Hi animalfarms,

No to your first question. The tree in which you graft your crab scionwood will not change the blooming time of the crab variety once it is healed and growing regularly. It may however, not bloom "on time" the first season following the graft, as it heals and begins to take. I am seeing this right now on some trees I grafted, using Hewe's crab scionwood.

I can't comment on your second question, but safe bet is someone else will.

'highbush cranberry' is not really a cranberry - it's a Viburnum(V.trilobum), and to my knowledge, not closely enough related to blueberries to anticipate success in grafting.

True cranberries(Vaccinium macrocarpon) are related to blueberries(also Vaccinium species), but I don't know whether they're graft-compatible, or whether your desire to grow & fruit them in zone 8 would come to fruition even if the graft was successful.