I just thought I would let you know - every single one of the holiday variants you need is a bred-only variant. I would suggest that the next few holidays, you focus on breeding your current plants, and not picking up wild seeds. That's the only way you will get those variants.
Just remember that you aren't *guaranteed* a bred-only variant if you breed. You can try trading, but many people won't trade those away, because they're harder to get. One option is to trade a bred-only from one holiday for a bred-only from another holiday. If someone missed a holiday, occasionally they're willing to do this.
Yep I just noticed yesterday that we could still breed christmas trees/etc...so I'm doing that now I thought the events were over. It's hard to tell here.
