← All guides · Annual maintenance · Updated September 2026

How to feed and mulch an established hedge in Broadstairs: the spring annual care routine for CT10 gardens.

Most established hedges in Broadstairs and St Peter's are cut once or twice a year and otherwise left entirely to their own devices. On deep, organically rich soils that often works. But on the thin Margate Chalk that underlies most of CT10, an established hedge without any supplementary care shows it over time: yellowing new growth, slow recovery after a hard cut, sections that thin at the base faster than they should. The spring feed and mulch takes under an hour for a typical garden run. Done right, it makes a visible difference to the hedge's vigour for the twelve months that follow.

Steps

Step 1: Wait for soil temperature, not the calendar date

The most common hedge feeding mistake is applying fertiliser too early. In CT10, the soil at 10cm depth reaches a reliable 10°C somewhere between late March and mid-April in most years. Granular fertiliser applied to cold soil does almost no useful work: the plant's root system is not yet actively growing, and a product sitting on cold, wet chalk can leach away through the fast-draining stone before the roots are in a position to take it up.

You do not need a soil thermometer. Push your finger 10cm into the soil at the hedge base. If it feels uncomfortably cold after five seconds, wait two weeks and test again. A reliable field indicator for CT10: if your privet or laurel hedge has started pushing out its first pale new tips, the soil is warm enough to feed. That usually means the last week of March or the first two weeks of April in most Broadstairs gardens.

Step 2: Check the hedge base for nesting birds, then clear debris

Before you disturb the base of any established hedge, walk the full length slowly and watch for adult birds entering or leaving the base section repeatedly. Dense, low established hedges, particularly privet, hawthorn and box, are a preferred nesting site for dunnock, blackbird and robin.

Once you have confirmed no active nests, pull any weeds from the base of the hedge, rake out old mulch if it has fully broken down into the soil (partially broken-down mulch can stay; it will continue to improve the soil structure below), and remove fallen leaves or compacted clippings from the previous season's cut. Packed clippings held against the stems through winter encourage fungal problems, particularly on box and laurel.

Step 3: Apply fertiliser at the correct rate for the species

For most established garden hedges in CT10, a granular balanced fertiliser applied once in spring is all that is needed. Growmore (7-7-7 NPK) is the standard UK choice: widely available, balanced nutrient profile, and slow enough in release not to force a sudden surge of soft growth that would require more frequent cutting. Apply at 35g per square metre along the root zone under the hedge. That is roughly a small handful per metre run for a hedge with a 1m-wide canopy, or two handfuls per metre for a hedge that is 1.5-2m wide. Scatter the granules evenly across the root zone and avoid concentrating them against the stems: granular fertiliser piled against a woody base can cause localised scorch on the bark.

The root zone extends roughly to the outer edge of the canopy drip line on each side. For a typical 1.5m-wide hedge, the feeding strip is 1.5-2m total width centred on the stems.

Yew, box and slow-growing formal hedges: use a fertiliser with a lower nitrogen (N) proportion relative to phosphorus (P) and potassium (K), or a slow-release granular product. High-nitrogen inputs on yew or box produce exactly the rapid, soft extension growth you are trying to avoid: it makes the hedge look untidy faster between cuts and is more vulnerable to frost and disease than hardened growth.

Evergreen coastal species (griselinia, escallonia, pittosporum, elaeagnus): balanced Growmore works well. These species support faster growth than formal box or yew without losing their structural value, so the standard balanced product is appropriate. A light second application in late May is acceptable if the growing season gets off to a strong start.

Organic alternative: blood, fish and bone applied at the packet rate in spring releases more slowly than a synthetic granular product and feeds gently through the season. Seaweed-based liquid feeds applied fortnightly from April to June can supplement either approach, and are particularly useful on the thinnest chalk soils in CT10 where trace element availability is sometimes limited.

Step 4: Water in the fertiliser if no rain is forecast within 48 hours

Granular fertiliser on dry chalk soil that sits without moisture for more than a week can concentrate on the surface rather than moving down into the root zone. If rain is forecast within 48 hours, leave the granules to be washed in naturally: a gentle soaking rain distributes the product more evenly than a hose. If the soil surface is dry and no rain is forecast, give the root zone a slow, thorough watering immediately after applying the granules. The aim is to wet the top 10-15cm of soil, not to saturate the surface and run off down the slope.

East Kent gets only around 615mm of rain a year at Manston, one of the drier parts of England. If you are feeding during a dry spell, do not assume rain will arrive quickly: water in manually.

Step 5: Apply bark mulch along the full hedge run

Bark mulch at the base of a hedge does three things: it suppresses weed growth that would compete with the hedge roots for water and nutrients; it reduces moisture loss from the chalk soil surface; and it breaks down slowly into organic matter that gradually improves the structure of the thin, low-organic chalk soil below. On Margate Chalk, where the topsoil above the rock is often 300mm deep or less, that slow accumulation of organic matter from the mulch is genuinely valuable over time.

Apply composted bark mulch at 75-100mm depth (3-4 inches). At less than 50mm, annual weeds push through easily. Use composted or part-composted bark, well-rotted compost or similar. Bark chippings and wood chip also work as a surface mulch, but keep them clear of the stems and do not dig them into the soil.

Keep a 50mm gap between the mulch and the hedge stems. Mulch piled directly against a woody stem holds moisture against the bark through winter and creates conditions for crown rot and collar rot, particularly on box, pittosporum and griselinia. Pull the mulch back slightly from the stem line: exact precision is not needed, a rough clearance of 50mm is enough.

The mulch strip should extend at least 400mm from the stem line on each accessible side of the hedge. Rake the mulch roughly level and do not compact it: mulch needs air gaps to function as an insulating and moisture-retaining layer.

Step 6: Decide whether a second feed in June is needed

Most established hedges in CT10 need only one fertiliser application per year, in spring. A second, lighter feed in June is useful in three situations: fast-growing hedges that are cut twice a year (privet, Leylandii, laurel); hedges in active recovery from a hard renovation cut the preceding winter; and hedges on particularly thin chalk where the spring application produced only a modest growth response.

A June top-up at half the spring rate (about 18g per square metre of Growmore, or one light application of blood, fish and bone) extends the benefit into the peak summer growing period without forcing soft growth vulnerable to autumn frosts. Do not apply a nitrogen-containing fertiliser after the end of July: late-season nitrogen produces soft growth that is at risk from early frosts. Potassium-rich fertiliser applied in late summer (such as sulphate of potash) is a legitimate option for hedges that have had a busy growing season: potassium helps harden growth before the cold without pushing new extension.

Why Margate Chalk changes the feeding calculation

The Upper Chalk formation underlying Broadstairs, St Peter's and the clifftop strips from North Foreland to Stone Bay is a porous, alkaline, free-draining rock that sits close to the surface across most of CT10. In many gardens the topsoil above the chalk is thin. In heavy rain, this chalk drains so fast that soluble nutrients applied to the surface leach downward through the thin topsoil layer before hedge roots can absorb them fully.

Two practical consequences follow. First, soluble fertilisers wash out faster than on heavier soils: granular slow-release products are preferable to liquid fast-release ones. Second, the organic matter content of chalk topsoil is naturally low, which means the soil holds less nutrient reserve between applications than clay or loam would. This is why established hedges in Broadstairs gardens often respond more visibly to a spring feed than the same species would in a garden on heavier soil: the chalk starts from a lower baseline, so the improvement from a feed is more marked.

Alkaline soils such as chalk can lock up trace elements including iron and manganese, producing yellowing growth (chlorosis) sometimes misdiagnosed as nitrogen deficiency. If the new growth on your hedge comes out pale yellow rather than the expected green, a trace-element feed is a better response than a larger dose of Growmore. This is relatively uncommon in established hedges but can occur on the thinnest chalk soils.

Three common mistakes

These are the commonest mistakes in hedge-base work:

• Mulch piled against the stems. This is the most consistent error and the one most likely to cause long-term damage. Bark mulch touching the stem line holds moisture against the bark through winter, creating conditions for crown rot and collar rot. It does not always kill the plant outright, but it weakens it steadily, and on stressed coastal hedges it can tip a vulnerable section into die-back over two or three winters. Keep the 50mm clearance from the stem.
• Mulch that is too thin. A layer under about 50mm lets annual weeds push through and dries out quickly on free-draining chalk. Aim for a good, even layer of 75-100mm, and top it up as it breaks down.
• Feeding a hedge that has just been cut back severely into old wood. A hedge that has been taken back hard in winter is under considerable stress. Applying a high-nitrogen fertiliser the following spring before the plant has stabilised pushes it to produce rapid, soft growth from the cut surfaces before the root system has rebuilt enough reserves to sustain it. After a hard renovation cut, wait until the first flush of recovery growth has appeared and hardened slightly, then feed at half rate: in CT10 conditions that means May rather than March.

Sources: Hopes Grove Nurseries, "Feeding a Leylandii Hedge" and "Looking After Your New Hedge" (hopesgrovenurseries.co.uk); Agrigem UK, "How To Fertilise a Hedge" (agrigem.co.uk/advice-centre/how-to-guides/trees-ornamentals/how-to-fertilise-a-hedge/); Hedging Plants Direct, "How to Fertilise a Hedge: Essential Tips for Healthy Growth" (hedgingplantsdirect.co.uk); MOOWY UK, "The Ultimate Guide to Fertilising Hedges" (moowy.co.uk); Royal Horticultural Society, "How to Grow Hedges" (rhs.org.uk/plants/types/hedges/growing-guide); British Geological Survey, Upper Chalk (Chalk Group) formation notes; Met Office climate averages 1991-2020, Manston station; Wildlife and Countryside Act 1981, section 1.