Kim Wilde answers your gardening questions.
I live on a boat and really want to lay a lawn on the roof. Any advice?
Forget turf; this sounds like a job for Enviromat (01842 828266, enviromat.co.uk)- a living 'carpet' containing a mix of sedums that vary in height, colour and flowering season for year-round colour. The mat needs feeding yearly, with no mowing and minimal watering. A living carpet consists of four basic layers: plants, growing medium (ie, composted bark), drainage layer (ie, pea gravel) and waterproof layer (ie, asphalt). Check the flat roof on your boat is waterproof and, as there is no lip on it, perhaps some beading could be fitted around the edge. A barrier such as a polyethylene is advisable to protect the waterproofing from roots, with a moisture-retaining mat on top of it. After a sprinkling of slow-release granular fertiliser, the plant mat can then be laid.
How do I get my bougainvillea to spread over my balcony railings as they do in the Mediterranean? Also, how do I protect it in winter?
Bougainvilleas are grown not for their insignificant flowers, but for the brilliantly coloured, petal-like bracts that surround them. As a native of South America, it thrives in warm, light situations, preferring temperatures above 15C; however, it will tolerate as low as 5C, and even short periods down to 0C. I know of one plant in north London that has been trained as an espalier - that is, a central stem from which horizontal flowering arms grow at intervals. Perhaps you could do this on your balcony. In winter, the main stems are wrapped in horticultural fleece after the current year's growth has been cut back. Care is taken to keep the plant on the dry side until growth starts in spring. Pruning should be done lightly at the end of each flowering period, with major pruning in spring as growth starts: trim back to within a few buds of its main framework (bracts are mainly produced on new growth). Start watering in spring, and feed with a high-nitrogen liquid feed, then change to a high-potash one when flowering begins.