What Is Up With Nursery Plant Sizing?!
If you’re browsing our site and thinking, “Why are there so many sizing options... and why don’t they match how big the plant looks?” you’re not alone. Nursery plant sizing can feel confusing, especially when you’re comparing container sizes, liter measurements, caliper, and height all in one place.
Plants aren’t sized the way most products are. Instead of being labeled by how tall or full they appear, nursery plants are sized using industry and state standards that focus on things like root volume, trunk diameter, or overall height. These standards exist to create consistency and fairness, even though plants themselves are living, growing, and naturally variable.
This guide breaks down the sizing terms you’ll see on our site so you can shop with confidence and know exactly what you’re getting and why it’s labeled that way.
Quick Guide: Sizing At A Glance
Container Sizing
Container sizing is based on the volume of the plant's soil and root mass. Because container sizing is volume-based, the dimensions of the pot or size of plant can vary.
Example: A product labeled 10.44L Container is a plant that has 10.44L (or 2.8 gal) of soil and root mass.
B&B Sizing
B&B Trees are measured either by their caliper or their height.
Caliper: The diameter of the tree's trunk.
Example: A product labeled 1.2" Caliper B&B has a trunk that measures 1.2 inches in diameter.
Height: Measured from the base of the trunk at the soil line to the top of the tree.
Example: A product labeled 6' Tall B&B measures 6 feet from soil line to top.
What Is A Clump?
"Clump" or "Clump-Form" trees have more than one stem or trunk. Clump form trees are primarily measured by their height.
Example: A product labeled 8' Tall B&B (Clump) has multiple stems and measures 8 feet from soil line to top.
Container Sizing Explained
Container sizing is not based on the height of the plant or the outside dimensions of the pot. Instead, it reflects the actual volume of soil and root mass inside the container. This system exists because nursery pots can vary in shape and size, even when they hold the same volume.
Colorado follows industry and regulatory guidelines that require container-grown plants to be sold by root/soil volume, expressed in liters, rather than by pot appearance or plant size. This helps customers make accurate comparisons and know what they’re purchasing.
What does volume sizing tell you?
The liter (L) size gives valuable insight into:
- The established root system
- The plant’s ability to handle transplanting
- Expected establishment and growth potential
Container Sizing Conversions
| Nursery Size | Metric | U.S. |
|---|---|---|
| #1 | 2.48L | 2 Qt |
| #2 | 6.19L | 1.6 Gal |
| #3-5 | 10.44L | 2.8 Gal |
| #6-7 | 15.65L | 4.1 Gal |
| #10 | 33.72L | 8.91 Gal |
| #15 | 46.78L | 12.4 Gal |
| #20 | 86.98L | 22.98 Gal |
| #25 | 104.50L | 27.6 Gal |
Examples Of Container Size
Wondering what these container sizes look like in real life? Take a look at our staff members posing by some of our container selections:
2.48 L or #1 Containers
15.65 L or #7 Container
10.44 L or #5 Containers
46.78 L or #15 Containers
33.72 L or #10 Container
B&B Sizing Explained
Balled & burlap (B&B) trees are field-grown trees that are dug with an intact root ball, wrapped in burlap, and secured for transport and planting. Unlike container-grown plants, B&B trees are not sized by soil volume. Instead, they are sold based on caliper or height, depending on the type and size of the tree.
Caliper sizing
Caliper refers to the diameter of the tree’s trunk and is the most common sizing method for deciduous shade and ornamental trees.
Caliper is a reliable indicator of a tree’s maturity, strength, and structural development. A larger caliper generally means a more established tree with a thicker trunk and more developed branching structure.
Height sizing
Some trees, especially evergreens and certain specialty trees, are sold by overall height instead of caliper. Height is measured from the base of the trunk at the soil line to the top of the tree.
Height-based sizing helps customers understand the immediate visual impact of the tree in the landscape, particularly for screening, windbreaks, or privacy plantings.