They will stiffen a lot when dry.
With dogwood, plum, and other hard shoots (less so, willow) I usually reduce the front end of all the shafts to consistent diameter. My reasoning is that, when you flex a shaft to measure spine, where does it flex the most? The middle, right? So taking some off the front won't change spine, much. Also, if I pick a bunch and measure the tail end, that is a good start toward consistency.
I have a hardwood board with an 11/32 hole drilled in, and a 23/64 hole, and a 3/8", and some notches same size, etc. So, I peel the bark, dry them, etc. Then, I measure by sticking the tail in one of the holes in the board. I cut it off where it stops. Then I cut to length, plus an inch, The point ends will be about 3/8" on the red osier I use the most.
Now, they won't all taper the same, point end is biggest, but it tapers, too. I take a crayon or charcoal, and color the 3" of the tip of the shaft. Then use a scraper, like a pocketknife, to scrape it until the crayon is gone. Then color 6" of the shaft and scrape that off. Check that front end diameter. Do this until the shafts will all fit the front 1/3rd of their length into the 23/64 hole.
Then put in nocks, do your heat straightening, and start your bare shaft tuning.