Whitefly wipeout
Q How do I get rid of whitefly?
A Whitefly can’t overwinter as eggs in an empty greenhouse so if you only grow summer crops and get rid of all the weeds, there should be nothing for the pests to overwinter on. Make sure you properly clean the greenhouse this winter and disinfect glass and other surfaces. Check over new plants very carefully before introducing them and squash or spray any pests you find.
Outdoors, blast them with the hose or a suitable insecticide. Organic sprays include pyrethrum, fatty acids and plant oils.