There’s no universally agreed upon unit of measurement for nursery stock. Caliper, container size, or height (inches or feet) are the common sizes for plants. In any of those 3 categories, it’s safe to equate a lower size with age, weight, and price. Not all sizes are available at any given time, but we do our best to continually stock a range of sizes. So, how do you make sense of all the options? Let’s start small and work our way up.
Growing trees in containers is very popular, 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.
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. Nor do all container manufacturers have a universal size requirement for the same size container, meaning the size of an empty #10 container may vary among manufacturers.
You will find perennials in sizes as small as Quart and as large as #5 containers. #1 containers is the most commonly size for perennials. You will find shrubs in sizes as small as #2 containers and as large as #15 containers. Perennials are not available in sizes other than containers.
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.
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 and 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.
There are larger caliper trees in our inventory, such as 6.5” Caliper and even 8” Caliper (and beyond), but 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 has been involved in projects where 1 tree occupies an entire semi.
Shrubs and evergreens that are larger than a #25 container measure by height - inches or feet. These plants are field-grown, balled & burlapped stock, as we discussed with trees and caliper size.
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.