Gardening Services Near You in Canonbury

Behind a good many N1 houses there is a flat or shallow-pitched roof over a rear extension, a bin store or an outbuilding, and over the last decade a sizeable number of those have been given a living surface. A sedum roof is not decoration and it is not a garden in the ordinary sense: it is a shallow, deliberately impoverished system that works only while its substrate stays thin, its drainage stays clear and nothing woody gets established in it. Left alone for four or five years, most of them fail in the same predictable sequence.

What is actually up there

Under the plants is a layered build-up: waterproofing, a root barrier, a drainage and reservoir layer, a filter fleece, and then between sixty and a hundred millimetres of growing medium that is mostly crushed lightweight aggregate rather than soil. That thinness is deliberate. It limits weight, and it keeps conditions hostile enough that drought-tolerant sedums and sedges hold their ground while more vigorous plants cannot. Adding compost to make it look healthier is the single most common way of ruining one.

The seedlings that end a roof early

Everything that blows about an inner London garden lands up there. Birch, buddleia, sycamore and willowherb germinate readily in an open mineral surface, and within two seasons a woody seedling has a root system heading for the membrane. Two weedings a year, in spring and early autumn, working on hands and knees rather than with any tool, is what keeps a roof alive; the seedlings pull easily while they are small and become a problem the moment they are not. Ordinary weeding of this kind belongs with the wider upkeep covered by Barnsbury gardening services.

Feeding a system designed to be poor

A thin mineral substrate holds few nutrients and loses them to every rainfall, so a sedum mat thins, reddens and develops bare patches after a few years. A single controlled-release application in spring, at a low rate and specified for this use, restores it. Lawn fertiliser must not be used, because the nitrogen level favours grasses and coarse weeds, which then shade out the sedum and leave a roof that is neither one thing nor the other.

Outlets, margins and standing water

The gravel margin around the edge and around every outlet is there to let water off, and it fills with sedum, leaf litter and grit until it does not. A blocked outlet leaves standing water, which kills sedum quickly and adds weight the structure was never intended to carry. Clearing outlets, keeping margins free and checking upstands and flashings is the part of a visit that actually protects the building, and it matters most in autumn when leaves are falling. Anything washed off the roof arrives on the paving below, which is cleaned by a local pro near you.

Drought, access and the limits of the job

An established sedum roof is not watered; it shrivels in a hot summer and recovers. A newly laid one needs water through its first two summers or it never establishes evenly. Access is the real constraint, since safe working on a roof at first-floor level needs proper edge protection rather than a ladder and optimism, and a wet sedum mat is slippery. Anything involving the waterproofing itself is a roofing matter, not a gardening one. Where a roof abuts a neighbour's wall it also gives rodents a dry undisturbed run at first-floor level, and once that reaches a loft it becomes a matter for the pest control team in Canonbury.

How visits are arranged

Two visits a year suit most of these roofs, one in spring for weeding and feeding, one in autumn for outlets and leaf clearance, quoted on area and on how the roof is reached. Substrate, plugs and arisings usually have to pass through the house, and organising that properly rather than improvising on the day is worth doing; moving materials of that kind is arranged through Hoxton man and van services. The way a seasonal round is put together is explained on garden maintenance services UK.