UCANR

Growing Vegetables in Containers

  • May 12, 2026
  • By CoCoMG Helpdesk

Soil Depth Needed for Vegetable Varieties

  • 9 to 12 inches for shallow rooted vegetables: lettuces, radishes, green onions, spinach, chard, kale, herbs
  • 12 to 14 inches for moderate depth vegetables: peas, carrots (short varieties), eggplant, peppers
  • 16 to 18 inches for tomatoes, potatoes, zucchini, winter squashes, beans, cucumbers

Soil for Containers

  • Make your own container mix by combining equal parts of compost, coconut coir and vermiculite or perlite. Coir is sold in a compressed form and will expand in volume when soaked in water. Soak it before combining with the other ingredients. Many sources suggest the use of peat moss rather than
    coir. Peat moss is harvested from wetland peat bogs. Because it takes thousands of years to regenerate peat, environmentalists consider peat moss to be a nonrenewable resource. Coir is a byproduct of the coconut industry, and is renewable.
  • If you are re-using potting mix, you may want to add some organic fertilizer to the soil mix (e.g., bone meal for potassium and blood meal for nitrogen). Use about one cup of fertilizer per 5 gallons of soil mix. You can add loamy garden soil to your mix, but before you add soil, heat the soil in an oven for 1 hour at 210°F to kill any bacteria, fungi, insects, or weed seeds.
  • Or purchase a good potting mix from a garden center.

How to Make and Use Worm-Cast Tea

  • Start with 2-3 cups of worm castings. If you don’t have a worm composter, you can buy worm castings in many nurseries or at Our Garden.
  • Mix worm castings with water in a five-gallon bucket. Add a tablespoon of molasses to feed the micro-organisms in the worm castings (optional). Stir well. Also stir the mixture a couple of times a day.
  • After 24 hours (and not more than 48 hours), dilute the mixture you have created. Add one part of the mixture to 4 parts of water. (Your 5 gallons of mixture will make about 25 gallons of diluted mixture. If you need less, start with less than 5 gallons.)
  • Water your container plants (indoor and outdoor) with the mixture.
  • Your container plants should be watered with this mixture every two or three weeks.
  • Can also be used to water plants that are growing in the ground.

Tomato Varieties Suitable for 5-Gallon Containers

  • Dwarfs: Patio, Pixie, Tiny Tim, Saladette, Toy Boy, Spring Giant, Tumbling Tom, Small Fry, Red Robin, Sugar Sweetie, Tiny Tim
  • Determinate varieties: Black Sea Man
  • Semi-determinate varieties: Lizzano

Ways to Conserve Water When Growing Crops in Containers

  • Use plenty of compost and coconut coir in soil mix.
  • Choose the right type of container.
  • Use non-porous containers (e.g. fiberglass, plastic or glazed pottery); avoid terra cotta.
  • Large containers dry out more slowly than small containers.
  • Light colors are less hot than dark colors.
  • Use a self-watering insert to catch draining water.
  • Save household waste water to use for watering containers. For example, catch water in bucket while shower water is heating up.
  • Use 3-4 inches of organic mulch around plants.
  • Straw or hay [beware of weed seed]
  • Shredded leaves or fine bark
  • Can also mulch with grass clippings if you start with a thin layer (1/2inch) and allow layer to dry thoroughly before adding another layer. Start with a layer of newspaper below clippings.

Some Online Resources for Further Information

UC Master Gardener Program of Contra Costa County
2380 Bisso Lane, Concord, CA  94520

Website: https://ucanr.edu/site/uc-master-gardener-program-contra-costa-county 

Source URL: https://ucanr.edu/site/uc-master-gardener-program-contra-costa-county/article/growing-vegetables-containers