Thorny problems: should I returf my lawn?

Weeds in a gravel drive

Q Last year we renovated and extended our weedy gravel drive. Some of the area was lined with a membrane before a thick layer of coarse gravel was spread on it, while other parts (where there is less traffic, and where much of the original soil had been removed or churned up badly during some major building works), we didnt bother. Almost straight away, weeds (including thistles) started to appear, even on the areas with the membrane. What now?

Jacqui Harman, via email

A The areas that have simply been gravelled over the top of the disturbed soil will have naturally sprouted an enormous amount of weeds, seeds of which will have lain dormant in it for years. Creeping thistle and dock are extremely tenacious perennials, notorious for spreading around in disturbed, infertile soil.

The weeds that are showing up where you really didnt expect them in places where you laid the membrane are possibly growing through gaps where the membrane has become damaged by car traffic, or where it was not overlapped sufficiently. In any event, over time a layer of silty soil builds up on top of membrane, enabling determined weed seedlings to germinate and thrive, so you may always have a bit of a problem, despite your efforts.

When growth really kicks off next month, you can treat all the weeds in the gravel with one of the long-lasting weedkillers that contain glyphosate, to hit the current crop of visible weeds, both annual and perennial. Some of these products also contain chemicals that will inhibit the future germination of seeds for up to three months, although I suspect this is a bit optimistic where deeply gravelled drives are concerned. The products available to gardeners are Path and Drive Weedkiller (from Bayer Garden) or Pathclear (from Scotts), and both can be found in garden centres. These are strong chemicals and instructions should be followed carefully: They should not, for example, be used on sloping land (where there is a danger that the weedkillers will drain onto flower beds or grass), but once they are dry, children and pets need not be excluded from treated area.

Use weed killers on gravel carefully to prevent killing flowers and grass

Reassurance

Q Val Groves is worried about random little fungi that have appeared in her garden, presumably from a delivery of mulch that was spread about her borders during the course of a makeover. She asks if the fungi will harm her new plants, and if so, how she can rid her garden of them.

A Nearly all fungi that appear in gardens are harmless to plants, growing naturally from organic matter in the soil (or as in Vals case, from organic matter brought in from elsewhere). If they offend, they should just be brushed away or forked into the soil. Notable exceptions are honey fungus that travels via very distinctive underground rhizomorphs from dead hosts to live woody plants. They also throw up crops of orange toadstools from the roots of affected trees and shrubs. To hinder its spread, all dead woody plants and as much of their root as possible should be dug out and burnt. The other garden baddie that can spread from dead to living woody plants is coral spot rot (showing as crops of small orange pustules on the dead branches of, for example, acers and chaenomeles). Swift removal and disposal of affected branches will prevent airborne spores from hanging around.

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Thorny problems: should I returf my lawn?