Though "hostas" are often thought of as a single entity, differences in growth rates between varieties require specialized techniques. At the same time, other perennials require growing methods specific to their needs. Time of year also influences how a plant is handled. Generally, plants potted beyond mid-summer must be handled differently than those potted earlier. Our information reflects some of the knowledge that we've gained in these areas over fifteen years of growing our liners and 2 1/4" plants into saleable quart or gallon-sized plants in outdoor beds.
The final pot size depends upon the mature size of the plant. For example, a huge plant like 'Sum and Substance' would best be grown in a two-gallon container while quart containers work better for dwarf hostas such as "Tiny Tears.' The soil mix we've used has been a fairly standard peat-perlite blend-good aeration and moisture retention.