Sweet Bell Help?

[ACEHearts]

I am once again growing sweet peppers in my garden, this year upping my plant out substantially in an effort to be able to do most of my canning from the garden, without needing to run to the farmers market for peppers.

In past years I've had limited success with bell peppers (vs the jalepeno's I grew a couple years ago that left me completely swamped!). I know this year I'm planning on putting black plastic down to help the soil warm up early, and will work to keep them mulched. Are there some other tips/tricks that would help, especially with our very short season here (Cdn zone 5b, approx US z4, my growing days are 139 based on average frost dates).

I'm planting several varieties (most are traded seeds, so I only have what is written on each packet)
California Wonder
Red Bell
Sweet Red
Sweet Italian
Gypsy Bell
Yellow Bell
Orange Bell

Looking forward to any tips/tricks to help these be as productive as possible (oh, and this list doesn't include the chili's.. that's a whole other list! LOL!!)

Thanks!
Cindy