra Sana, September 2025 (youtube.com/watch?v=HaiwL5SVc28); Garden Ninja (Lee Burkhill), “How to cut, prune & trim hedges: the ultimate beginner guide” (gardenninja.co.uk); BGS 1:50,000 geological series sheet 274 (Margate Chalk Formation distribution); RHS, “Hedges: Renovation Techniques” (rhs.org.uk/plants/types/hedges/renovation); Wildlife and Countryside Act 1981, section 1.