What’s the Difference Between #1, #2, #3, #5, #7 Container Sizes?
What’s the Difference Between #1, #2, #3, #5, #7 Container Sizes?
We get a lot of questions about what the different container sizes really mean for your landscape. On every product page, you’ll see a tabbed navigation under the photos. This navigation will give you a lot more detail about the plant you are considering.
You’ll also see a Plant Sizes tab with a helpful comparison video. Now, read on for a behind the scenes look at the trade secrets of the nursery industry.
Too long, didn’t read? Just know that in general, container size is relative to the age of the plant with a few notable exceptions such as miniaturized Bonsai trees, or the galloping growth of Willow Hybrid trees.
The older the plant, the more developed the root system. That’s what make a BIG difference in your landscape. Buy the biggest plant you can for immediate impact in your landscape.
Selecting the Best Container to Support Root Production
Our nursery production has changed over the years. Every industry is pushing innovation, and the nursery trade is no different. As more plants are being grown in pots, production innovations were being trialed.
At Nature Hills, making new roots that are healthy and branch well is our goal.
Nurseries and growers are always looking for new products that will make the best roots for their plants right from the start.
New container options were offered with improved designs with slits or ridges that might assist the plants in producing a better root system. The shape and size of the pots we use have changed due to ongoing research.
In addition, our nursery plant containers must be strong, flexible, label compatible and cost-effective. We protect our plants very well for shipping.
Market Evolution of Nursery Plant Container Production
Keep in mind that most container grown plants used to be grown in quart pots, 1 gallon, 2 gallon, 3 gallon, 5 gallon, and 7 gallon sizes.
However, with competition comes changes. More sizes and styles of plastic containers began to be offered by the container companies, which were soon patented.
Now, companies produce pots that span a range of volumes and have moved away from true gallon sizes to better suit the root production needs of specific plant genus and species.
Most nurseries then began labeling them by broad ranges, including #1, #2, #3, #5, #7 to communicate or help buyers visualize the size of plant being sold across this range of volumes by class.
Nitty Gritty on the NCWM Weights and Measures Law
With that change, consumers began to question the sizes of the containers. Plants might be listed as a 3 gallon plant but the volume of soil in these pots was not consistent.
The NCWM Uniform Weights and Measures Law was enacted to help eliminate some of these inconsistencies in container size across the industry. They were looking for uniform packaging and regulation on labeling. This law was put into place to bring some continuity to the industry.
The reason for this law is to help the consumer in comparing similar products by using uniform and consistent quantity information on the product package, or in advertising and signage. The regulation forces the container producers to list their volume in both U.S. and metric measures, the contents, and either the common or botanical names or both.
New signage and labeling practices in the nursery industry affected the business all along the supply chain – from container producers, growers, label manufacturers to plant branding firms and eventually the retailers. Now, within a compliant industry player, every potted plant you buy will have the volume of soil in that pot listed somewhere on it or it will be readily available from the grower.
So, How Big is the Plant Grown in These Different Containers?
So now you know about containers. But you still don’t know the actual size of the plant growing in the pot! Well, that’s a little bit harder to answer. Read on with us for the rest of the story.
Life Cycle of a Container Grown Perennial
As a nursery and grower, we know the many things that can affect the physical size of each plant that we offer. Some of the size differences are based upon the time of the year, pruning methods and timing, or variances from grower to grower or to different regions.
- Think about shipping a dormant Bleeding Heart perennial in a #1 container in a March shipment. That plant would not even be showing any growth above ground yet, but it would just be a pot full of soil and roots.
- Now ship that plant in May and it might be 18” tall and flowering.
- What about shipping a Bleeding Heart perennial in a #1 container in October? It may have gone dormant again and appear to be nothing more than a pot filled with soil and roots.
In all three shipments the size of the pot, and the volume of soil in it was exactly the same, but the size of the plant varied depending upon the time of year it was shipped. The weights and measures labeling is in place as a #1 pot, but the plant size is not consistent.
Pot Size Equals the Age of The Plant
The pot size dictates the volume of soil mix that was used to grow that plant.
When a grower is producing a new plant in a container, the size of the root system and age of the plant has to be matched to the container size that is being used to grow that plant.
Container size has more to do with the age of the plant, than the physical size of the plant growing in that pot.
Best Growth is Achieved in the Right Sized Container
In many cases, if a small plant is placed in a pot that is too large for it, the growth is negatively affected. If there is too much soil in the pot, it may not dry out quickly enough for the plant to use the water as it is needed. That excess water can cause the roots to rot, and the plant to die.
Conversely, in a pot too small, the roots become overcrowded. If roots are crowded, the soil may dry out too quickly. The plant may stress because the moisture is used up before receiving additional water.
At our nurseries, our production personnel are matching the age and size of the plants to the size of the container they are being grown in. The size of the pot is in correlation to the age of the plant. Do keep in mind the example of the Bleeding Heart perennial shipment, and how timing can affect what you see at delivery.
Our production facilities shift these plants to larger pots as needed. Nature Hills has a phenomenal group of growers that ensure we remain compliant with our labeling on container sizes and correct plant nomenclature. However, our concern goes deeper than mere compliance as we continue to grow and expand shipping across the entire country.
Plant Sentry™ Keeps Nature Hills Compliant
Nature Hills is the leader in supplying healthy plants across the country to your doorstep, while remaining compliant for all state and local regulations. Why do we lead all other online plant suppliers in all categories? It is due to our commitment to excellence and dedication to plant health until it arrives safely to your home.
We use an online service called Plant Sentry™ which only allows for the purchase of the correct legal size plant, depending on where it originates from. This is important to ensure that the plant leaves from the best healthy growing environment. The program also insures that each plant is labeled entirely correctly as guided by legal weights and measures, so you know that you are getting exactly what you paid for.
Nature Hills has prepared a recent video that explains the plant age and the size of the pots they are being grown in. This should give you a better idea of the amount of work that we have into a plant.
Unsure about just how big your ordered plant is going to be? Our horticulturist explains simply how plant sizes are categorized in this article. Read it here!
Container and Pot Sizes: How Much Soil Do I Need?
Container and growing pots come in a variety of sizes. In the United States nursery and garden centers sell pots by the size in inches and gallons. In the United Kingdom, Europe, and most of the rest of the world containers are sold by the size in centimeters and liters.
There are few standards when it comes to container sizes and volumes. To determine the size of a pot measure across the top from one side to the other to determine how many inches or centimeters it is. However, because some pots are long and others are squat and because the sides of some pots are straight and others are tapered, the volume can vary.
How Much Soil Does a Container Need
When it comes to filling a pot with soil estimating how much soil you need is an approximation. Often the volume of a container is measured in liquid quarts or liters, but, of course, when you purchase soil you are purchasing dry (potting soil is not liquid). A dry quart is equal to about 1⅛ liquid quarts. When deciding how much soil to purchase it’s best to factor soil compression that commonly results from moistening and pressing the soil into the pot. Soil compression can add another 15 to 20 percent dry soil to the container. Also take into consideration that when you transplant a plant from one container to another, you will be moving some soil around the roots of the plant.
Take notes on the pots you have and the soil they require. In short order, you will have a realistic estimate of how much soil you will need to purchase when potting plants.
Container garden on a balcony
Soil for Standard Clay Pots and Plastic Nursery Pots:
This chart will help you translate container sizes for standard clay pots and black nursery pots and give you an approximation of how much soil each will require (again these are dry soil measures):
4 inch pot (10 cm) = 1 pint (0.5L)
5-6 inch pot (13-15 cm) = 1 quart (1L) = 0.03 cu. ft.
7-8 inch pot (18-20 cm) = 1 gallon (4L) = 0.15 cu. ft.
8.5 inch pot (22 cm) = 2 gallon (7.5L) = 0.3 cu. ft.
10 inch pot (25 cm) = 3 gallon (11L) = 0.46 cu. ft.
12 inch pot (30 cm) = 5 gallon (19L) = 0.77 cu. ft.
14 inch pot (36 cm) = 7 gallon (26L) = 1 cu. ft.
16 inch pot (41 cm) = 10 gallon (38L) = 1.5 cu. ft.
18 inch pot (46 cm) = 15 gallon (57L) = 2.3 cu. ft.
24 inch pot (61 cm) = 25 gallon (95L) = 3.8 cu. ft.
30 inch pot (76 cm) = 30 gallon (114L) = 4.6 cu. ft.
Soil for Hanging Baskets
10 inch (25 cm) = 5.5 dry quarts (6L) = 0.21 cu. ft.
12 inch (30 cm) = 7.9 dry quarts (8.4L) = 0.3 cu. ft.
14 inch (36 cm) = 13.9 dry quarts (15.3L) = 0.5 cu. ft.
Soil for Plant Bowls
8 inch (20 cm) = 1.9 dry quarts (2L) = 0.07 cu. ft.
10 inch (25 cm) = 3.7 dry quarts (4L) = 0.14 cu. ft.
12 inch (30 cm) = 5.5 dry quarts (6L) = 0.21 cu. ft.
14 inch (36 cm) = 8.4 dry quarts (9.2L) = 0.29 cu. ft.
16 inch (41 cm) = 12.0 dry quarts (13.2L) = 0.46 cu. ft.
18 inch (46 cm) = 18.8 dry quarts (20.7L) = 0.73 cu. ft.
21¾ inch (55 cm) = 31.2 dry quarts (34.3L) = 1.21 cu. ft.
Soil for Oval Planters:
12 inch (30 cm) = 3.8 dry quarts (4.1L) =0.14 cu. ft.
16 inch (41 cm) = 7.3 dry quarts (8L) = 0.28 cu. ft.
20 inch (51 cm) = 9.4 dry quarts (10.3L) = 0.36 cu. ft.
Soil for Square Planters:
12 inch (30 cm) = 11.2 dry quarts (12.3L) = 0.48 cu. ft.
15 inch (38 cm) = 23.0 dry quarts (25.3L) = 0.89 cu. ft.
Soil for Window Boxes:
24 inch (61 cm) = 11.7 dry quarts (12.8L) = 0.45 cu. ft.
30 inch (76 cm) = 15.6 dry quarts (17.1L) = 0.6 cu. ft.
36 inch (91 cm) = 19.7 dry quarts (21.6L) = 0.76 cu. ft.
Soil for Strawberry Pots:
5 gallon = 14 dry quarts (15.4L) = 0.54 cu. ft.
Also of interest:
Hi this is Maniraj a research scholar from India I would like to know how to calculate volume of a pot and also what does it mean by 1litre of soil.
A litre of soil is the amount of soil that will fill a litre container which is 10cm x 10cm x 10cm.
Volume of a pot… I have a 9 inch diameter pot in front of me as an example… 9 inch top diameter and 7 inch bottom diameter= average diameter of 8 inches.. Formula is.. “Pi” multiplied by “R squared” Radius squared, then multiply that product by the height… So in my case with a nine inch pot I have Pi (3.14159) times (4×4) or 3.14159 X 16= 50.25 square inches multiplied by 8 inches height equals 402 cubic inches. If you want cubic feet then divide the 402 cubic inches by 1,728 cubic inches per cubic foot and you get .237 cubic feet. The 8 1/2 inch container is listed as being .3 cubic feet; the actual measurement would be about .2 cubic feet.
what is the density of potting soil?
Soil density can be measured in a few ways. The presence of sand, silt, loam and organic matter can vary from one soil sample to another–whether you are measuring garden soil or potting soil. Sometimes soil density may include the effect of moisture on the soil. For gardeners, the most common way to measure soil density (garden soil or potting soil) is the hand test: simply grab a handful of soil and squeeze it into a ball. If the soil crumbles apart into many pieces and will not reform when you squeeze it again, then the soil is uncompacted and dry; this soil might be termed light or friable. Soil that breaks apart into a few large chunks that easily reform when you squeeze them is a sign of uncompacted soil with a good amount of moisture. Compacted soils will not break apart in your hand, but are malleable and plastic-like in their consistency when moist; then are hard and unbreakable by hand when dry; this soil would be termed heavy or dense. Other ways to measure soil density include the Protor test; this test requires that three different layers of soil are placed into a cylindrical tube in sequence. A standardized weight is dropped onto the soil repeatedly and the results are measured. The sample then dries overnight and is weighed in order to measure the moisture content. The Nuclear Density Gauge Test is done with a small device that can be transported between testing sights. It operates by measuring the occurrence of a radioactive isotope in the soil in one of two ways. Either by generating small doses of gamma rays that hit the soil surface and then measuring the backscatter–reflection–of the radiation, or by inserting a probe into the soil which transmits the gamma rays directly. Dense, compacted soils absorb more radiation than uncompacted soils. Nuclear density gauges are an expensive, but accurate, timely and effective means of measuring soil compaction.
With 5kgs of potting mix soil, how many medium sized small sized pots can be filled?
Container and growing pots come in a variety of sizes. In the United States nursery and garden centers sell pots by the size in inches and gallons. In the