John Bryan asked about soil-warming cables in the open ground, which always sounds like wonderful luxury. I have come across it only once, in the garden at Waltham Place, a mile or so from where I write in Maidenhead west of London. The owners are the Oppenheimers, of De Beers fame, so they can afford it: just a shame they only grow hardy plants in those beds! (Canna & Tradescantia pallida, both of which in recent years at least can be regarded as hardy hereabouts.) John Grimshaw