Photo courtesy of Smith Gardens

Every plant trial is different. Each trial garden has different weather conditions, sunlight levels, water needs and other factors that make each location unique. That can make knowing which plants are best to grow at your local greenhouse or wholesaler a difficult question to answer. It’s also a tough question for you when deciding what plants to include in a design or where to place them in a customer's landscape.

Fortunately, trial gardens are here to help fill in the knowledge gap. Run, organized and staffed by trial managers who track every detail of every plant in their gardens, trial gardens help growers understand new varieties of annuals and perennials. They also test for different attributes like pollinator friendliness and drought tolerance, and note which plants have the “wow” factor consumers are looking for.

For these 2019 compilation of trial garden results, managers from across the U.S. submitted what performed best in their region in the following eight categories: best drought-tolerant annual; best drought-tolerant perennial; best pollinator-friendly annual; best pollinator-friendly perennial; best heat-tolerant annual; best heat-tolerant perennial; best overall performance: annual; best overall performance: perennial.

Here, you’ll find the results for each of these categories. All of the descriptions have been submitted by the various trial garden mangers.

Best Overall Performance


Calibrachoa Superbells ‘Honeyberry,’ Proven Winners, University of Georgia

Yep, I’m smitten with this plant and who wouldn’t be? I love that it has abundant pink flowers with honey-colored throats. It has remained perfectly shaped despite rain, shine, heat and humidity. Nothing phased ‘Honeyberry,’ which decidedly takes my top spot for annuals for 2019.

Caladium Bottle Rocket, Classic Caladiums, Young’s Plant Farm

The colors of Bottle Rocket caladium are phenomenal. This caladium has everything: dark red, crisp white and bright green. This is a large fancy-leafed variety that just got better in the heat of the summer. It was really a standout in the Young's Trial Garden.

Helianthus 'Suncredible Yellow,’ Proven Winners, North Carolina State University

These uniform, well-branched, upright plants have rays of bright yellow petals around a brown center. Flowers are supported by sturdy stems, which make them great for cuts. They bloom all season long and no deadheading is required. Pollinators love these guys!


Alternanthera FanciFillers Choco Chili, Westhoff, Penn State University Extension

An excellent plant, with no foliar injury all season. This plant received an overall score of 5/5 in 2019. As a foliage plant, it exhibited superb growth and maintained a uniform habit. A number of visitors remarked on the foliar quality during field day.

Helianthus ‘Suncredible Yellow,’ Proven Winners, Boerner Botanical Gardens

There were so many good annuals this year. This baby bloomed its heart out and didn’t get floppy until the end of September. It was also a favorite of pollinators and guests alike.

Impatiens Beacon, PanAmerican Seed, The Gardens at Ball

This plant did not fail due to Impatiens downy mildew, and we had it planted in several locations on campus. Our shade landscape beds particularly looked amazing, and several guests made a stop there to take pictures and take notes.

Petunia Shortcake Blueberry, Syngenta Flowers, Mast Young Plants (Michigan)

New standalone series! Something to sweeten up the garden! Shortcake turns the table and brings novelty color in a package that also excels in the garden. A versatile habit that works well in small pots and combos, but will still size up for an impressive display in the garden. Combining a grower-friendly habit with a unique, stable flower pattern, Shortcake is sure to be a hit at retail.

Calibrachoa Superbells ‘Honeyberry,’ Proven Winners, University of Georgia
Photo courtesy of University of Georgia


Dahlia ‘City Lights Purple,’ Selecta, Colorado State University

This dahlia was Best of Show at Colorado State University. The dark foliage and flowers of this variety made a dramatic statement in the garden. The growth habit had excellent uniformity with upright plants that did not flop despite overhead irrigation. Plants had strong flower power and were favorites of the bees.


Begonia Viking XL Red on Chocolate, Sakata, Smith Gardens

Amazing dark glossy foliage and contrasting red flowers made this variety a real standout in the garden this year. It has a vigorous, well-branched habit and great landscape performance.

Best Pollinator-friendly


Salvia Purple & Bloom, Ball FloraPlant, University of Georgia

Sun up to sun down you will count honey bees, carpenter bees, butterflies and even the elusive hummingbird moth. They all find this plant enjoyable. ‘Purple and Bloom’ will make a great medium to large annual for any full-sun flower bed, especially if you want to watch your local six-legged visitors.

Salvia Mystic Spires, Ball FloraPlant, Colorado State University
Photo courtesy of Colorado State University

Cuphea Honeybells, Ball FloraPlant, North Carolina State University

Easy, carefree, low-growing plants that are very uniform in size. The plants are covered in beautiful, bicolor tubular flowers that are orange-rose and yellow color — quite the pollinator magnets. Standing still, you notice the plants literally vibrating from the pollinator activity! Exhibit excellent heat tolerance too.

Lantana Gem Compact Orange Fire, Danziger, Young’s Plant Farm

Gem Compact Orange Fire is a nice, tidy little lantana with a rounded growth habit. It was covered in bright reddish-orange flowers for most of the summer. Bees and butterflies love lantana, and this Gem was no exception.


Salvia Purple & Bloom, Ball FloraPlant, The Gardens at Ball

Salvia Purple & Bloom welcomed hummingbirds all season and it kept its compact shape with good-sized blooms in its container showcase, as well as in the landscape.

Cuphea Honeybells, Ball Seed, Raker-Roberta’s Trial Gardens

Not very showy at first glance but had an abundance of flowers that always had bees, butterflies and hummingbirds all over it.

Dahlia XXL Cancún, Dümmen Orange, Mast Young Plants

MYP has exclusive rights to these cuttings for 2020. This will not be released to the entire market until 2020/2021. Amazing flower and garden performance.

Salvia Rockin’ Blue Suede Shoes, Proven Winners, Boerner Botanical Gardens

Butterflies and hummingbirds alike covered this plant pretty regularly. It’s also a bumblebee magnet.


Salvia Mystic Spires, Ball FloraPlant, Colorado State University

Another dependable performer and past winner, it stood out again in 2019 for the abundant dark purple flowers and vigorous, upright plants. Foliage was clean and glossy. This was another bee-friendly plant that was often buzzing with excitement.


Salvia Skyscraper series, Selecta One, Smith Gardens

This is our second year having Salvia Skyscrapers in the garden and they continue to be a pollinator favorite. Bees, butterflies and hummingbirds all flock to these plants, which were covered in flowers and looked fantastic all summer.

Best Heat-Tolerant


Helianthus Suncredible ‘Yellow,’ Proven Winners, University of Georgia

Seven … seven months! This plant bloomed for over half of our calendar year and that should tell you all you need to know about heat tolerance. Georgia had a tremendously hot summer and Suncredible ‘Yellow’ just shrugged it off like, “I’m good, I’ll just keep blooming.”

Lantana 'Luscious Goldengate,’ Proven Winners, North Carolina State University

Well-branched, compact plants that are covered in golden yellow flowers and frequented by pollinators. They were easy to grow with no deadheading needed. Takes our heat and keeps on shining!

Coleus ColorBlaze Wicked Witch, Proven Winners, Young’s Plant Farm

Coleus is always a winner in our garden. They perform great in the heat and humidity of an Alabama summer. ColorBlaze Wicked Witch was particularly nice, with deep purple foliage contrasted nicely with the ruffled green leaf edge. This coleus was also very late to flower and retained a great compact growth habit all season.

Top Left: Helianthus Suncredible ‘Yellow,’ Proven Winners, University of Georgia, Top Right: Lantana ‘Hot Blooded,’ Syngenta, Raker-Roberta’s Trial Gardens, Bottom Left: Lantana ‘Luscious Goldengate,’ Proven Winners, North Carolina State University, Bottom Right: Coleus Stained Glassworks Royalty, Dümmen Orange, Mast Young Plants
(clockwise from top left); University of Georgia; Raker-Roberta’s Trial Gardens; North Carolina State University; Mast Young Plants


Petunia ColorRush White, Ball FloraPlant, The Gardens at Ball

Petunia ColorRush White from Ball FloraPlant was planted in our skyframe garden as well as a container showcase. It was a bright, crisp white all season and its blooms bounced back from harsh weather and storms.

Lantana ‘Hot Blooded,’ Syngenta, Raker-Roberta’s Trial Gardens

This looked great throughout the summer with lots of bright flowers.

Angelonia Carita Purple, Syngenta Flowers, Penn State University

All angelonia cultivars performed very well in the PSU Flower Trials, but Carita Purple was an excellent performer and bloomed strongly throughout the growing season. Carita Purple received 5.0/5.0 scores for flowering on the first two ratings.

Coleus Stained Glassworks Royalty, Dümmen Orange, Mast Young Plants

Brings a bold splash of color to shade gardens. Excellent habit that adds texture and interest to mixed combinations. Suitable for solo and combo plantings.

Vinca ‘Soiree Kawaii Coral,’ Suntory, Colorado State University
Photo courtesy of Colorado State University


Vinca ‘Soiree Kawaii Coral,’ Suntory, Colorado State University

Tiny coral-colored flowers were bright and prolific, making an impressive display of color in either ground or containers. Additional features were the small white eye on the bloom and glossy green foliage. Plants stayed compact all summer long with no leggy branches.


Osteospermum Zion Purple Sun, Selecta One, Smith Gardens

In the Pacific Northwest, we generally don’t get very hot, but even our mild summer temperatures are too high to keep most osteospermums blooming into summer. Zion Purple Sun remained covered in striking multi-toned flowers in mid-July and continued blooming into August. Great mounded habit, no splitting.

To see all of the plants, visit our sister publication, Greenhouse Management Magazine here