Kim Wilde answers your gardening questions.
I have a large Rhus (sumac) which is sending up suckers all over my lawn and flowerbeds, and is also affecting my neighbour's garden. I would like to cut it down in the autumn and try to kill off the whole root system once and for all. Is this possible?
When you cut it down this autumn, apply Deep Root (available from garden centres) to the cut edges and rainproof them, by covering with a plastic bag. Any suckers that come up should be cut down to about 10cm and treated in the same way. Rhus are beautiful shrubs, with exotic-looking pinnate leaves and sensational autumn colour, so try to save some of the suckers and pot them up to enjoy as a container plant. I remember admiring a container-grown Rhus at Hidcote. There, they top-dress the container each spring by removing the old compost down to the surface roots and adding fresh. Do handle Rhus with caution: the sap can be an irritant to the skin, so wear gloves.
Is it safe to eat vegetables produced within a raised bed, made from railway sleepers that exude creosote? I have delicious tomatoes, kale, peas, artichokes and rocket, but worry that I'm poisoning myself.
In 1999, the European commission banned the sale and use of creosote, and the environmental protection agency has decided coal tar creosote is a probable human carcinogen. There are some worrying studies that point to chronic health effects associated with creosote, as well as ecological implications. Coal tar creosote components may be found in the soil as a result of seepage from treated timber, so I would recommend that you replace your railway sleepers and not eat your produce this year. Alternatives, such as recycled plastics or even concrete sleepers, which look very realistic, are now on the market. Oak, sweet chestnut and western red cedar last up to 20 years in contact with the ground, larch about 10 years and pine around five. Other options include breezeblocks, bricks, stones and reclaimed floorboards. Contact the organic organisation HDRA for more information.