Lisa Kortan puts a lot of thought into the color and texture of annuals in containers and beds around Yankton each season. But she additionally requires that annuals make her work easier. Anyone getting ready to plant annuals in containers or beds might be interested in her choices and how she cares for them to get the results.

Kortan, urban forester for the City of Yankton, especially enjoys the horticulture part of her position. It’s her seventh season to provide colorful flowers for Yankton. She gets ideas from plant websites and area greenhouses and compares notes with other park professionals. She likes plants with pizazz for the high-visibility spots like downtown Meridian District, Riverside Park amphitheater, Douglas Avenue boulevard, pool area at Memorial Park and Westside Park gazebo. Plants in her care mostly grow in sunny, wind-exposed clay loam or sandy flowerbeds or pots watered daily in summer. Annuals in her care need to peak soon after Memorial Day and remain beautiful until first frost, often in early October.

Growing Conditions

Before color and texture, she looks for annuals that can withstand erratic temperature variations of this region from late spring to fall. They have to be hardy plants that can withstand wear, wind and are drought and heat tolerant. Tolerance to variable kinds and conditions of soils is a must.

“I look for plants that don’t have to be dead-headed, called re-bloomers. We don’t have a lot of time to take care of plants beyond watering, fertilizing and a little weeding,” Kortan said. “I look for plants that can make it a day (in summer heat) without watering and then come back.”

Annuals in the hayracks on streetlights in the Meridian District have the additional constraint of small space for soil in the 24-inch coconut liner baskets. Smaller soil containers are more impacted by summer heat than larger containers. Soil temperatures may spike on hot days, so these basket plants are required to tolerate the heat on roots.

Soil and Care Methods Make a Difference

Hayracks on downtown streetlights are above eye level and showy. The coconut liners are partly chosen for their natural appearance. Soil for hayracks has characteristics like soil in the average hanging basket with a coconut liner. Kortan recycles liners for three years but replaces soil every year. She only uses ProMix + BX potting soil which contains a fungicide for these hayracks. She gets bales of the soil from The Tessman Company, a wholesale supplier in Tea, South Dakota.

“It has to do with how wet we have to keep the soil in the hayracks. We water them four or five months,” she said.

For large planters and flowerbeds around town, Kortan uses her own soil mixture of potting mix and topsoil and a little city compost. She adds more soil mixture to containers and amends the bed soil. The work crew overturns soil and adds more mixture with shovels. She goes by color and feel of the mix and wants it to form a loose dark ball. The compost is a soil additive that supplies nitrogen in the form ready for plant use. She never uses compost by itself because it inhibits seed germination and dries out quickly. A little compost is added to topsoil in order to improve soil tilth.

“For a soil mixture, I don’t want plant roots to be water-logged,” she said. “It’s better if soil dries out (between the waterings).” That helps prevent disease. She wants a soil mixture that is airy and dries out before it is watered again.

Crews water hayracks and planters daily beginning Memorial Day. If the temperature is 95 degrees F. or higher in summer, they water twice.

“People always ask about flowers in the hayracks downtown that look so good. To me, it’s the fertilizer and the water. My first few years, I fertilized only once a week with liquid fertilizer. My contact from Tessman said his grower suggested two or three times a week. I also get tips from park colleagues in Canton, Brookings, Mitchell and Pierre.” Now she applies special petunia fertilizer three times a week. It is 20 (Nitrogen)- 3 (Phosphorus)-9 (Potassium). “Without the petunia fertilizer, the petunias tend to turn yellow when they are watered so much.”

Large pots, flowerbeds and other plants are fertilized with 20-20-20 liquid fertilizer twice a week.

Features This Season

“A 2017 National Recipe from Proven Winners is the one we used last year and this year in the hayracks downtown,” Kortan said. “It’s Vista Supertunia Bubblegum, Fuchsia, and Silverberry petunias.”

In pots by the hayracks in the Meridian District, she plans to use Prince Tut ornamental grass, ‘Jester’ millet, ‘Angel Face’ blue snapdragons and sweet potato vine. She may include one of the three hayrack petunias to coordinate colors. She tried a papyrus near the swimming pool last year. This year it has a more prominent location. She plans to include a Stratosphere White in the pots that she grew along Douglas last year. It has white flowers on spikes. The millet seed head matures and she may leave the plant in for fall display.

Kortan is planning to try Supertunia ‘Bordeaux’ in hayracks at the city golf course this season. It is a lavender flower with a purple center. She has used the petunia in planters along Douglas. If ‘Bordeaux’ performs well in the hayracks, it will provide a new color option for downtown. She also looks at the Yankton Ace Hardware greenhouse for some different plants to try. She goes to Menards for arrangement fillers and supplies.

She looks at the Proven Winner website at www.provenwinners.com for ideas. Search “Container Garden Design-Color” for articles on choosing container garden plants of your color interests. She also confers with Diane Dickes of Diane’s Greenhouse for combinations that Diane is growing.

“When I take the petunias down at the end of the season in September, and my truck is full of blooms, it doesn’t feel right. But it is the end of the season,” Kortan said.

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