Understanding Nursery Stock Sizes

There’s no universally agreed upon unit of measurement for nursery stock. The common sizes for plants are caliper, container size, and height (inches or feet). In any of those 3 sizes, it’s safe to equate a small number (or lower size) with age, weight, and price. We do our best to continually stock a range of sizes for any one species; however, not all sizes are always available. To help make sense of all the options, let’s start small and work our way up.

understanding nursery stock sizes plant containers in a row

Nursery Stock: Containers

Container Grown Trees are very popular these days, but not all container sizes are equal. Containers are light-weight, easy to transport in bulk, and allows us to offer certain trees outside of standard harvest dates. A lower container number (i.e #5 Container) generally means a younger, lighter weight, and lower price plant. And vice versa, a larger container number (i.e #25 Container) generally means the plant is more mature, heavier weight, and higher price.

understanding nursery stock sizes propagated plants measured in container sizes

A quick note about containers. The term “gallon” is a moniker carried over from the past when growers used to grow plants in milk jugs. Although still commonly used to describe the size – it’s not technically accurate. Nursery containers are not volumetrically accurate to milk gallons. In addition, container manufacturers often have different sizes for the same container, meaning the size of an empty #10 container may vary slightly among manufacturers.

Container Perennials

You will find perennials in sizes as small as Pint and as large as #5 containers. A #1 container is the most common size for perennials. Perennials are only available in container sizes.

Container Trees, Shrubs, and Evergreens

You will find trees, shrubs, and evergreens in sizes as small as #5 containers and as large as #25. Once you surpass a #25 Container size, shrubs and evergreens measure by height (in inches or feet), and trees measure in caliper.

Nursery Stock: Tree Caliper

Caliper is the measurement of the diameter of a tree trunk, in inches. These trees are planted as babies in farm fields and grown to more mature sizes. When they’re harvested, the root zone is wrapped in burlap, set in a wire cage to protect the root mass, and safely held together with twine – called balled & burlapped (B&B) plant stock. Johnson’s Nursery measures caliper 6” above the root flare. In our inventories, you’ll see 1.5” caliper (the smallest size we’re willing to sell a field-grown tree) and up. A homeowner is likely able to transport a smaller tree from 1.5” to 2.5” caliper without professional help. We recommend delivery beyond that size.

understanding nursery stock sizes field grown trees are measured by height

There are larger caliper trees in our inventory, such as 6.5” Caliper and even 8” Caliper (and beyond); however, they come with a price. For years, these larger trees occupy valuable space and resources and receive professional care. Larger trees have much larger root masses and are significantly heavier. They require larger machinery and more labor to harvest and transplant. To put this into perspective, the weight of a 1.5” caliper tree can be 250lbs; the weight of a 6.5” caliper tree can be between 2500-4500lbs – depending on the type of tree. Johnson’s Nursery often leads projects where 1 tree occupies an entire semi. Learn more about Specimen Trees & Evergreens >>

Nursery Stock: Heights

Shrubs and evergreens that are larger than a #25 container measure by height - inches or feet. These plants are field-grown, balled & burlapped stock, same as our discussion about trees and caliper size above.

understanding nursery stock sizes field grown shrubs conifers measured by height
understanding nursery stock sizes shrubs evergreens measured in height field plant harvest paul schwabe

The simplest way to understand the sizes of nursery stock is to understand where the plant was grown. Plants listed in container sizes are not raised in the ground; plants listed in caliper or height sizes are raised in the ground. And, again, it’s safe to equate a larger size with maturity, weight, and price. It usually comes down to the budget, so we do our best to stock a range of sizes to fit different budgets.

Why are larger plants more expensive? We encourage you to read our article on Tree Cycles to better understand how long plants take to grow from seed to salable.