Container size for blueberries and root depth

University of Maryland recommends containers that are 24 inches deep for blueberries. That sounds excessive considering their shallow roots. While researching the root depth I found this detailed description of root development at Oregon State University. Root depth is variable based on soil type and watering as quoted here:
“In sandy soils, roots will grow deeper than in clay or silt loam soils. In Florida, where a pine bark system is often used, blueberry roots will only grow in the upper pine bark layer, which has the preferred lower soil pH and a higher organic matter than the sandy soil below.”


My experience is blueberry roots grow to the bottom of the pot unless the bottom is too wet. That’s in pots up to 18 inches deep, mostly about 15 inches. I think they’d grow to the bottom of a 24 inch deep pot if the mix is good. If the mix breaks down and becomes anaerobic the roots in the bottom die.

15-24 inches would be a good depth. 24 is a pretty deep pot. 24x24 is what about 30 gallons maybe more. I’d not go shallower than 12 inches. To me that’s too shallow.

They form a solid rootball in good media all the way to the bottom.