This is just one way. Works for planting during a drought, too.
Nice root system on this one. (Penstemon incertus from Agua Fria Nursery.) If the roots were coiled at the base, I would gently tease them apart with a fork (eating-type, remembering to wash it before eating with it, I guess) or a toothpick.
Planted. I dig as small a hole as possible. There isn’t any reason to dig a larger one.
Not a scene from Fringe. The roots have had most of the soil-less mix washed off by directing a stream of water at them from a watering can (not a hose; too easy to lose control).
Then the planting hole will be backfilled with surrounding garden soil. Naturally there will be some soil-less mix left in the hole, but the roots will be in contact with the garden soil, and have a good reason to check it out. Getting the plant established, that is, the roots growing into the surrounding soil, is the most critical factor in survival when planting in a dry garden or during a drought.
If the plant is planted in the ground without removing the soil-less mix, the roots will have no reason to move into the surrounding soil, and will simply continue to grow within the confines of the mix. I’ve planted trees and shrubs in my garden this way, and been able to pull them right out of the ground, root ball and all, even after several years in the garden.