I prefer to use tall narrow pots for seedlings, for larger and more mature trees wide pots are fine.

In my own experience, Citrus are NOT deep rooting (compared to say, palms).

I prefer deep pots for all ages of citrus because the perched water table is low relative to the roots and am less likely to get root rot due to roots sitting in soggy soil. I use deep tree pots (4" x 9") for all of my seedlings when I up pot.

ALL citrus do better with a medium that is wider, not taller.

So it’s good the roots shoot through the pot bottom exposed, and don’t touch the sides?

John, please tell me why "all citrus do better with a medium that is wider, not taller. "

The roots of a potted citrus will fill the pot regardless of its shape. If your pot is 1 foot diameter and 3 feet deep you will eventually get root wrapping in the bottom of the pot.

Citrus get 85% or more of their food and water from the first 18 inches of soil; and the feeder roots, which are generally at the drip line of the canopy, provide most of that. So, unless you want a tall, skinny tree, it is best to go wider, not deeper.

That is good info so my 1/2 wine barrels are ideal, thanks !

My trees' roots in deep pots have ample room horizontally and vertically.

I do not understand how one would get a tall, skinny tree if it is planted in a deep pot. Are you saying that trees in shallow pots get more nutrients than those in deep pots because the feeder roots are shallow?

This makes sense to me. Following along on the logic of root and canopy development, would it be a correct assumption that >>>

If you are going to plant the citrus in the ground, it would better to have a deeper rather than wider pot to develop those needed deep / tap roots.

If you plan to keep the citrus in a pot, the wine barrel (wider than deeper) is preferred.

George,

I would guess you are right, as most nursery bags are narrow and deep; but only if you plant it in the same size hole, thus encouraging the roots to grow (mostly sideways) in search of new food and water. Note that is only after the roots grow that the leaves and branches follow. With a long narrow pot/bag(, the roots will grow down (as in tap root); but more will grow sideways, Here is a photo of how our trees are delivered for planting; they are planted with a posthole digger at the same depth.