companion planting

I would like to try some companion planting next year - if for nothing else other than the bit of colour that it would bring to the plot.  This has possibly been covered elsewhere but I couldn't find what I was looking for.

Just wondering what seeds I should be adding to my list of veg seeds that I will need.  What goes with which veg.   Also do I sow companion plants direct or do I bring them on in modules (I start a lot of my veg in modules).  Do I need to increase planting distances for the veg if I am companion planting.

There's a comprehensive list of companion plants  here. LINK

If you start plants in modules, then start the companions in modules unless they're perennials already in place.

And yes, increase veg planting distances slightly to accommodate the flowers. You'll need to avoid planting tall companions with short veg though so the veg aren't shaded out.

Tagetes did well for me to combat whitefly in my poly.
Do you think it'll be any good to combat them against brassica's?
I'm gonna give them a try next season!

Slightly off subject, but the only time I have had whitefly in my greenhouse was after I had kept a hedgehog in there over the winter and it ate all the spiders. I think spiders work better than tagetes.