[MrsPea]

I've just been down to the G/H to water the toms once again and found the plants covered in whitefly, has anyone else had this problem and what did you do ??

[JayG]

Some ideas HERE from the RHS.

Although I'm not completely sold on all the companion planting ideas I've seen, I do grow French Marigolds alongside my greenhouse crops and in the four years I've had the GH I've yet to see a whitefly - it may just be good luck, but possibly something for you to think about for next year. 

[mumofstig]

Tagetes work here as well 

[DD.]

I have some planted just inside the door.

[louiseyoungs]

So I guess I could just plant a marigold in a plot and leave it in the GH and hope that the peskies go for that or stay away?

[JayG]

Make sure it's a Tagetes rather than Calendula (pot marigold) type - Calendula won't do it for you, whereas Tagetes produce toxins in the stems and roots which do seem to work (at least until someone comes along and says their marigolds are covered in whitefly!  )

[MrsPea]

Thank you all, I went this morning to get some yellow sticky strips to hang up and that seems to of helped, I grew Tagetes last year why didn't I do it this year  never again

[Goosegirl]

Some ideas HERE from the RHS.

Although I'm not completely sold on all the companion planting ideas I've seen, I do grow French Marigolds alongside my greenhouse crops and in the four years I've had the GH I've yet to see a whitefly - it may just be good luck, but possibly something for you to think about for next year. 

Always works for me. The year my self-collected seeds didn't germinate, I thought pffft - and got whitefly! In my 12'x10' GH I plant four or five.