The Deal with Nursery Pots

Nursery pots come in all sorts of shapes, sizes, colors, and thicknesses. It can be a bit overwhelming to try to become familiar with all of them, as each company in the industry sources their own unique plant containers. They are typically lightweight (to lessen shipping costs and make them easier to move), thin-walled, and black, though they can come in other colors as well, including green and orange. All have drainage holes towards the bottom. These pots are built to house the root systems of nursery-grown plants as they make their way from commercial growers to residential properties, and once plants are installed in the garden, they tend to sit unused, stacked in unsteady towers under potting benches or in toolsheds. This blog post is dedicated to these unsung heroes of the gardening industry.

Size Matters

When shopping for plants, it is necessary to have a basic understanding of pot sizes and the types of plants that are held in each. The smallest pots are those that typically hold small succulents or terrarium plants. These containers usually measure around 2 inches deep with a width of 2 inches. They are used to hold very small plants, and are outgrown quite quickly.

The smallest outdoor plants, typically annual flowers or edibles, can be packed into connected cells, typically in multiples of 4 or 6. These containers are used for plants that are installed en masse in borders and beds. They are made of thin plastic, and are easy to manipulate, making planting that much simpler. They are also perfect for home growers who start their own seeds indoors.​

A variety of standalone smaller pots are used for annuals and some perennials. These pots are great for herbs, edible plants, and smaller ornamentals. ​They are typically referred to as pint or quart-sized containers. They can be square or rounded, and are very popular for home growers who love to share their seedlings.

Larger pots than the ones listed above are typically measured in gallons, referring to the approximate volume of the container. Using 'gallon' as a moniker to measure containers is more a historical trend than an accurate measurement; in the past, growers used to cultivate their stock in actual leftover milk gallons. Nursery containers are rarely volumetrically equal to milk gallons nowadays. In these modern times, containers are numbered, and according to the ANSI American Nursery Stock Standard, have somewhat identifiable volumes. The chart below outlines this system:

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Container Size
#1
#2
#3
#5
#7
#10
#15
​#20

Minimum Volume
​0.7 Gallons
1.4 Gallons
2.7 Gallons
3.4 Gallons
5.8 Gallons
9.0 Gallons
12.0 Gallons
19.6 ​Gallons

Maximum Volume
​1.1 Gallons
2.1 Gallons
3.2 Gallons
5.4 Gallons
7.7 Gallons
11.5 Gallons
16.0 Gallons
22.3 ​Gallons

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The size of the pot will be listed somewhere on the plant's sale tag or sticker label, usually before the name of the plant. For example, the tag in the photo indicates that the New Mexican Privet it is attached to is planted in a #5 size pot (between 3.4 and 5.4 gallons). ​There are some nurseries that will use a pot's diameter to indicate the size of a plant, or simply to label empty decorative containers that are for sale. The chart below gives examples of these containers, along with their gallon equivalent and amount of soil they can be filled with.

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Pot Diameter
​4"

Gallon Equivalent
0.125

Suitable-Size Plants
Seedlings
​

Soil Needed
0.01 ft​³ / 0.137 lb.

5-6"

0.25

Small succulents or a single annual

0.03 ft​³ / 0.27 lb.

7-8"

1

Larger succulent, 2 annuals

0.13 ft³ / 1.1 lb.

10"

3

Small herbs, 3 annuals

0.40 ft³ / 3.3 lb.

12"

5

Luttuce, Spinach, Strawberries

0.66 ft³ / 5.5 lb.

14"

7

Larger herbs (Rosemary)

0.94 ft³ / 7.7 lb.

16"

10

Small shrubs or vines

1.33 ft³ / 11 lb.

18"

15

Tomatoes, annual displays

2.00 ft³ / 16.5 lb.

24"

25

Evergreen shrubs, dwarf trees

3.34 ft³ / 27.5 lb.

30"

30

Orchard fruit trees and larger plants

4.01 ft³ / 30 lb.

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The Big Empty

After plants have been brought home from the nursery, they should be removed from their containers. Although nursery pots are handy for growers and plant sellers, they are not always the best environments for strong root growth and overall plant health. When plants are left in their nursery pots for too long, they can become root-bound, the soil can get a little hydrophobic (meaning that it does not take in and hold water as it should), and pots can overheat, burning the roots growing inside. A good rule of thumb is to get plants into their forever homes ASAP after purchase to avoid stressing them out.

After containers are emptied, they can be cleaned of any remaining dirt or debris with a quick tap or rinse, and stored for future use. The best place to keep these containers is in the shade, in a space that is protected from harsh weather and being knocked around. Before reusing them, however, pots will need to be thoroughly cleaned to avoid transferring any pest or disease issues to other plants.

Reusing Pots

Nursery container pots can be reused for as long as they last. They are great for sharing propagations, starting seeds, and holding volunteer seedlings that don't have a set place in the garden yet. In order to avoid any ongoing issues with the reuse of plastic pots, including carry-over of pests and diseases, it is best to thoroughly clean and sanitize them. To clean your pots, follow the instructions below:

1. Remove any remaining dirt or dust with a dry brush or washrag.
2. Using dish detergent, fill a tub (or the kitchen sink) with warm, soapy water. Place the pots in the water individually (not stacked) and allow them to soak for about 10 minutes.
3. Rinse the pots with water, making sure to remove all soap residue.
4. Dawn protective wear, like gloves (and possibly safety goggles).
5. Fill a tub or bucket with a 9 parts water to 1 part bleach solution, making sure to be careful when pouring the bleach so it does not splash. This ratio adds up to 1 3/4 cups bleach added to a gallon of water. A 5-gallon bucket can be filled with 1/2 gallon of bleach and 4 1/2 gallons of water to get the same ratio.
6. Soak the cleaned, rinsed pots in the bleach solution for at least 10 minutes' time.
7. Rinse off the pots individually with water, scouring off any remaining mineral deposits with a sponge or rag..
8. Allow the pots to dry before stacking them, and then store them in a clean environment (off the ground) so they won't be re-contaminated.
9. Dispose of the bleach solution carefully (either down a drain or toilet). Do not pour out the bleach solution in any outdoor areas.

Tossing the Pots

Nursery pots are notorious for being a part of the waste footprint of the commercial plant growing industry. Approximately 350 million plastic nursery trays and pots are disposed of each year in the United States, and due to their chemical makeup, unfortunately many cannot be recycled. There are many small recycling or turn-in programs being run by various organizations across the U.S. with the goal of reducing this issue. It is best to do some independent research to find these organizations, as they are not always available everywhere, and depending on funding, can fade out of operation over time.

​Happy Gardening!

​- Kristi

Resources and References

How to Clean Plant Pots for Reuse (PDF)

Plastic Nursery Pots: Best Recycling Options

American Standard for Nursery Stock (PDF)