Apparently the nursery trade goes by container class and size, not container volume

AMERICAN STANDARD FOR NURSERY STOCK

old gardenweb thread

scroll down to container specification table

Keep in mind that sizes for nursery stock have no bearing on the size needed to fruit or the size they will need to grow healthy in. Trees in nurseries are notorious for being root bound. Their biggest consideration is how small a pot can I get away with and still have a salable product.

Typically, plants grow to the biggest size their roots can support given the cultural conditions... so a bigger pot = a bigger plant.... Eventually!

Here's how it works...

Some nurseries may "Pot up" plants that didn't sell this past year -- so you start with a 1-year peach in a 12" pot... Then a 2 year old tree in a 15" pot... then a 3-4 year old tree in a 5-7 gal pot... and on it goes.... Unfortunately, they never have the chance to really stretch out their roots and grow big and strong... They gotta stay in that little bitty pot... They get kinda stunted like this.

But.. When you get a giant tree in an itty-bitty pot... Did they forget to pot it up bigger last year? Was it just extra-vigorous? Were those trees sitting around for 3 years and they finally clearanced them off?

When you get a little tree in a big pot... Did they just pot it up? Does it look root bound at all (Do you find a little bound rootball up inside a giant pot full 'o dirt?)

Also consider that some plants need a deep pot for deep tap roots (Pecans, Hickory, and Chestnuts are good examples).... while others need very shallow pots for very shallow root systems (like Azaleas and Dogwoods)....

So.. you when you see a dogwood in a deep pot -- take consolation that there won't be any roots in the bottom half of it..... and when you see a Pecan or Chestnut in a shallow pot... its tap root is bound up (Or cut) and it won't ever grow right.

Thanks

John

It may seem that one took almost 5 years to reply..if the 10 after the date = 2010.... but... just arrived at Garden Web

Should the original poster person read this.. r anyone else with a similar question.... see if this direstion may be an answer

Do not order plants (trees, shrubs, et. al.) just by thier container size.
Specify the size of the plant and if it should be in a container, box, BR (Bare Root), B&B (Balled and Burlaped), etc.

For example.
A low spreading plant. For example,
Juniperus horizontalus Wiltoni.
ask for say 3 Gal 15-18" spr (Spread)
An upright shrub. For example
Buxus microphylla x koreana Green Mountain
ask for say 3 Gal 18-21" or 24-28" B&B

Before you buy from a nursery or garden center...
look at the quality of the plants there.
Look at the quality they sell...
Evaluate the people who work there...
The care given the nursery and it's customers...
Select your source as well as your plant(s)

John said it all....

Just to further complicate things a bit...then you have root pruning containers. The nursery economics on these are different so you don't see a lot of them but if you can find them you are dealing with a horse of a different color.

The problem with many trees (especially the deeper tap rooted ones) is that root will j-hook or circle with traditional containers. Root pruning containers prevent this by air pruning the tap root causing early secondary and tertiary branching. Containers are upsized by about 4" per side when the roots fill the container and the pruning process begins again. You can end up with much bigger more vigorous trees in smaller containers this way. The biggest issue is that while the root system is much more efficient at collecting water and nutrients since there are many more terminal roots, they can only collect it from the area they reach. This means you generally need to provide supplemental water for the first year until the trees are well established and the roots reach well into the native soils.

Will all of the above posts are good information that apply to most container grown trees, I just wanted to point out an exception.

I've been using a root pruning container system in my basement to start long tap rooted trees indoors under lights in the winter and then keeping them for 1 or 2 growing seasons in larger air pruning pots before planting them. So far, I'm pretty impressed with the results but I only have a few years under my belt.

Keep in mind that sizes for nursery stock have no bearing on the size needed to fruit or the size they will need to grow healthy in. Trees in nurseries are notorious for being root bound. Their biggest consideration is how small a pot can I get away with and still have a salable product.

VERY true !!