All Species Except Cottonwood
For the various willow species and as well Red-osier dogwood, beds plants five plants wide (if 2-gallon potting bags are used), or six bags wide (if 1-gallon bags are used), work fine.
If beds are located with an east-west orientation, cuttings on the south side can also be pruned a slightly shorter to further reduce mutual shading.
Note also that all shoots lower on the cutting have been pruned off. This causes the plant to focus shoot grow on the top. Do this when the shoots are still small by grabbing the stem and running your hand up and down.
Here the planting bags can be tightly spaced.
Construct the bed a few inches wider than five bag widths so there is still room for five per row even if a slight space is left between some of the bags.
I have had some trouble growing cottonwood TRS Cuttings as this species does not seem to tolerate any mutual shading. For this reason I recommend this species be planted only three plants wide, and also that a space be left between the rows as well.
With new shoot growth, even the smaller plants here will be at least 1.5 m in height.