as it says on the packet that they deter whitefly.
How does this work?
Do they deter any other flies? (hoping somebody will say greenfly and blackfly).
Well, whitefly is the bain of the greenhouse tomato/cucumber grower.
For years now we have been growing marigolds, and planting them in the pots/growbags with tomatoes and cucumbers (about two per pot, or two per tomato/cucumber plant in a growbag).
The theory is that the marigold plants give off 'something' that the whitefly don't like. As the tomato/cucumber plants take this substance up into the plants the whitefly leave them alone. I'm sorry I can't be more scientific, but for all the years we have been doing this companion planting we have not been troubled with whitefly on our tomatoes/cucumbers.
As I say, not very scientific, but in our experience it does work. ;D
Try it,
valmarg
P.S. We've not tried it against green or blackfly,but it could work.
valmarg
I find that companion planting is better than using those pesticides any day of the week.
You get the best of both worlds, nice flowers and good veg to eat too.