Container gardens: A unique horticultural alternative

By: Sarah Wojcik | C&G Newspapers | Published April 8, 2015

METRO DETROIT — For people with space challenges and unfavorable soil conditions, container gardens may be a simple, colorful solution.

Mary Gerstenberger, Macomb County Michigan State University Extension consumer horticulture coordinator, and Karen McCuen, president of the Shelby Gardeners Club, agree that whether people are planting vegetables or flowers, the first step is to select the right container.

Gerstenberger recommends using a glazed or plastic pot to keep in moisture, as water can seep through untreated clay pots. Choosing the right size container is also important. When purchasing seeds, Gerstenberger said, people should consider how deep the roots need to grow and pot appropriately.

“Radishes, lettuce and spinach have shallower roots and are more appropriate for a window box-sized container several inches deep,” she said. “Tomato plants have deep roots, so a larger pot is good for growth.”

Beans and peas can also be grown in pots, as long as they have a support structure and the pot is the appropriate depth for the type of bean or pea plant, she said.

For blueberry bushes, Gerstenberger recommends planting them in a large container. The bush requires soil with a very low pH, and she said it is difficult to achieve such soil conditions in the ground, so growing blueberries in a container is a better bet.

On seed packet labels, people should look for vegetables listed as “compact dwarf,” or suitable for pots and containers.

McCuen and Gerstenberger agree that only potting soil should be used for container gardens.

“Don’t use regular garden soil,” McCuen said. “Potting soil is specially formatted with fertilizer already in it, and the products in it are light, so it won’t compact down like garden soil. It also has good drainage so plants don’t drown.”

McCuen said people should make sure that containers have drainage holes. She recommends placing a coffee filter in the bottom of the pot to prevent soil from washing out onto a patio or driveway, and placing a layer of rocks or a piece of broken pottery at the bottom of the pot to help with drainage and moisture maintenance.

For containers on wooden decks or balconies, Gerstenberger recommends placing a catch basin, such as a saucer, beneath them to collect water in order to prevent staining of the wood.

When selecting what to plant, the experts agree that it is important to make selections based on how much sunlight is available in a particular setting. Most vegetables require eight to 10 hours of sunlight a day, although lettuce, spinach and radishes are cool weather plants that require a minimum of six hours of sunlight, Gerstenberger said.

For heavy pots, she recommends planning ahead and having something with wheels to transport the pot, for example, from one side of a deck to the other to absorb the most sunlight.

When planting flower container gardens, McCuen said a common practice is the “thriller, filler, spiller” technique.

“Thrillers are your focal point. They’re normally your tallest plant, such as angelonia or Mexican sunflower,” she said. “Filler plants go around the thriller, like petunias and geraniums.”

She said perennials can also work as fillers, including coral bells, which come in many new varieties and colors this year.

“Then you need spillers to hang over the edges of the pot and hang down — plants like vinca vines, Swedish ivy and sweet potato vines,” McCuen said.

Most potted flowers, she said, need to be watered daily and fertilized approximately once a month.

Gerstenberger said vegetable container gardens can also follow the “thriller, filler, spiller” technique with tomato plants, lettuce and peas. She said the tomato plants will shelter the lettuce, which needs less sunlight and also comes in many varieties, from light green to burgundy, from frilly to coiled.

She recommends avoiding watering the leaves on vegetable plants, as they could grow fungus.

For those not blessed with a green thumb, McCuen recommends potting succulents, which are similar to cacti and come in a myriad of varieties. Add in a small house, a pebble path and a few fairies, and you’ve got a fairy garden.

“Use potting soil, have good drainage, place the right plant in the right place and water them, and you’ll have a great pot,” she said.

For more information about container gardens and other types of gardening techniques, visit or call the Macomb County MSU Extension hotline at (586) 469-5180.