Slit root ball when transplanting?
I bought 48 Soquel Redwoods from Costco. They're in 15 gal pots. I ended up buying the smallest trees I could find in the 15 gal because the 7 - 8 footers looked really really healthy while the much larger 12 footers, also in 15 gal, looked ashen and and really brown on the lower branches. Also some of the larger trees had split their pots open.
Also bought 15 Leyland Cypress. I really like the look of this tree but didn't want to risk having too many of them since they have so many issues like fungus.
First, does B1 really help with transplant shock. If so, when do you use it and how.
Secondly, when I slit open the pot and remove it from the root ball, the root balls on all the trees are pretty tightly packed and spiral tightly circled. A local tree nursury said to slit the root ball but don't open it up manually. He said slitting the root ball will help new roots push out. I was skeptical because if you do this, you're cutting a bunch of roots. That's got to hurt. However, it wasn't the first time I'd heard this advice.
If this really is the correct thing to do, can I slit both the plast pot and the roots all at once so I don't have to be so careful cutting the pot off?