Common garden problems
Discover how Flourish Landscaping can help you in your garden
Common garden problems
Identifying causes, finding solutions
Most garden problems have a root cause that, once identified, can be addressed properly rather than managed repeatedly. Whether it is waterlogged soil, persistent pests, failing planting, or a lawn that refuses to recover, the solution usually lies in understanding what is happening beneath the surface rather than treating the symptom alone.
Our team brings a horticultural qualification and decades of practical experience to every site visit. We diagnose accurately, recommend honestly, and carry out work that resolves the problem rather than delaying it. If you would like us to assess your garden, get in touch to arrange a visit.
Waterlogged and flooded gardens
Waterlogging is one of the most common and most damaging garden problems across South West London and Surrey. The underlying London Clay retains water rather than draining it, and once saturated, it can take days or weeks to dry out sufficiently for plants, lawns, or paving to recover.
The signs are familiar: standing water that persists after rain, squelchy or muddy lawns, moss replacing grass, borders smelling sour, and plant roots rotting despite healthy top growth. In paved areas, pooling water near the house or along fence lines indicates falls that are not directing water away from the structure.
The cause is almost always in the soil profile or drainage infrastructure rather than the surface. Common causes include:
- Clay soil that has compacted and lost structure, reducing the rate at which it can absorb water
- Blocked or collapsed soakaways that are no longer functioning
- Paving laid without adequate falls, trapping water against walls or in low spots
- Raised ground levels from building or landscaping work that have altered the natural drainage pattern
- High water tables in low-lying or riverside plots
We have a dedicated page on flooded gardens covering our full range of drainage solutions, from French drains and soakaways to sub-surface drainage networks and soil re-engineering. For a recent example of drainage work in Surrey clay conditions, see our large garden drainage project in Cobham.
Lawn problems
Lawns are often the most visible indicator of a garden’s overall health, and they are disproportionately affected by the clay soils common across our area. The most frequently occurring issues are:
Moss and thin grass
Moss thrives where grass struggles, in compacted, poorly drained, or heavily shaded conditions. It is a symptom, not a cause. Treating moss with iron sulphate resolves the visible problem temporarily, but unless the underlying conditions are improved, it returns within a season. Aeration, scarification, overseeding with a suitable grass mix and, where drainage is genuinely poor, a proper sub-surface drainage solution are the steps that deliver lasting improvement.
Uneven surfaces and settlement
Lawns on clay soils are susceptible to heave and settlement as the soil shrinks and swells with changes in moisture. Uneven surfaces can also result from previous landscaping work, tree root activity, or mole damage. Where the unevenness is cosmetic, top dressing and overseeding is usually sufficient. Where it reflects a deeper drainage or structural issue, addressing the cause first prevents the problem recurring.
Patchy growth and bare areas
Patchy lawns are usually caused by a combination of compaction, shade, drought stress, or heavy foot traffic. Persistent bare areas near trees or along boundaries are often a root competition issue rather than a lawn management problem. We assess each situation individually rather than applying a standard treatment, the right response depends on the cause.
Our garden maintenance programmes include scheduled lawn care, feeding, scarification, aeration, and overseeding, timed correctly for the growing season.
See our garden maintenance service for ongoing lawn care, or our garden advice section for guidance on specific lawn conditions.
Pest damage
Pest damage in gardens across South West London and Surrey ranges from minor nuisance to serious structural harm, depending on what is affected and how quickly it is addressed.
Vine weevil
Vine weevil (Otiorhynchus sulcatus) is one of the most damaging soil-based pests in UK gardens. The larvae feed on roots through autumn and winter, often killing container plants and border specimens before any visible sign appears above ground. Adult weevils notch the leaf margins of a wide range of ornamentals from spring through summer. Biological controls using nematodes (Steinernema kraussei or Heterorhabditis bacteriophora) are the most effective long-term management approach, applied at soil temperatures above 5°C.
Slugs and snails
These are particularly damaging in shaded or north-facing gardens where moisture levels remain high. The most effective management combines physical barriers, habitat reduction, removing debris and dense ground cover where slugs overwinter, and encouraging natural predators including hedgehogs, ground beetles, and birds. Plant choice is also relevant: selecting slug-resistant species such as ferns, Brunnera macrophylla, and hellebores in vulnerable areas reduces damage without requiring repeated chemical intervention.
Aphids
Aphid colonies on roses, Viburnum, and soft-stemmed new growth are common from spring onwards. Where infestations are identified early, a strong water jet or the introduction of ladybird larvae (Adalia bipunctata) is effective. Persistent infestations, particularly on established shrubs, may indicate that the plant is under stress from other causes, such as drought, poor nutrition, or restricted roots, that make it more susceptible.
Box blight and box moth caterpillar
Both Cylindrocladium buxicola (box blight) and Cydalima perspectalis (box tree moth caterpillar) are now widespread across Surrey. Box blight presents as brown patches and defoliation, with white fungal growth on the undersides of affected stems in humid conditions. Box moth caterpillar strips foliage rapidly and can defoliate an established hedge within weeks. Where box is central to the design and the client wishes to retain it, a management programme combining fungicide treatment for blight and pheromone traps or biological controls for the moth can be effective. Where box is to be replaced, Ilex crenata, Pittosporum tenuifolium ‘Tom Thumb’, and Taxus baccata are reliable evergreen alternatives for clipped structure.
Plant disease
Fungal diseases
Fungal diseases, including powdery mildew, rose black spot (Diplocarpon rosae), honey fungus (Armillaria species), and phytophthora root rot, are among the most common plant health problems in this region. Correct identification is essential before any treatment is applied, as the response to each differs significantly. Honey fungus, for example, has no effective chemical treatment, the response is careful removal of infected material and replacement with resistant species. Phytophthora typically indicates waterlogged or poorly drained conditions, and the soil environment needs addressing alongside any plant replacement.
Bacterial and viral problems
Bacterial canker affects stone fruits including Prunus species, presenting as sunken, oozing lesions on stems and branches. Viral diseases, most commonly mosaic viruses affecting ornamental and edible crops, are spread by sap-feeding insects and have no cure, infected material should be removed and disposed of away from the garden. Correct identification avoids unnecessary treatment of non-infectious conditions that can resemble disease symptoms.
Soil and nutrient problems
Surrey’s London Clay soils are fertile but structurally challenging. They drain poorly when compacted and waterlogged, crack when dry, and can be nutrient-limited in newly landscaped areas where topsoil has been stripped or where drainage installations have disrupted the soil profile.
Compaction
Compacted soil restricts root growth, reduces drainage, and limits the uptake of nutrients and oxygen at root level. It is most common along pathways, in frequently trafficked areas, and in gardens that have been heavily worked without organic matter being returned to the soil. Core aeration, deep cultivation where appropriate, and the regular incorporation of organic matter are the practical responses.
pH imbalance
Clay soils in this region are typically slightly alkaline. Certain plants, Rhododendron, Camellia, and Pieris, require acid conditions and will show yellowing foliage (chlorosis) when grown in neutral or alkaline soil, even where nutrition appears adequate. A soil pH test identifies this quickly. Where acid-loving plants are part of the brief, raised beds with ericaceous compost, or sourcing more pH-tolerant alternatives, are the practical options.
Nutrient deficiency
Yellowing foliage, poor growth, and weak flowering can all indicate nutrient deficiency, but the cause varies depending on which nutrient is limited and what the soil type is doing. Nitrogen deficiency causes pale, yellowing growth throughout the plant. Iron deficiency, often on alkaline soils, causes interveinal chlorosis, yellowing between the leaf veins while the veins remain green. Magnesium deficiency causes similar symptoms, particularly on roses. A soil analysis, rather than a broad-spectrum fertiliser application, identifies exactly what is needed and avoids overcorrection.
For gardens where poor soil is the core problem, our planting design and installation service includes soil preparation and improvement as a standard part of the process. Our hard and soft landscaping service covers groundworks and soil remediation as part of wider garden builds.
Weed problems
Weeds are a symptom of open soil rather than a failing of management. The most persistent garden weeds in Surrey gardens are those with deep or spreading root systems that regenerate from fragments left in the ground.
Persistent perennial weeds
Bindweed (Calystegia sepium and Convolvulus arvensis), ground elder (Aegopodium podagraria), horsetail (Equisetum arvense), and Japanese knotweed (Reynoutria japonica) are the most challenging. All regenerate from root fragments and require either sustained removal over several seasons or, in the case of Japanese knotweed, a formal treatment and management programme. Japanese knotweed has legal implications for sale of property, and some mortgage lenders require a management plan as a condition of lending, so early identification and professional treatment is important.
Annual weeds
Annual weeds, including hairy bittercress (Cardamine hirsuta), groundsel (Senecio vulgaris), and shepherd’s purse (Capsella bursa-pastoris), are best managed through a combination of regular surface cultivation and mulching. A well-applied organic mulch layer, minimum 75mm, suppresses germination effectively and reduces the time needed for weed management considerably.
Our garden maintenance programmes include structured weed management as part of the annual programme, rather than as a reactive task. See also our guide to low-maintenance garden design for design-led approaches that reduce weed pressure from the outset.
Paving and hard landscaping problems
Many of the hard landscaping problems we are called to assess are the result of installation shortcuts taken at the build stage, insufficient sub-base depth, incorrect mortar specification, inadequate drainage falls, or timber structures built without proper moisture management.
Settlement and movement
Paving that sinks, tilts, or becomes uneven after installation almost always reflects a sub-base that was not compacted properly, was too shallow for the load and soil conditions, or was laid without accounting for the movement characteristics of clay soil. On Surrey clay, a minimum 150mm compacted MOT Type 1 sub-base is our standard for residential patios, and on heavier-trafficked areas or where drainage is poor, we go deeper. Patios laid on builders’ sand without a proper base will settle on clay soils, guaranteed.
Pointing failure and joint erosion
Failed pointing allows water ingress, frost damage, and weed establishment in joints. Resin-based or slurry grout pointing is significantly more durable than traditional sand-and-cement in exposed conditions. Where pointing has failed across a large area, a repoint is often more cost-effective than piecemeal repair.
Decking deterioration
Decking that is cupping, splitting, or becoming slippery is usually suffering from one of three problems: inadequate ventilation beneath the boards leading to moisture retention, incorrect joist spacing causing boards to flex and crack, or untreated or poorly maintained timber. Our decking installations are built with correct joist centres, ventilation gaps, and fixings to manufacturer specification, and the structures that fail prematurely almost always have one of these elements missing.
For new paving, patios, and paths see our patios, paths and driveways service. For new decking see our decking page.
Fencing and boundary problems
Failed fencing is one of the most common call-outs we receive, and the cause is almost always the same: wooden posts set in concrete directly into clay soil, without adequate depth or drainage, that have rotted at the base.
Clay soil holds moisture around timber posts, accelerating decay. Posts without gravel boards allow panel bottoms to wick moisture from the ground. Posts set too shallowly in clay, which shifts seasonally as it wets and dries, will lean and eventually fail regardless of the panel quality. Our fencing team, led by Trevor with 40 years of specialist experience, sets concrete posts with gravel boards as standard on clay soil installations. It costs more at the outset and lasts decades longer.
See our garden fencing and screening page for full detail on materials, specification, and the 10-year workmanship guarantee we provide on all fencing installations.
When a garden needs more than maintenance
Some garden problems are symptoms of a design that is no longer working, a layout that has never suited the space, planting that has outgrown its position, or a garden that was built to a low specification and is failing as a result. In those cases, the most practical and cost-effective response is a redesign rather than ongoing remedial work.
Our garden design and build service addresses all elements, design, construction, and planting, as a single coordinated process. Our full range of landscaping and garden design services covers everything from concept design through to aftercare.