How to avoid common problems growing vegetables in containers

Sometimes you just don’t have the resources to grow vegetables in a traditional garden. A lack of time or space or poor soil conditions can make container gardening a more realistic option. And there are some benefits to container gardening — you can control the soil conditions, the sun exposure and watering regimen completely.

On the other hand, there are common pitfalls gardeners encounter when using containers to grow vegetables. Learn more about common container gardening mistakes and try to avoid them this summer.

Common Problems

1. Choose the right size containers for the right plants. The biggest problem encountered by beginning gardeners trying to produce vegetables in containers is choosing containers that are too small for a mature plant, which leads to stunted growth and a lack of fruit production. Use these guidelines from Texas A&M Agrilife Extension to choose the right size containers for your vegetable plants — *Name (Container Size, Number of Plants) – Varieties:
   • Broccoli (2 gallons, 1 plant) – Packman, Bonanza, others
   • Carrot (1 gallon, 2-3 plants. Use pots 2 inch deeper than the carrot length) – Scarlet Nantes, Gold Nugget, Little Finger, Baby Spike, Thumbelina
   • Cucumber (1 gallon, 1 plant) – Burpless, Liberty, Early Pik, Crispy, Salty
   • Eggplant (5 gallons, 1 plant) – Florida Market, Black Beauty, Long Tom
   • Green Bean (2 gallons minimum, space plants 3 inches apart) – Topcrop, Greencrop, Contender, (Pole) Blue Lake, Kentucky Wonder
   • Green Onion (1gallon, 3-5 plants) – Beltsville Bunching, Crysal Wax, Evergreen Bunching
   • Leaf Lettuce (1 gallon, 2 plants) – Buttercrunch, Salad Bowl, Romaine, Dark Green Boston, Ruby, Bibb
   • Parsley (1gallon, 3 plants) – Evergreen, Moss Curled
   • Pepper (5 gallons, 1-2 plants) – Yolo Wonder, Keystone Resistant Giant, Canape, Red Cherry (Hot), Jalapeno
   • Radish (1 gallon, 3 plants) – Cherry Belle, Scarlet Globe, (White) Icicle
   • Spinach (1 gallon, 2 plants) – Any cultivar
   • Squash (5 gallons, 1 plant) – Dixie, Gold Neck, Early Prolific Straightneck, Zucco (Green), Diplomat, Senator
   • Tomato (5 gallons, 1 plant) – Patio, Pixie, Tiny Tim, Saladette, Toy Boy, Spring Giant, Tumbling Tom, Small Fry
   • Turnip (2 gallons, 2 plants) – Any cultivar
2. Choose the right type of container. There are pros and cons to every type of container, but some work better than others for vegetable gardening and some shouldn’t be used at all. Terra cotta pots are a favorite, but it should be noted the soil will dry out more quickly and you’ll have to water more frequently to keep your plants adequately watered. Plastic pots retain water much better; however, are not very forgiving when plants are overwatered. Any plastic container used in a container garden should have drainage holes. If they’re not already there, drill some. Containers that contain led or other toxic materials should be avoided as these materials can leach into the soil and into your food. Additionally, black and metal containers should be avoided because they retain heat and can cook the roots of your plants in the sun.
3. Water your plants frequently. Plants in containers dry out much more quickly than those in traditional gardens because there’s not as much soil to retain moisture. When it is hot and dry in the middle of the summer, inconsistent watering can cause your plants to wilt and die or cause other problems like blossom-end rot due to insufficient nutrient uptake. You may even have to water them in the morning and evening to ensure they are receiving enough water.
4. Don’t water too much. Watering too much can cause root rot and kill your entire plant. If the leaves on your plants start turning yellow, their roots are too wet and soggy. Find more tips on the water requirements of individual plants by reading How to water your vegetable garden.
5. Optimize the soil. There are a couple of things to consider when choosing soil. First, you want to consider what your goal is — fruit production. Many potting soils contain a lot of nitrogen and encourage stem and leaf production. The appropriate soil for vegetable plants will contain a better balance of nutrients to encourage fruit production. Choose a soil meant for vegetable gardening or vegetable gardening in raised beds. The second consideration is the consistency of the soil. You won’t have to worry about this as much if you are purchasing soil, rather than using soil from your yard. Heavy clay soils do not drain easily and can cause problems with water retention. If you are planning to mix your own soil make sure to add plenty of compost and some fertilizer to ensure good drainage and get your plants off to a healthy start.
6. Fertilize regularly. As mentioned above, too much nitrogen can actually hinder fruit production because it encourages growth in other areas of the plant. Choose a fertilizer that contains more phosphorus and less nitrogen to help encourage fruit production. Additionally, make sure you fertilize your plants regularly as container plants can use up the nutrients in their potting soil regularly. Apply liquid fertilizer twice a month.
7. Select plants that grow well in the available sunlight. If you’re limited to growing vegetables in an apartment, balcony, patio or outdoor space with fewer hours of sunlight, choose plants that grow well in those conditions — leafy greens and many herbs prefer partial shade. Likewise, if you have a sunny space, choose plants that prefer full sun — tomatoes, squash and cucumbers enjoy full sun.

Resources

• Texas A&M Agrilife Extension
• The University of Maine Cooperative Extension