Question: Must I always grow minis in small pots and standard varieties in large pots? I have very limited space, and would like to grow standards in small pots as well.
Answer: Again, the rule for proper pot size is to use a pot the same size as the plant’s root system. For minis and semiminiatures, this means pots of 2″ to 2 1/4″, and about 4″ for most standards (when grown as “house” plants, not for exhibition). Using pots that are smaller in size than the root system means that the plant will become “pot-bound” very quickly. These plants will need watering more frequently since the lesser soil volume in the small pot provides less water than the relatively larger plant and root system demands.
To keep soil fresh and to encourage new root growth, more frequent repotting into fresh soil would be necessary. That said, since the objective here is to keep standard-size varieties growing as small as possible in a limited space, keeping them underpotted would be advantageous. By constricting its root system, you would be doing the same as those who grow “bonsai”. In bonsai, plant size and growth are in large part regulated by restricting the size and growth of the root system.
Many violet growers are doing this when they grow mini and semimini varieties, that naturally would grow 4-8″ in diameter, in 1″ thumb-pots. These violets appear to be “micro” miniatures, since they grow only 2-3″ or so, in diameter. But these violets aren’t true microminiatures. Since it’s not their nature to grow this small, they are being “forced” to by constricting their root system. A true microminiature will grow small even when grown in a larger pot. Don’t be fooled by those violets in the cute little pots sold in your supermarket! Growing a standard violet in a smaller pot would have the same effect, but to a lesser degree, making it grow smaller, though not quite miniature. But if size is the issue, why not just grow miniatures?