Updated: February 20, 2023

Containers can be temporary or permanent, practical or whimsical, artistic or utilitarian, expensive or free. When selecting containers, use your imagination and creativity, and know how much room your crops will need to grow to their full potential. You’ll also need to decide where and how to store the containers that are portable and used only during the growing season.

Choose the right container size

Match container size to plant size, both the top growth and root system. Don’t squeeze large plants into small containers. If you restrict root growth too much, your plants won't grow well. It’s useful to consider both the depth and total volume of your containers. 

  • For Large Vegetables-one plant per container.
    • Minimum 8-10 gallons of growing media, with a depth of 12-16 inches
    • Examples: tomatoes, pepper, eggplant, cucumber, Winter squash,
  • Medium Vegetables or Flowering Plants
    • Minimum 4-6  gallons of growing media with a depth of 8-12 inches
    • Examples: dwarf varieties (pepper, eggplant, tomato), summer squash, cole crops, beans, beets, chard, carrots, chard, cabbage, larger herbs (rosemary, parsley, lavender, and fennel), flowering and foliage perennials, ornamental grass
  • Small Vegetables or Flowering Plant
    • Minimum 1-3  gallons of growing media, depth of 4-6 inches
    • Examples: Herbs (garlic, basil, cilantro, thyme, mint, and marjoram), radish,  scallions, Swiss chard, spinach, salad greens, Asian greens, mustard greens, peas, beans, and small flowering annual
  •  Misc:
    • Potatoes: 30 gallons of potting mix
    • Strawberries: Depth of 8 inches
    • Dwarf fruit trees: 25-30 gallons of potting mix
    • Shrubs: 25 gallons of potting mix

Tips for choosing containers

  • Dozens of commercially produced containers can be purchased at garden centers and through mail-order catalogs.
  • Dozens more everyday objects can be recycled or transformed into suitable containers- 5 gallon-plastic buckets, truck tires, hypertufa troughs, wooden crates, ½ whiskey barrels, nursery pots,  kids’ wading pools, plastic trash bags, and plastic storage containers.
  • But, be aware that plastics not made for outdoor use can become brittle from exposure to the elements.
  • Except for the self-watering types, all containers should have holes or slits in the bottom to allow water to drain out.
  • Dark colors will create higher temperatures that could injure young tender roots and prevent the full development of a plant’s root system.
  • Containers made from porous materials (clay, ceramic, concrete, and wood) will dry out more quickly than containers made from plastic, or metal.

Container drainage

  • Whatever type of container is used, drainage is critical and may mean the success or failure of your garden and plants.  
  • All containers need to be able to allow extra water to drain out to keep plant roots from drowning and rotting. Drainage also allows excess fertilizer and salts to be washed out.  
  • If a container doesn’t have drainage holes consider double potting so that the plant can be removed to be water and then placed back once it has finished draining. After watering, don’t forget to empty saucers or any other container under the pot used to catch water.  
  • Most commercially sold garden pots will have drainage holes, but not all. Make sure to check before planting.
  • Additional drainage holes may be added depending on the material of the container.
  • To help with drainage, it is advisable to use potting feet or a brick to raise pots off the ground. 
  • Adding rocks, gravel, or broken pot shards in the bottom of a container will not improve drainage. It may raise the water table, which can lead to drainage issues. 

Still have a question? Contact us at Ask Extension.