URBANA, Ill. – Experienced container gardeners likely know that successful containers have good drainage, appropriate sun exposure, and proper potting media. Get a jump on new annual arrivals each year, discover the best performers, and be the envy of your neighborhood this summer by building beautiful container gardens.

A simple way to design a container is using the ‘thriller, filler, spiller’ method. Thrillers serve as a focal point and are usually vivid and tall, while fillers have a mounding, round shape that fill the container. Spillers are plants that drape over the sides of the pot with a vining habit.

An attractive container might include perennials, grasses, tropicals, or even herbs in addition to those colorful annual flowers. To make an impact, use varying heights, textures, and contrasting colors in hanging baskets, and identify a thriller, filler, and spiller for each container.

Armed with a vision, you can begin the fun of choosing plants. Have you ever brought home a carload of flowers in every color and thought where do I start? Avoid this dilemma by resisting the impulse to buy the entire rainbow. To create harmonious containers that look professionally assembled, go to the garden center with a color palette in mind. This will simplify the process and help your budget.

Instead of choosing the same old combinations of annuals – we see you red, white, and blue petunia baskets – consider some of the newest available varieties for an eye-catching design. To know which new varieties perform well, look no further than trial gardens.

What are trial gardens?

Trial gardens are one way plant breeding companies test new varieties. Trial gardens are grown in many locations, so breeders understand how plants perform in different climates and conditions. Garden growers such as volunteer groups, municipalities, private companies, commercial breeders, or universities must apply to host a trial garden. 

Plant breeders send seeds or cuttings to the approved growers, who continue growing and then plant them. Once planted, a rating scale is used to regularly assess each variety throughout the growing season. Gardeners recorded characteristics like performance, color, vigor, uniformity, insect and disease resistance, and uniqueness.

All-America Selections is an independent non-profit organization that supports trial gardens in nearly every state. Only the best garden performers become All-America Selections. Seeing “AAS Winner” on a plant tag means it has been tested by horticultural specialists and gained a seal of approval for its superior performance.

There are trial gardens across the country, some growing for one plant breeder, some growing for several. Gardens might choose to trial only edible plant varieties, only annual flowers, or only perennials. Some gardens test them all.

In Illinois, there are several opportunities to visit trial gardens, including one at the Idea Garden in Urbana. Champaign County Master Gardeners maintain and evaluate new varieties there each year and are overjoyed to share their knowledge on their 2022 trials.

A few of their favorites include:

• Calibrachoa Superbells® Coral Sun
• Gomphrena Truffula Pink
• Helianthus Suncredible Saturn, Suncredible Yellow
• Ipomoea (sweet potato) Illusion® Penny Lace™, Sweet Caroline Medusa Green
• Nemesia Aromance® Mulberry
• Petunia Supertunia Mini Vista®: Midnight, Scarlet, Yellow, Hot Pink, Pink Star, White
• Petunia Supertunia® Persimmon, Vista Jazzberry
• Plectranthus (coleus) ColorBlaze® Mini Me™, Watermelon, Pineapple Brandy, Torchlight
• Portulaca Mojave® Yellow 2023

To see other 2022 trial results, visit Michigan State University trial garden or Penn State University trial garden. Compare choices with a 2022 Top 10 Annuals list from University of Minnesota Extension.

If you are new to container gardening, visit the Good Growing blog at go.illinois.edu/ContainerGardenTips, for help with creating successful plantings. For more research-based information on gardening, connect with your local Illinois Extension county office at go.illinois.edu/ExtensionOffice.

Sarah Vogel is an Illinois Extension horticulture educator for DeWitt, Macon, and Piatt counties. Gardeners Corner is a quarterly newsletter from gardening experts around the state. Each issue highlights best practices that will make your houseplants, landscape, or garden shine in any season. Join the Gardener’s Corner email list at go.illinois.edu/GCsubscribe for direct access to timely tips.

ABOUT EXTENSION: Illinois Extension leads public outreach for University of Illinois by translating research into action plans that allow Illinois families, businesses, and community leaders to solve problems, make informed decisions, and adapt to changes and opportunities.

Photos: Proven Winners Nemesia Aromance Mulberry. Photo credit: All-America Selections. Photos available to download for media use from All-America Selections.