Q: Can you give me any tips for growing veggies in large containers? What kind of soil is the best? Last year, I tried tomatoes in small containers with the low-moisture soil and they rotted. I plan to grow lettuce, tomatoes, cucumbers and peppers.
A: In order to successfully grow vegetables in containers, you must first choose those varieties suitable for container life. These varieties generally have a reduced growth habit and will not grow too large for a container. The seed packet information should say whether the variety is suitable for container gardening. Most varieties of peppers and tomatoes are suitable for containers. Suggested varieties for cucumbers include Salad Bush Hybrid, Bush Champion, Picklebush, Spacemaster, Hybrid Bush Crop and Midget Bush Pickler. For lettuce, try Black-seeded Simpson, Red Sails, Salad Bowl, Tom Thumb, Green Ice and Little Gem.
Pepper and tomato seeds can be started indoors mid-March to April, or purchase already started plants in May. Lettuce and cucumber seeds can be sown in mid-May directly into their containers, as they are more difficult to transplant. For a September harvest, plant cucumber seeds in early July.
Choose a standard type pot, the same height as diameter. Keep in mind, the bigger the better. Plant roots need plenty of room to grow. If you’ve done everything right and are disappointed with the results, the plant’s roots probably were restricted. For tomatoes, use a container at least 20- to 22-inches in diameter; peppers, 16-inch diameter; vining crops, 20 inch or larger container. Lettuce has shallow roots and will grow well in broader, flatter containers. Drainage holes are essential or the roots will rot.
To plant, cover the drainage holes with a paper coffee filter, some shards of clay or a fiberglass screen to prevent soil from washing out of the holes.
Container-grown plants require a loose, well-drained soil generous in organic matter. A good mix consists of one part each of potting soil, perlite, sphagnum peat moss and compost. Avoid using ordinary garden soil because it is probably infested with soil pests. The compost should be processed with temperatures high enough to kill pest organisms. Mix in a slow release fertilizer that provides additional nutrients slowly over a long period. Consider adding water-holding gels or hydrogels to the mix. The gels help to retain moisture in the soil until it is needed by the plant.
If your plant will need staking as it grows, place the stake in the pot before filling with soil and before you plant. Fill the container 3/4 full with the soil mix. Situate the plant close to the stake and fill in the soil mix around the plant. Water thoroughly. As the soil settles, add more soil until the container is filled to within 3/4 inch of the top. Tomatoes can be planted more deeply, covering about 1/3- to 1/2 of the existing stem to stimulate root development along the buried stem.
For direct-seeding cucumbers, fill the container close to the top and plant five to six seeds in the center of the pot, covering with 1/2 inch of soil mix. Add water and keep the soil warm. After germination, cut off the seedlings except for the two largest to avoid overcrowding. When they reach a height of 8 to 10 inches, cut off one, leaving only one plant per container. Do not pull out the seedlings, which can disrupt the root growth of the remaining seedlings.
Remember that vegetables grown in containers need at least eight hours of sunlight. Keep a careful eye on watering because the containers are above ground and dry out quickly. Sometimes twice daily watering is needed. If a plant is allowed to become too dry, the feeder roots are damaged.
By mid-July, begin to use a fertilizer solution for supplemental feeding. Once a week give each plant a good watering with a water-soluble fertilizer at the recommended rate. Water plants thoroughly first before adding fertilizer. Inspect daily for signs of insect and disease infestation. Do not allow vegetables to overly mature on the plant. Harvest them.
At season end, toss out the entire contents of each container; do not add it to the compost pile. Scrub each container and disinfect it with a 10 percent chlorine bleach solution before storing.
For more horticultural information, call the OSU Summit County Extension Hotline Tuesdays from 9 a.m. to noon at 330-928-4769, ext. 3, and request Fact Sheet HYG-1645-94, “Growing Cucumbers, Peppers, Squash And Tomatoes In Containers.”
Please note fact sheets are sent out free; there is a fee for bulletins. Many bulletins are available online at ohioline.osu.edu and can be printed from home or accessed at the public library.
Dayle Davis is a freelance writer and avid perennial gardener, with a B.A. in communications and course work in botany, geology and wildflowers. Davis is a Master Gardener emeritus under The Ohio State University’s Horticultural Extension. Readers can send in questions regarding lawn and garden issues, which could be featured in a future edition, as well as about the OSU Master Gardener program. Questions can be emailed to firstname.lastname@example.org, faxed to 330-665-9590 or sent to Leader Publications, 3075 Smith Road, Suite 204, Akron, OH 44333. Please do not send any leaves, seeds or other organic material. Inquiries about area garden clubs or groups should be sent directly to the particular organization in question.
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