Reading a nursery listing: seedling, sapling, caliper, bare-root and potted, and what a tree's age tells you

A nursery listing gives a young tree’s age and height, and its trunk’s thickness or its pot’s size. It says whether the tree travels bare-root, potted, or balled in burlap. Stem thickness and roots predict growth better than age or height, and seedlings of one age are graded apart on both. A listing seldom says whether the tree grew from seed, where the seed came from or whether it has had a systemic insecticide.

Seedling, sapling and 2-0

A seedling is a young tree grown from seed, and in nursery use one never transplanted. Foresters call a tree 2 to 4 inches thick at breast height a sapling. Our pages use both words for size: a pencil-thick seedling has about a quarter inch of caliper, a thumb-thick sapling about three quarters.

Forest nurseries give a bare-root seedling’s age as two numbers. The first counts seasons in the bed where the seed was sown. The second counts seasons in a transplant bed, where lifted seedlings grow on in wider rows. A 2-0 is two years old and has never been transplanted, and a 2-1 is three.

Caliper, height and pot size

Caliper is trunk diameter, taken at the root collar on a seedling. The American Standard for Nursery Stock measures a bare-root tree 6 inches above the root flare, and 12 inches up once the trunk reaches 4.5 inches there. In northern red oak, a thick stem at the root collar foretells how a seedling will do. Seedlings with ten or more large side roots also survived and grew better than those with four or fewer.

Height says less. One state nursery system cuts many hardwood tops to about 14 inches for shipping. Its red oaks average the same height at one year and at two, and the extra year shows in the stem. A pot size says least, and the standard calls one given without a plant size incomplete. A #1 pot holds from two thirds of a gallon to just over one. The watering calculator takes caliper at 6 inches above the flare.

Bare-root, potted or balled and burlapped

A bare-root tree is lifted from its bed while dormant and shaken free of soil, the lightest form to ship:

“Most mail order plants are of this class because plants in the soil are too heavy to ship economically.” (University of Maryland Extension, Purchasing Trees and Shrubs)

It also keeps about three times the roots of a balled-and-burlapped tree. In a Cornell street-tree study published in 2000, bare-root trees cost a third to a half less, and both kinds grew alike by the second season. It must be dug dormant, which is why our live plants ship in spring and fall, as our shipping page says.

A potted tree keeps every root and can go in outside the dormant season, with water. Roots that reach the pot’s wall circle it, and a root-bound tree can grow for years and then fail in a drought, so ask to see the roots. A balled-and-burlapped tree is dug from a field, heavy and costly, and its ball holds a small share of the roots.

What a tree’s age tells you

Age says how long the roots have grown, which matters most in trees that root first. A shagbark hickory seedling spends three years building a taproot 2 to 3 feet deep while the top grows only inches.

Age does not say how well a seedling grew, and graders sort each age by size:

“The minimum size for each species/age class is the smallest seedling deemed by reforestation staff to have a high probability of surviving and thriving after planting.” (Wisconsin Department of Natural Resources, Nursery Seedling Stock Descriptions)

Nor does more age at planting buy more growth later, since a small sapling often catches a big transplant. The growth estimator projects a sapling’s size at 10, 20 and 50 years.

What a listing seldom says

Three questions cover what the numbers leave out:

• Seed or graft. A grafted tree copies one selected tree, while a seedling carries genes from two parents, as seed source and provenance explains.
• Where the seed came from. Seed moved far north of its source can fall out of step with the seasons. We name the parent tree where there is one, as in the specimen lines.
• Insecticide. Neonicotinoids are systemic, and a soil drench can leave enough in the flowers to kill bees for months or years, as native trees for bees sets out.

Blue Whale Trees grows every plant it sells from seed, not grafted. Ask any nursery, us included, what its plants have been treated with.

Reading our own listings

A plant page names the form its saplings ship in and gives a sapling’s height and age with its price. An unpriced plant is not yet for sale online, and its page takes an email for one message when it is priced. To start:

• Saplings in the catalog, every plant we grow as a young tree.
• The shipping page, for the months live plants travel.
• Bare-root trees on arrival, for the day the box comes.

Common questions

What does 2-0 mean on a tree seedling?

It means two seasons in the seedbed where the seed was sown and none in a transplant bed. The seedling is two years old and has never been transplanted.

Where is caliper measured on a young tree?

On a seedling, at the root collar. On a larger nursery tree, 6 inches above the root flare, or 12 inches up once the trunk reaches 4.5 inches.

Is a bare-root tree better than a potted one?

Bare-root costs less and ships lighter but must be planted dormant, its roots never dried. A potted tree keeps every root and can be planted later in the season, but check that its roots have not circled the pot.

Is caliper the same as diameter at breast height?

No: a young tree’s caliper is taken at the root collar or 6 inches above the flare, and breast height is 4.5 feet up. Our growth estimator uses breast height on a tree that tall and caliper on a shorter one.

Sources

• Planting Hardwood Seedlings in the Central Hardwood Region: USDA Forest Service and Purdue University (P.M. Pijut, FNR-210, 2003): lifting by cutting the taproot and loosening the soil, root collar caliper for hardwood seedlings, root collar diameter as a guide to field performance, northern red oak seedlings with ten or more large side roots against four or fewer, and root-bound container seedlings that fail in drought years later.
• Seedling Stock Types: Minnesota Department of Natural Resources: the two-number age of bare-root seedlings, years in the seedbed and in a transplant bed, and transplants grown on in wider rows.
• Nursery Seedling Stock Descriptions: Wisconsin Department of Natural Resources: grading by a minimum size for each species and age, tops cut to about 14 inches for shipping and root-top balance, and the heights and calipers of one-year and two-year red oaks.
• Understanding Forestry Terms: A Glossary for Private Landowners: NC State Extension: a seedling as a tree grown from seed and as a nursery tree never transplanted, a sapling as a tree 2 to 4 inches thick at breast height, and breast height at 4.5 feet.
• American Standard for Nursery Stock, ANSI Z60.2-2025: AmericanHort (2025): caliper at the root collar on seedlings, 6 inches above the root flare on bare-root trees and 12 inches up from 4.5 inches, the volume range of a #1 container, and a container class alone as an incomplete specification.
• Watering newly planted trees and shrubs: University of Minnesota Extension: caliper measured 6 inches above the root flare, the rule the watering calculator follows.
• Purchasing Trees and Shrubs: University of Maryland Extension: why mail-order plants travel bare-root, planting them dormant, roots that must never dry, and root-bound container plants whose roots are seen before buying.
• Transplanting Success of Balled-and-Burlapped Versus Bare-Root Trees in the Urban Landscape: M.J. Buckstrup and N.L. Bassuk, Journal of Arboriculture 26 (2000): bare-root trees a third to a half cheaper than balled-and-burlapped ones with about 200 percent more roots, growth alike by the second season, and the risk of digging trees not fully dormant.
• Neonicotinoid Insecticides: Iowa State University Extension and Outreach (Laura Iles, 2025): neonicotinoids as systemic insecticides present in all of a plant’s tissues, and soil-drenched ornamentals carrying enough in their blossoms to kill bees for months to years.