Garden Variety: How to grow vegetables, herbs in containers
Planting vegetables and herbs in containers is an easy way to start gardening on a small scale and is ideal for people who lack yards or whose yards are unfavorable for a traditional garden. A few crops can be planted now, and supplies can be gathered for later spring plantings.
Selecting a container
Container gardening requires containers, potting soil, seeds or plants, and a watering can or other access to water. Most of the things that can be grown in a traditional garden can be grown in a container if the size is right.
When selecting containers, bigger is better in most cases. Be creative — plants can be grown in nearly anything if conditions are otherwise right. In addition to traditional containers, consider gutters for shallow-rooted crops such as lettuce and spinach, old baskets or buckets, wooden boxes, or about anything that can hold potting soil. If the container does not have holes in the bottom, use a drill or a hammer and nail to make holes that allow water to drain.
Grow bags or fabric pots are an option that has gained popularity over the last decade. These pots are made of a heavy-duty felt-like fabric that provides excellent drainage. They are less prone to weather damage than ceramic, plastic and wooden pots. They can be reused for many years and can be left outside in winter with soil in them or emptied and stored flat.
For large plants such as tomatoes, plan on one plant per container. Smaller plants such as herbs may share large containers, but make sure they still have adequate room to grow rather than packing them in next to each other in a small pot.
Commercially available potting mixes are ideal over actual soil because they are formulated to provide an ideal growing environment for plant roots. Garden soil is heavier, may have layers of different soil types, and may keep plant roots overly wet or lacking oxygen.
Selecting a crop
Crops ideal for planting from seed right now are lettuce, spinach, radishes, carrots, green onions and Brussels sprouts. Buy transplants of broccoli, cauliflower and Swiss chard. Cabbage and kale may also be available as seeds or transplants and either can be planted right now.
Perennial and biennial herbs such as oregano, thyme, parsley, sage, chives, mint, rosemary and lavender can be planted now also. Buy transplants of these rather than starting from seed.
Warm-season crops that are ideal for containers are tomatoes, peppers, eggplant, beans, squash, cucumbers and basil. Wait to plant these until all chance of frost has passed. According to the
Kansas State University Weather Data Library, the average date of last frost for most of Douglas County is April 15-18. A late frost could still occur after that and will wipe these crops out. Also, the soil often remains too cold for tomatoes and similar crops until well into May.
Tomatoes, peppers, eggplant and basil are best to purchase as transplants. Beans, squash and cucumbers can be grown from seed.
With crops such as tomatoes and cucumbers, certain varieties are often labeled as being ideal for containers. These are usually short, bushy varieties. They are certainly more suitable for containers, but traditional varieties can still be done in containers if desired.
Potatoes are also great for containers. The ideal time to plant them in Kansas is mid-to-late March or in August for a fall crop.
Sweet potatoes can be grown in a very large container if desired. They are warm-season crops best planted in this area in mid-May to late June.
A few crops that are hard to grow in containers are corn (all varieties), melons and pumpkins. Corn needs to be planted in a patch to pollinate well. Poorly pollinated corn results in ears that fail to develop or fill out. Most melons and pumpkins produce large vines and require a substantial root space to support their top growth.
When planting, fill pots to within a quarter of an inch from the top. Tap the container lightly or water it to allow soil to settle, then add more to ensure it is full. This maximizes the space for roots to grow.
Plan to water as needed and always check for moisture below the soil surface prior to watering. This time of year, plants may survive on rainfall. In hot dry spells in a typical Kansas summer, containers may need to be watered every day.
Avoid putting gravel or any other materials in the bottom of the containers. This is an old practice that has been handed down but provides no benefit to the plant. The idea is that it improves drainage. One way to visualize how that does not work is to think of soil like a sponge. Laying a wet sponge on a bed of rocks does not help the sponge drain.
Another reason gardeners sometimes put rock or pieces of broken pottery in the bottom of a pot is to keep soil from washing out of the drain holes. Although a tiny bit of soil may fall out when it is first put in the pot, it will hold together with the rest of the soil as soon as it has moisture. Putting something over the hole reduces drainage and increase the chances of plants being overwatered.
— Jennifer Smith works in regulatory horticulture and has worked as a horticulturist for various government entities. She has experience in landscape design and maintenance and as an educator.