When does blight stop being a problem?????
Jane
Blight stops below 10C temperature. Don't keep the plants warm for as long as the weather is still growing weather and no frosts to kill the foliage. Keeping them dry is important. Well ventilated is important, not enclosed, but with a 'roof' over them. Don't tuck the plants in before frosts start because that makes blight worse and keeps moisture in.
Blight spores blow in, land on the plants but only get activated by consistent moist conditions. If you manage to keep the plants dry, spores cannot turn into blight. This will get more difficult when general autumn conditions increase humidity generally (more rain, misty or foggy starts to the day, shorter days with less drying sunshine). Drying off moisture and ventilation are the most important aspects as well as blight resistant varieties (over which you have no choice in this case). Good luck