Grow It Eat It: Maryland's Food Gardening Network

Planting and Caring for Your Container Vegetables

What can I grow?

Just about any vegetable or herb! Some of the more popular container crops are salad greens, peppers, eggplant, tomatoes, beans, chard, beets, radish, squash and cucumbers.
More challenging crops include melons, corn, potatoes, and sweet potatoes. The key is to experiment.
Look for “bush” or “dwarf” varieties of the crops you want to grow. There are quite a few tomato and cucumber varieties bred for small-space gardening.

How big a pot do I need?

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

Recommended media depth:
- 4-6 inches: salad greens, Asian greens, mustards, garlic, radish, basil, cilantro, thyme, mint, and marjoram. (Salad greens and some herbs have shallow, fibrous root systems and are well-suited to shallow containers with a large surface area).
- 8-12 inches: beans, beets, chard, carrots, chard, cabbage, pepper, eggplant, tomato, squash, rosemary, parsley, lavender, and fennel.
Required pot volume:
- 1-3 gallons: herbs, green onions, radishes, onion, chard, pepper, dwarf tomato or cucumber, basil.
- 4-5 gallons: full-size tomato, cucumber, eggplant, beans, peas, cabbage, and broccoli.

Planting Time

Don’t fill the bottom of the container with pebbles, gravel, or rocks unless you need the added weight to prevent tipping. Cover drainage holes with mesh, gravel, paper towel, or a coffee filter, to prevent soil from washing away.
Prior to planting, use a trowel or your hands to thoroughly work water into the growing medium. This is especially important for soil-less mixes containing peat moss.
Don’t cram media into container. Fill to within an inch or so of top of container. Follow seed packet directions for planting, spacing, and care.
For attractive and versatile containers, mix herbs and annual flowers in with the vegetable plants.
Herbs such as lavender, thyme, oregano, marjoram, and chives require a loose growing medium, and dry conditions. Plant them together in porous clay pots and add some sand to the mix.
Keep containers together to increase humidity and water retention

Keep those plants growing!

Three-season planting (a.k.a. “succession planting”): When spring lettuce or radish is spent, pull up and compost the plants. Then re-plant the container in late May with pepper plants, beans or cucumber seed. In early fall you can plant kale, lettuce or broccoli raab to finish out the season. Don’t forget to fertilize after each crop!
Give them support. Cucumbers, pole beans, peppers, tomatoes, and eggplant will all benefit from some type of vertical support.
Move plants around if containers are portable to maximize sunlight (for heat-loving crops) and shade (for summer-grown salad greens).

Trouble in Paradise: Diagnosing Plant Problems

Container-grown plants are subject to the same insect and disease problems as garden- grown plants, but container gardeners tend to have fewer problems. The biggest causes of plant problems are lack of water and nutrients, and overcrowding. Plants can also suffer root rot from too much water, especially if the growing mix does not drain well. Go to plantdiagnostics.umd.edu for additional help in diagnosing vegetable problems.

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For more information, contact Jon Traunfeld, University of Maryland Extension Specialist

Last updated: 01/9/2011