Got a problem in your plot? Let our Garden Guru Martyn Cox help you out

QI’ve got a 3ft-tall frangipani that I grow in a conservatory. Its leaf buds are covered with fine cobwebs that seem to cause foliage to drop early. I’ve sprayed with insecticide but it hasn’t made any difference. What do you think is the problem? Doreen McCole

AYour plant is almost certainly being attacked by red spider mites, which are tiny, sapsucking pests that thrive in warm, dry conditions. It’s tricky to treat this infestation with sprays, so why not try using an organic control containing larger, but harmless, predatory mites, such as phytoseiulus. A tube containing 200 mites (enough for a specimen plant) costs £6.95 from Defenders (defenders.co.uk).

QMy passion flower climber has produced fruit. Can I eat them? Nick Love

AThe orange fruit of Passiflora caerulea, the blue passionflower, are edible, but don’t taste nice. Edible passionflowers are unlikely to fruit unless grown undercover in the UK.