So I decided to try it out :-)
I have no red plastic Xmas balls so I used little red plastic apples, and since one of the tomatoplants is supposed to produce yellow tomatoes I hung up a few bunches of golden plastic grapes for good measure.
I dont know if it is going to help, but the result is rather cheerful :-)
the red things are the plastic apples, not tomatoes ! The tomatoes are still very small and green.
this is the one with the yellow tomatoes, and now also one red apple and two bunches of golden grapes :-)