Q: What advice can you give me about growing vegetables in containers?
Answer: Edibles can be grown successfully in containers when you follow a few guidelines for selecting the right containers, planting media, and plant combinations:
- Containers: The container needs to be large enough to hold the roots of the plants when they are mature so read the plant label and make sure the container fits the plant. Make sure the container you use has a drainage hole in the bottom. A small rock on the hole will keep the pot draining. There are all types, shapes and sizes available in clay, cement, metal, wood and plastic resin. The new plastic resin is more lightweight and retains moisture well. They can be left outside all year without fear of cracking.
- Design: Put plants in the same container with similar requirements for light, water, and nutrients. Summer vegetables require 6-10 hours of full sun for optimum production and will require daily watering that is even and consistent.
- Planting Medium: Never use garden soil in a container because it will compact, restrict root growth, and not drain well. A better plan is to use a good quality soil-less potting mix which has been pH adjusted. Look for planting media certified by the Mulch and Soil Council, the national nonprofit trade association for all producers of horticultural mulches, consumer potting soils, and commercial growing media. Certification ensures that the product label accurately identifies what is in the bag. If you want to make a homemade potting soil, use one part finished compost, one-part perlite, vermiculite or coarse builder’s sand, and one-part pasteurized soil or potting soil. Container soils are best changed every 2 years.
- Planting: Always start out with a clean container. Wash a used pot with a 10% bleach solution and rinse it out. Moisten the potting medium before planting. Position the plants in the container at the same depth they were in the original container. Make sure you have a minimum of 3 inches of soil beneath the root ball for additional root growth. An inch or so from the top of the container is needed for watering space.
- Watering and Fertilizing: Watering requirements will be determined by the weather, size of pot, type of pot, and location of your container. The plant species should also be a main consideration when watering. Check the container daily and even twice per day on hot windy days. A good test is to stick your finger in the soil medium and only water if it feels dry. Water the container until the excess water runs out of the hole in the bottom of the container. If the soil has dried out so much that it is receding from the sides of the pot you must rehydrate the soil by submerging the pot in water until the soil stops bubbling or if too large water several times until the soil is holding water again. Always dump out any water left over in a saucer to avoid soluble salt build up. Frequent watering flushes out a lot of the nutrients you provide. A regular fertilization schedule should be followed to keep the plants healthy and actively growing. For light feeders such as potatoes, radish, and spinach fertilize at planting. For medium feeders like beans, beets, carrots, kale, lettuce, and peppers fertilizer every 12 weeks with a timed-release fertilizer. For heavy feeders like cucumbers, eggplant, squash, and tomatoes fertilize every two weeks with a liquid fertilizer or every 8-10 weeks with a timed-release fertilizer.
- Maintenance: During the growing season of the container it will be important to check regularly for disease and insect problems. Cut out any dead or damaged plant parts and remove disease parts or plants. Remove insects by hand picking.
- Harvest: Pick produce as it ripens. Avoid leaving overripe produce on plants.
A useful Extension publication with suggested designs is available at https://content.ces.ncsu.edu. Search for “how to create a container garden.”
Mary Jac Brennan is the agent for fruit and vegetable horticulture for small farms and local food for the Forsyth Cooperative Extension. Contact Mary Jac about commercial production, local foods, and sustainable agriculture questions. For information on home and gardening issues, contact the Forsyth Cooperative Extension office at firstname.lastname@example.org or call 336-703-2850.