Shallow = wider pot then tall, less then 6in in height.
Deep = taller pot then wider, 12in or taller
Considering those dimensions, I would go with the 12" deep pots, unless they're 3" wide. A wide, 6" deep, pot won't be offering a benefit.
The deepest you'll need is around 18"-24". From there, you want a wide pot, as most of the rooting structure are "surface" roots, and those are where a majority of the nutrient uptake occurs.
In a, poorly named, 1 gallon pot, you can grow a decent sized bush. I've seen them used for starting plants indoor (to be planted in the ground, outdoors) that got up to 2' tall when pruned for height. A five gallon bucket can grow a plant that's suitible for a tiny hedge, but lacks the width to make use of all the soil.
The deepest you'll need is around 18"-24". From there, you want a wide pot, as most of the rooting structure are "surface" roots, and those are where a majority of the nutrient uptake occurs.
In a, poorly named, 1 gallon pot, you can grow a decent sized bush. I've seen them used for starting plants indoor (to be planted in the ground, outdoors) that got up to 2' tall when pruned for height. A five gallon bucket can grow a plant that's suitible for a tiny hedge, but lacks the width to make use of all the soil.
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