QUESTION: How deep should the pots I use in a container garden be to grow healthy plants? Does it matter whether I’m planting flowers, herbs, fruit, or vegetables? — Becky K.
ANSWER: The pots in a container garden should be different sizes depending on which plants the containers will hold. We will list the best container sizes to use for many plants gardeners commonly grow. However, there are some guidelines you can use to determine the size your containers should be if your plant isn’t covered by our lists. You’ll find those at the end of this article.
Getting the right size of container for each plant you’ll grow is the first step toward a beautiful garden. The right container depth ensures your plants will have room for their root systems to spread out. If a plant’s container is too small, it may not be supported securely, which can lead to damage. Cramped containers also won’t hold as much water. Hanging baskets get more air circulation, making them especially prone to getting parched when the weather is hot. When a container is too large, it’s difficult for the soil to retain moisture. For all these reasons, you may notice wilting, stress, and poor health in plants that need to be relocated to containers of another size.
Don’t be confused by the fact that plant pots don’t have an industry sizing standard. You’ll find that some containers are measured in gallons while others are measured in inches. The measurements given in inches are telling you the diameter across the opening of the container at the top. You’ll see us discussing container size in volume, depth, and diameter across the top. We’ll be sure to specify which measurement we’re giving every time.
How Deep Should Containers Be for Flowers?
- Bachelor Buttons: 1-2 quarts
- Calendula: 1-2 quarts
- Dianthus/Pinks: 1-2 quarts
- Hyssop: Half gallon to 1 gallon
- Marigold: 1-2 quarts
- Nasturtium: 1-2 quarts
- Pansy: 1-2 quarts
How Deep Should Containers Be for Herbs?
- Basil: 8”-9” diameter—2 gallons
- Chicory: 18” diameter
- Chives: 4”-5” deep
- Cilantro/Coriander: 4”-5” deep
- Dill: 10”-12” deep
- Horseradish: 5 gallons or larger
- Lemongrass: 10”-12” deep
- Mint: 6”-7” deep
- Oregano: 1 gallon
- Parsley: 8”-9” diameter—2 gallons
- Rosemary: 8”-9” diameter—2 gallons
- Sage: 1 gallon
- Spearmint: 1-2 quarts
- Thyme: 6”-7” deep
How Deep Should Containers Be for Fruit and Vegetables?
- Arugula: Half gallon
- Asparagus: 2 gallons
- Beets: 10”-12” deep
- Bok Choy: 8” diameter
- Broccoli: 10”-12” deep—5 gallons
- Bush Beans: 6”-7” deep—2 gallons
- Cabbage: 5-15 gallons
- Cantaloupe: 5 gallons
- Carrots: 8”-9” deep—5 gallons
- Cauliflower: 3-5 gallons
- Celery: 2 gallons
- Chard: 8”-9” deep
- Collard Greens: 1-5 gallons
- Corn: 10”-12” deep
- Cucumber: 8”-9” deep
- Determinate Tomatoes: 16”-18” diameter or larger—10-15 gallons or more
- Eggplant: 8”-9” deep—2-5 gallons
- Endive: 18” diameter
- Fennel: 8”-9” deep
- Garlic: 6”-7” deep
- Green Beans: 12” diameter—5 gallons
- Green Onions: 1 gallon
- Indeterminate Tomatoes: 12” diameter or larger—5 gallons or more
- Jicama: 3 to 5 gallons
- Kale: 12” diameter—5 gallons
- Kohlrabi: 6”-7” deep
- Leeks: 8”-9” deep
- Lettuce: 4”-5” deep—8”-9” diameter—2 gallons
- Melons: 5-15 gallons
- Okra: 10”-12” deep
- Onions: 6”-7” deep
- Peas: 6”-7” deep
- Peppers: 8”-9” diameter—2 gallons
- Pole Beans: 8”-9” deep—5 gallons
- Potatoes: 10”-12” deep
- Pumpkin: 5 gallons
- Radicchio: 1 gallon
- Radishes: 8” deep
- Rhubarb: 10 gallons or larger
- Snow Peas: 2-5 gallons
- Sorrel: 12” diameter
- Spinach: 8”-9” diameter—2 gallons
- Summer Squash: 10”-12” deep
- Zucchini: 5 gallons
What Are the Guidelines for Plants Not Listed Above?
- Most vegetables require between six and 12 inches of container depth to grow healthy and strong.
- For flowering plants, avoiding pots six inches diameter or smaller in favor of those that hold a few gallons will help plants produce lots of beautiful blooms.
- Unless otherwise specified, a container at least eight inches deep will work for just about any herb plant.
- When in doubt, you can visually estimate the right container size for your plants. Look for containers about half as tall as the part of a plant you can see above the soil. If a plant measures 12 inches from the soil to its highest part, a six-inch container will work.
Regardless of what you’re growing and the size of the containers, you’ll need to make sure there are holes in the bottom for drainage. Despite the myths about pebbles or broken pottery to fix pots without drainage, they’re really inappropriate for gardening. Also make sure to leave one inch of empty space between the surface of the soil in each container and the top of the pot. That way there will be plenty of room for water to soak into the soil when you give the plants in your container gardening a deep watering.
Learn More About Container Gardening
https://ask2.extension.org/kb/faq.php?id=563361
https://www.bhg.com/gardening/container/basics/guide-to-plant-containers/
https://blog-yard-garden-news.extension.umn.edu/2019/05/become-smarter-gardener-in-2019-get.html
https://extension.uga.edu/publications/detail.html?number=C787&title=Gardening%20in%20Containers
https://www.gardeners.com/how-to/urban-gardening-with-vegetables/5491.html
https://www.goodhousekeeping.com/home/gardening/a20707074/container-gardening-tips/
http://greyduckgarlic.com/container-gardens.html
https://harvesttotable.com/pot-and-container-sizes-for-growing-vegetable-crops/
Some lines list only the volume in gallons and others the area by diameter not the depth. Useless information!
Agreed
Go to your local garden center armed with a tape measure, pen and pad. Then find the depths of each size plastic container, so if a plant is in a 2 gallon container and that container is 10 inches deep you can use that depth for a reference. 5 gallon containers are about 15 inches deep (the Lowes & Home Depot pails).
Very helpful information for me, but being a public school graduate and a stereotyped Marine Veteran; What do I know. Thanks for publishing; easy to figure out quantities.