Pot size

[Muhammad Arif Khan]

As you know I have been forced to container gardening. Where as a lot has been written about the potting soil little is available about the size of pot ideal for each plant. For me the ideal size is the smallest pot required for for the root system of the plant.Please fill me in with your findings.
My observation is:
Papilio Amaryllis roots will fill a 14 inch pot while eight inch pot is enough for other Hippeastrums.
Foot ball lily should be in a minimum of 14 inch deep pot and same is true for Lilium.
Six inch pot is big enough for Tagget.
What have you to add?
Arif

[khabbab]

I think an important consideration is whether the plant has shallow roots or not. In case of lilium, stem roots are important therefor you always urge to plant it deep. Now daylilies, magnolias, some gardenias have shallow roots so small pot will be enough. Plants with long tap roots (roses tend to grow tap roots) tend to struggle in small pots.

But should we start from small pot and then gradually increase or we should start from largest possible is a varied opinion. Some say putting a small plant in very large pot is not beneficial while some say that it gives more water reservoir available to plant.