← All guides · Aftercare · Updated September 2026

Hedge pests and diseases in Medway. A month-by-month management calendar.

Box tree moth is now widespread across south-east England, so a box hedge in the Medway towns should be checked for it every season. Box blight, aphids and scale insects add to the picture. The good news is that almost all of it is manageable if you act at the right point in the calendar rather than waiting until the damage is obvious. Here is when to look and what to do, month by month across ME1 to ME8.

This calendar concentrates on the pests and diseases most likely to affect hedges in the Medway towns - principally on box, which is common in formal front gardens across Chatham, Rochester and Gillingham. It also covers the aphid and scale-insect problems that affect hawthorn, privet, viburnum and laurel across the patch. Chartered horticulturist and UK TV gardener David Domoney covered the core box hedge care and problem identification well in a 2024 YouTube guide; the calendar structure here maps that knowledge onto the Medway growing season and ties it to the nesting-season constraints any ME1-ME8 garden has to observe.

1. January - February: the dormancy survey

   No caterpillar pests are active in deep winter, but this is the best time to do a close inspection precisely because the foliage is thinner and the stems are bare on deciduous species. On box, look at the stem bark for the pale, waxy encrustation of scale insects, such as euonymus scale. These are sap-suckers that weaken the plant slowly; a light infestation on a healthy box is not an emergency, but a heavy covering on stressed or shaded plants is worth recording so you can treat in spring before the crawlers emerge.

   Check the soil around the base of any hedge that has shown unexplained die-back in previous seasons. Honey fungus (Armillaria species) produces dark, bootlace-like rhizomorphs under the bark and in the soil. If you find them around an old stump where a hedge section was removed, that stump needs to come out completely, including roots where possible. The fungus will move to adjacent live material along soil contact. It is most often found in older gardens where dead stumps have been left in the ground for years.

2. March - April: nesting season opens, first moths and aphids appear

   Under the Wildlife and Countryside Act 1981, section 1, damaging or destroying a wild bird's nest while it is in use or being built is a criminal offence, punishable on conviction by a fine, up to six months in prison, or both, counted per nest. The Act sets no calendar dates; 1 March to 31 August is the period RSPB and GOV.UK guidance advises avoiding hedge cutting. This is relevant to pest management because the instinct when you spot caterpillar damage in spring is to strip out the affected sections immediately. A visual check for nesting activity should happen before any cutting, whatever the month. Dense box and privet are popular nesting spots for dunnocks and wrens from late March.

   Adult box tree moths are on the wing from spring, and the RHS notes that overwintering caterpillars can be seen feeding as early as February on warm days. A pheromone trap, if you have box hedging, can show whether moths are in the area and how active they are, which gives early warning before the caterpillars are feeding. In 2024 the RHS reported almost five times as many box tree moth reports as in the same period of 2023, linked to a mild winter followed by a warm spring.

   Aphids become active on hawthorn (black bean aphid), viburnum and privet from mid-March in a mild Medway spring. Early colonies on young shoots are the easiest to deal with, either by hand-crushing or with a targeted spray. A single hedge can harbour a large colony by May if March goes unmonitored. For the full feeding and mulching schedule alongside these checks, see our Medway aftercare and feeding calendar.

3. May - June: peak caterpillar pressure and first box blight risk

   Box tree moth caterpillars are active from spring, and the RHS says most feeding damage occurs between March and October. The larvae spin webs across the foliage and eat from the inside of the hedge outward, so early damage is hidden. By the time you see the characteristic webbing and browning on the outer face of a box hedge, the caterpillars are already well established inside. Check the interior of the hedge regularly from early May onward, pulling sections apart to look for caterpillars and webbing before the outer face shows symptoms.

   Treatment: the RHS advises removing caterpillars by hand where practical, which is realistic on a short run of box. It also mentions a nematode-based biological control that has some effect on the caterpillars but can infect non-target animals, so it needs care. Check the product label and the RHS box tree caterpillar page for what is currently available to home gardeners before buying anything.

   Box blight, caused by the fungi Calonectria pseudonaviculata (formerly Cylindrocladium buxicola) and Calonectria henricotiae, is at its most dangerous in warm, humid conditions with overhead moisture. In a sheltered garden, a wet May or June can allow the disease to spread rapidly from a single infected plant to the entire hedge. Symptoms are brown patches on the leaves, black streaking on young stems, and rapid defoliation. Remove and bin (not compost) all affected material promptly. Do not handle infected plants and then healthy ones without changing gloves or cleaning tools. The RHS recommends against using fungicides on box blight, and says they are unlikely to be effective unless combined with other control methods, so prevention (clean tools, good airflow, clearing leaf litter) matters more than any spray.

4. July - August: second and third generations, continued vigilance

   The RHS says there are at least two generations of box tree moth a year, with a second adult emergence in late July or early August, and an extra generation is possible in a warm autumn. The nesting-season guidance period runs to 31 August, and the Wildlife and Countryside Act 1981, section 1 protects nests in use, which constrains what cutting can accompany pest management. You can remove obviously infested sections carefully, provided a visual nest check is carried out immediately beforehand, but a full box hedge strip-back is not possible in this window.

   Keep checking for caterpillars, and remove them by hand, while the pheromone trap is still catching moths. Keep monitoring the interior of box hedging rather than relying on the outer face. On hawthorn hedges through this period, woolly aphids can appear as white, cotton-wool-like patches on the stems. It weakens the bark and can create entry points for secondary fungal infections. It is rarely fatal to an established hawthorn hedge in Medway conditions but is worth squashing or treating with a targeted spray on a heavily colonised section.

   Box blight can resurge after summer rain following a dry spell. Keep clearing fallen box leaves from the soil surface around affected hedges, as the spores overwinter in leaf litter and reinfect the following spring. Do not blow or rake fallen box leaves toward healthy plants. For the clipping-timing side of box care alongside these checks, see our formal topiary maintenance calendar, which covers the correct cut windows for box, yew and shaped hedges through the year.

5. September - October: post-nesting assessment and autumn treatment window

   The 1 March to 31 August nesting guidance period has ended, but some birds nest later, so we do a visual check before every cut. September is the main annual cutting month for yew and several other hedges across Medway (see our Chatham cutting calendar for species-by-species timing) and the correct autumn window to assess the cumulative pest and disease damage from the season.

   On a box hedge that has had a difficult season with caterpillars or blight, the September assessment is the decision point: how much live growth remains, whether the structure of the hedge is intact, and whether the plant is worth the ongoing management effort. A hedge that has lost most of its volume to caterpillar feeding and blight in a single season may take several seasons to recover. The alternative, which is replacement with a blight-resistant and moth-immune species, is covered in our Medway species guide; suitable box alternatives for Medway conditions include Ilex crenata (Japanese holly), Lonicera nitida and Pittosporum tenuifolium, all of none of which is affected by box tree moth or box blight. Photinia x fraseri 'Red Robin' is another popular evergreen hedge that box tree moth does not attack, though it has its own autumn disease pressure from leaf spot (Entomosporium maculatum); see our Photinia trimming and disease management calendar for the treatment window and autumn prevention steps.

   Autumn is the time to tidy up after the season: check for blight symptoms, cut affected growth back to clean wood on a dry day and clear fallen leaves. It is also the window to remove pheromone traps and record the final season catch, which helps calibrate how aggressively to monitor the following spring.

6. November - December: hygiene clearance and year-end review

   Fallen box leaves on the soil surface are the primary source of overwintering Cylindrocladium spores that drive box blight the following spring. Clear them thoroughly from around all box hedges now. Bag the leaves and put them in the household bin, not the garden compost, as the RHS advises for infected box material. Even a partially composted pile of infected box leaves will release spores when spread on the garden the following year.

   This is also the window to review scale insect coverage on any hedges that showed heavy infestation in January, now that the foliage has thinned again. If scale numbers are high, prune out or wipe off the worst-affected stems and check current RHS advice on scale insect controls before applying any product.

   Review the pheromone trap catch numbers for the season and note which sections of the garden saw the highest caterpillar activity. Next year's monitoring can be concentrated there from late March. A season with high trap catches and heavy caterpillar damage is a prompt to be more vigilant next spring and to look closely at the most vulnerable sections from the first warm days.

Sources: Royal Horticultural Society, box tree caterpillar advice (rhs.org.uk/biodiversity/box-tree-caterpillar); RHS, 2024 box tree moth season forecast (rhs.org.uk/science/articles/2024-to-be-bumper-year-for-box-moth); Wildlife and Countryside Act 1981, section 1 (nesting-season offence, unlimited fine and up to six months custody per nest); David Domoney (Chartered Horticulturist, ITV Love Your Garden), "The Ultimate Guide to Box Hedge Care and Problems", YouTube, May 2024 (youtube.com/watch?v=49wGHoqzksQ); RHS, honey fungus identification guidance (rhs.org.uk); RHS, box blight information (rhs.org.uk/disease/box-blight).