EING Head Gardener at East Donyland Hall I get to look after its large, Victorian lean-to greenhouse. I normally use it to propagate all our vegetable and perennial seedlings, but this spring is different.

The greenhouse houses two mature grapevines, one white muscat and one black grape. For the past two years they've been badly hit with powdery mildew. This fungal disease is encouraged by poor air circulation, dryness at the roots and crowded, overly-humid conditions. Despite my efforts the mildew has taken hold during the past two summers - so I'm determined this summer will be different!
To reduce humidity seedlings and cuttings will be raised in the greenhouse next door. I've also been scraping loose bark off all the vine's stems using a penknife. This will significantly reduce the nooks and crannies in which the mildew spores can overwinter. If your indoor grapes suffer from scale insect or red spider mite, this is also a handy method of reducing their numbers, too.

After scraping, all the loose bark was swept up then I sprayed the greenhouse with Jeyes Fluid. This will sterilise surfaces and leave nowhere for mildew to survive.

Opening windows and doors in summer and soaking vine roots during dry spells should finish the mildew off completely.