The verdict is in

Features - Cover Story

Trial garden managers from across the U.S. share this year’s top performers.

December 29, 2015

Compiled by Cassie Neiden

Photo Courtesy of Young’s Plant Farm

It’s been a profitable year for growers, according to our State of the Industry survey. However, 2015 brought interesting challenges for plants in the landscape. Obstacles to a plant’s thriving and surviving now include being pollinator friendly, drought and heat tolerant, all while bringing the flowering, height and habit that we’ve always appreciated, and that our customers expect.

We surveyed 18 trial gardens from Washington to Florida to discover which varieties stood up to those new challenges in their gardens, and more importantly, why. All comments come straight from trial managers.

Whether you’re simply curious or looking to add some last-minute varieties to your lineup next year, take note of these best-in-show options.

West Region

Best overall performance (annual)

A. Bidens ‘CUPCAKE’ Strawberry (PlantHaven), PlantHaven Trial Gardens

Prolific bloomer, color different from usual yellow on the market, long flowering, no seed set.

B. ‘Sunpatiens’ Spreading Tropical Orange (Sakata), Colorado State University

Electric orange flowers were vivid and had a great contrast against beautiful foliage. Plants maintained a high level of flower power all season. It has impressive vigor while the growth was very uniform. Foliage was very attractive all by itself with a dark green edge and bright yellow center. Plants grew well in full sun but are also adaptable to light shade.

C. Begonia ‘Elatior Vermillion Red’ (Beekenkamp), Smith Gardens

Begonias seemed to be a theme this year for trials but this one is a showstopper. The amount of extremely vibrant red flowers that this variety showcases is amazing. It withstands diverse weather better than most of the varieties in trials this year.

All Photos Courtesy of Respective Trial Garden Managers

Best overall performance (perennial)

A. Dianthus ‘DEVON COTTAGE’ Pinball Wizard (PlantHaven), PlantHaven Trial Gardens

Interesting pink and white striped coloration, great cut flower, fragrant, repeat bloomer.

B. Hibiscus ‘Summerific’ Cherry Cheesecake Hibiscus (Proven Winners - Walters Gardens), Colorado State University

This perennial could be seen from a distance, standing almost 5 feet high with flowers up to 7 inches across. Peak bloom was in late August/September when plant was covered with white and red flowers. We planted this in 2014 and had 100-percent survival rate.

C. Hypericum ‘Hypearl Compact Red’ (Aris Greenleaf), Smith Gardens

This plant breaks naturally without pinching, giving it a great mounded form. The dark leaves allow the yellow flowers and red fruit to stand out. Hypearl flowered early and for months.

Best drought-tolerant annual

A. Isotoma ‘FIZZ N POP’ Glowing Violet (PlantHaven), PlantHaven Trial Gardens

Prolific bloomer, heat tolerant. Long season of interest, summer-fall. Pollinators love it.

B. Celosia ‘Dragon’s Breath’ (Sakata), Colorado State University

This variety gained a lot of praise, even before it started flowering, for its beautiful burgundy colored foliage. Flowers formed late but were definitely worth the wait as they had a two-toned combination of burgundy and hints of fluorescent purple that seemed to glow. The vigorous plants had good garden presence all season. It would make a great textural accent for combination plantings.

Best drought-tolerant perennial

A. Leucanthemum ‘Real Sunbeam’ (PlantHaven), PlantHaven Trial Gardens

Beautiful colorfast yellow, strong bloomer, early-mid summer, repeating in fall. Hardy plant, drought tolerant once established. Improved disease resistance.

B. Achillea New ‘Vintage’ Rose Yarrow (Darwin Perennials), Colorado State University

Plant proved to be vigorous, despite competing with three other Achillea varieties planted next to it. It grew to about 30 inches in height which was taller than other yarrow varieties planted in trial. It had vigorous growth and was drought tolerant, but also produced many rose and white flowers throughout the growing season.

Best pollinator-friendly annual

A. Dahlia ‘PAINTER’ Berry Impressions (PlantHaven), PlantHaven Trial Gardens

Huge flowers with unique bold coloring. No staking needed. Good cut flower.

B. Lobularia ‘Raspberry Stream’ (Danziger ‘Dan’ Flower Farm), Colorado State University

Extreme flower power was combined with an intense raspberry color for an impressive flower display. The unique raspberry flower color was also noted for a nice, cream-colored eye for a slight two-toned effect, which was very attractive. Overall, it had a very uniform growth habit which held its shape, and the plants maintained a clean appearance all season. Bees loved it, and it also had a nice, sweet fragrance.

C. Salvia ‘Black & Bloom’ (Ball Floraplant), Smith Gardens

A new, dark-flowered Salvia that Bees love. Salvia ‘Black & Bloom’ is a heat loving, vigorous garden plant that flowers from May to September.

Best pollinator-friendly perennial

A. Salvia VIBE ‘Ignition Purple’ (PlantHaven), PlantHaven Trial Gardens

Vivid purple blooms on drought tolerant, grower friendly salvia. Compact tight rounded habit, 24 inches x 24 inches at maturity. Well mannered. Pollinators love it

B. Nepeta ‘Cat’s Meow’ Catnip (Proven Winners, Walters Gardens), Colorado State University

This variety proved to be the favorite for bees and other pollinators in our trials this season. Its peak bloom was in June, and it gave off a strong aroma at that time. It was a vigorous grower with plenty of flowers for pollinators. It was planted in 2014 and had 100-percent winter survival.

Buddleia Buzz ‘Hot Raspberry’ (Thompson & Morgan), Smith Gardens

A beautiful new color to the Buzz series. This buddleia is a butterfly magnet. A dwarf variety that is ever blooming with bright, saturated, raspberry-colored flowers.

Best heat-tolerant annual

A. Abutilon ‘PATIO LANTERN’ Passion (PlantHaven), PlantHaven Trial Gardens

Beautiful watermelon pink bell shaped flowers on a compact plant. Heat and drought tolerant once established. Great for hanging baskets.

B. Lantana ‘Lucky Sunrise Rose’ (Ball FloraPlant), Colorado State University

This has been an award winner in the past, and has become a perennial favorite in our trials. The brightly colored flowers were very prolific, and the dark foliage color really made the flower color pop. Plants were vigorous, but maintained a uniform growth habit.

Vinca Valiant Series (PanAmerican Seed), Smith Gardens

This new series is a genetic improvement on the Titan series. The Valiant series overall habit is improved, but it still carries on with its heat tolerance and flower power.

Best heat-tolerant perennial

A. Gaillardia REALFLOR ‘Sunset Cutie’ (PlantHaven), PlantHaven Trial Gardens

Drought tolerant once established. Two-toned red bronze and cream bold colorfast blooms age well on long blooming plant. Very floriferous. Bee magnet.

B. Perovskia ‘Little Lace’ Russian Sage (Conard-Pyle Co.), Colorado State University

Many plants struggled in our July and August heat; this perennial survived the heat and was the largest of its kind in the trials. We planted it in 2013 and it has survived two winters with 100-percent survival over two winters and three growing seasons. It grew to about 3 feet tall and wide.

C. Agastache ‘Peachy Keen’ (Proven Winners - Walters Gardens), Smith Gardens

Most Agastache varieties will start to split and fall over in the heat of the summer, Agastache ‘Peachy Keen’ does not. We had one of the hottest summers in years here in the Pacific Northwest and this beauty flowered from June through August and looked great the entire time.

Southeast Region

Best overall performance — annual

A. Angelonia Archangel (Ball Seed), Costa Farms

This variety continues to impress us with its uniform and colorful display of flowers. It has also demonstrated remarkable resistance to pests and disease and is a great fool-proof plant for beginner gardeners.

B. Begonia ‘BabyWing’ Pink Bicolor (Pan American Seed), Mississippi State University

This new hybrid produced plants of similar size to standard wax begonias, but stood up to the summer heat and flowered from spring into the fall. The bicolored flowers were unique in comparison to solid-colored begonia flowers

C. Petunia ‘Tidal Wave’ Red Velour (PanAmerican Seed), University of Tennessee

This outstanding variety spread nicely, mounded as it should and withstood rain and wind. Also, it never got leggy or had stems that quit blooming in the center. It always looked fresh and unweathered. The color was fantastic.

D. Coleus Party Time Pink Berry (Sakata), Young’s Plant Farm

Nice, compact spreading growth habit and preformed equally well in sun and shade.

E. Petunia ‘Supertunia Vista Bubblegum’ (Proven Winners), North Carolina State University

It stayed covered in medium sized, beautiful, clear deep pink flowers all summer. It’s also vigorous— it'll fill an area 4 to 5 feet wide.

Best drought-tolerant annual

A. Pentas lanceolata ‘Northern Lights Lavender’ (Benary), Mississippi State University

Although bred for flowering in cooler climates, this Egyptian starcluster has been a reliable performer in our trial gardens for several years. Plants thrive in the heat and also attract pollinators.

B. BIG Begonia (Benary), Costa Farms

Tried and true the Begonia Big series from Benary is about as easy to grow as you can get. The plants are incredibly adaptable to environmental fluctuations including temperature, sunlight and humidity. This plant is tough and will handle neglect while tirelessly pumping out colorful blooms.

Lantana ‘Lucious Pinkberry Blend’ (Proven Winners), University of Tennessee

Beautiful, bright, rich color was covered in blooms well above the foliage.

C. Ipomoea ‘Solar Power’ series (Ball FloraPlant), Young’s Plant Farm

Slightly more compact and the red variety held its color in full sun without fading.

Sweet Potato ‘SolarPower Red’ (Ball FloraPlant), North Carolina State University

‘SolarPower Red,' like all sweet potatoes, was tough as nails when it came to flourishing in the heat with little water.

Best overall performance – perennial

A. Gaura ‘Grace Blush’ (Danziger ‘Dan’ Flower Farm), Costa Farms

A low-maintenance plant that is well suited for the landscape and container gardening. The airy display of flowers lends a soft and appealing impression to any garden setting.

B. Colocasia esculenta Black Coral – Royal Hawaiian series (PlantHaven International; provided by AgriStarts), Mississippi State University

Black Coral has performed exceedingly well in full sun in our Trial Gardens. Planted in spring of 2014, all plants survived the winter (dormant beneath their pine straw mulch) and returned to provide a lush, tropical display of dark black leaves in 2015. Visitors love the foliage color.

C. Sedum ‘Pure Joy’ (Proven Winners), University of Tennessee

Short in stature (6 to 8 inches), Pure Joy set buds early, and was a delight as buds opened pink in summer, forming a dense mat of blooms. Slowly over the course of the fall, they deepened to a russet color.

D. Coreopsis ‘Leading Lady Lauren’ (Dümmen Orange), North Carolina State University

She performed well no matter what the condition. All the plants of ‘Leading Lady Lauren’ bloomed heavily on sturdy green mounds.

Best drought-tolerant perennial

A. Canna Cannasol (Dümmen Orange), Costa Farms

As this is often considered a tropical plant, you may not automatically associate it with drought tolerance but as other plants wilted in the garden, this variety stood strong.

B. Ruellia simplex Mayan White (University of Florida), Mississippi State University

This sterile form of Mexican petunia thrives in the heat and can handle periods of drought, but performs best with regular watering. Spent flowers drop from the plant, unlike the old seed-producing Snow White, which tended to retain its old, brown flowers. The flowers of Mayan White also attract bumblebee pollinators. Planted in spring 2014, plants went dormant in winter and all returned in 2015 for a second year of flower production.

C. Sedum ‘Lemon Coral’ (Proven Winners), University of Tennessee

Specimens were planted next to pavement in full sun and couldn’t have been in a more challenging site, but Lemon Coral was outstanding and caught everyone’s eye. Bright chartreuse turns to brilliant coral in fall.

Best pollinator-friendly annual

A. Lantana ‘Bandana Rose’ (Syngenta Flowers), Costa Farms

Lantana Bandana Rose was one of the preferred plants for our local monarch butterfly population in the garden. This plant was always abuzz with honeybees and butterflies and would make a great addition to any butterfly landscape.

B. Ocimum basilicum Dolce Fresca (PanAmerican Seed), Mississippi State University

The mounded plants are ornamental on their own, the leaves can be harvested for culinary use, the white flowers attract an abundance of pollinators and the plants grow back easily after a harvest.

Salvia ‘Summer Jewel Red’ and ‘Summer Jewel Pink’ (American Takii), University of Tennessee

It didn’t matter what color of the Summer Jewel series was evaluated — all attracted pollinators of every kind, including bees, butterflies and hummingbirds. Also withstood heat and drought.

C. Cuphea Vermillionaire (Proven Winners), Young’s Plant Farm

This variety was covered with orange flowers that the bees loved, plus it is very heat and drought tolerant.

Salvia ‘Black & Bloom’ (Ball FloraPlant), North Carolina State University

One morning, I saw a humming bird working the flowers. The bees especially liked this one.

Best pollinator-friendly perennial

A. Salvia Cathedral Shining Sea (GreenFuse Botanicals), Costa Farms

The violet-blue flowers of this perennial have always attracted attention from gardeners. Coincidentally, honeybees also found the flower to be appealing.

B. Agastache rugosa Golden Jubilee (Sahin), Mississippi State University

The light bluish-lavender flowers contrast well with the golden-green foliage, and the foliage has the bonus of a pleasant anise scent.

C. Eutrochium ‘Little Joe’ Joe-pye weed (North Creek Nurseries), University of Tennessee

Late summer bloomer really attracted pollinators but was also valued for its short (2.5 to 3 feet) strong stems that kept the plant from lodging or blowing over.

Salvia 'Salute Deep Blue' (Dummen Orange), North Carolina State University

A favorite of many of the bees and skippers.

Best heat-tolerant annual

Vinca Soiree Kawaii Coral (Euro American), Costa Farms

As you can imagine, this summer was very hot in Miami and as other plants flagged with the heat, you could find the Vinca Soiree Kawaii Coral from Euro American thriving. This plant loves the sizzling summer conditions here in Florida and for that reason we love it.

A. Ipomoea batatas SolarPower Black (Ball FloraPlant), Mississippi State University

Plants of this ornamental sweet potato showed a more restrained growth habit than the rapidly spreading varieties that have been on the market, making SolarPower Black useful in the ground, containers and baskets. Plants developed a solid cover of foliage over the ground beds and the foliage retained its dark black color from spring through fall.

Portulaca ‘Mojave Tangerine’ (Proven Winners), University of Tennessee

The Mojave series of portulaca was outstanding because the blooms stayed open longer than what is typically expected with portulaca. Color selection was outstanding.

B. Vinca Valiant Series (PanAmerican Seed), Young’s Plant Farm

This variety is vigorous and makes an excellent landscape item. It had no trouble blooming all summer.

Lantana 'Luscious Pinkberry Blend' (Proven Winners), North Carolina State University

"The hotter, the better" is the mantra for this variety. As an added bonus, the butterflies and bees are attracted to this beauty.

Best heat-tolerant perennial

A. Ruellia simplex Mayan Purple (University of Florida), Mississippi State University

Mayan Purple has a growth habit similar to Mayan White, but with purple flowers. Plants are sterile and attract bumblebees. The hottest weeks of summer provided the most abundant flowering. Planted in spring 2014 and dormant during winter, most plants returned for a second year of evaluation in 2015.

Salvia greggii ‘Heatwave’ Glitter (Monrovia), University of Tennessee

Brilliant color and a long bloom time made this a choice for top perennial. Good branching habit resulted in full form.

Echinacea 'Prairie Splendor Rose Compact' (Syngenta Flowers), North Carolina State University

This variety thrived in our heat and humidity and showed off with beautiful flowers. The pollinators enjoyed it during the summer, and the birds will enjoy the seeds this winter.

B. Coreopsis Solanna Glow (Danziger ‘Dan’ Flower Farm), Costa Farms

One of the main challenges we have growing perennials in South Florida is the heat. Not many perennials can handle the high afternoon temperatures and sultry nights here and that is why we were so impressed with the Coreopsis Solanna Glow from Danziger. Even with the midday heat, this plant did not falter in producing bright blooms.

Midwest Region

Best Overall Performance — Annual

A. Celosia, Dragon’s Breath (Sakata), Ohio State University Cultivar Trials

Rated on four grower performance evaluations throughout the year. High ratings on all four.

B. Coleus ColorBlaze ‘Apple Brandy’ (Proven Winners), Kansas State University

This new cultivar was superb in its branching and shape. The serrated leaves displayed excellent color in both full sun and deep shade and had a soft layering effect that gave the plantings a very full look.

C. BIG Begonia series (Benary), Michigan State University

This series looks full and well-established after transplanting them outside, and continues to improve to form a vigorous mount about 3 feet tall by the end of the season.

D. Coleus ‘FlameThrower’ Spiced Curry (Ball FloraPlant), The Gardens at Ball

Very showy coleus with an interesting leaf shape. Held its color all season and filled its beds/pots nicely.

Dianthus Jolt series (PanAmerican Seed Company), Reiman Gardens

Both ‘Jolt Pink’ and ‘Jolt Cherry’ bloomed all season long with bright colors. They do need to be caged early in the season, as our rabbits are ravenous, but they were fine by themselves by mid-June. They are both easy to grow from seed in the greenhouse and transplant well. Our entries stay on the shorter side, around 14 to 18 inches, which is a perfect height.

E. Celosia Intenz Classic (Ball Ingenuity), Mast Young Plants

Chosen for intense color, long-lasting flowers, great garden performance and season-long blooming.

F. Petunia ‘Tidal Wave Red Velour’ (PanAmerican Seed), Boerner Botanical Gardens

This petunia just never stopped blooming and spreading. No sign of Botrytis on the blooms, and it quickly self-cleans. Would be gorgeous cascading down a wall. Even on flat ground, the deep red color is hard to beat.

Best overall performance – perennial

A. Echinacea ‘Sombrero’ Baja Burgundy (Darwin Perennials), The Gardens at Ball

Striking color for a coneflower. Plants were compact, branched well and had a long bloom season.

B. Salvia Blue Marvel (Growing Colors), Mast Young Plants

Chosen for the full habit, garden performance and large blue flowers (larger than other nemerosa type salvias).

Vernonia ‘Southern Cross’ (Intrinsic Perennial Gardens), Boerner Botanical Gardens

A show-stopper once it starts blooming in August. No sign of flopping over and often covered in pollinators.

C. Hibiscus SUMMERIFIC ‘Perfect Storm’ (Proven Winners), Walters Gardens

This naturally compact plant doesn’t require as heavy of PGR applications as other hardy Hibiscus varieties. The foliage needs direct sunlight to develop its dark color; growing it under plastic will cause the foliage to look greener. Growing in direct sunlight is the best method for both finishing and best coloration. Starting from bare root, I grow Hibiscus ‘Perfect Storm’ outdoors and finishing in six to eight weeks, with huge 7- to 8-inch white flowers with pink accents appearing in August.

Best Drought-Tolerant Annual

A. Portulaca ‘Cupcake’ series (Dümmen Orange), Kansas State University

These plants were vigorous growers that held up well through prolonged dry periods and put on abundant blooms. The colors were some of the brightest in the flower trials in the early afternoon sun.

B. Vinca Valiant series (PanAmerican Seed), The Gardens at Ball

A new series of disease-resistant Vinca that established in the garden even with the cool/damp start to the season. Performed well and stayed in color through the dry August and September months.

C. Ageratum Blue Planet (Johnny’s Selected Seeds), Mast Young Plants

Chosen because of all the drought-tolerant annuals we had, this one looked great all summer and it stands out as being a more vigorous ageratum.

Best drought-tolerant perennial

A. Verbena rigida Santos Purple (PanAmerican Seed), The Gardens at Ball

A real crowd-stopper this summer. It is very free flowering with rich purple flower clusters, and it’s never out of bloom. It keeps going until frost.

B. Perovskia Caspian Blue (Green Fuse Botanicals), Mast Young Plants

This perovskia stood out among other drought-tolerant perennials for how full it was and also for its floriferousness.

C. Baptisia DECADENCE ‘Pink Truffles’ (Proven Winners), Walters Gardens

‘Pink Truffles’ is very exciting in terms of flower color. Typically, you’ll see blue or yellow flowers on this native plant, but ‘Pink Truffles’ is one of the first on the market to bloom a soft pink. I prefer to start Baptisia in June here in Michigan, starting from a small plug and growing outside under natural conditions.

Best pollinator-friendly annual

A. Asclepias ‘Monarch Promise’ (Hort Couture), Kansas State University

The pink and white variegated leaves made this cultivar really unique and eye-catching. The variegation held all summer and the plants put on multiple flushes of attractive bright orange flowers. It was a great food source for many Monarch caterpillars.

B. Salvia ‘Black & Bloom’ (Ball FloraPlant), The Gardens at Ball & Boerner Botanical Gardens

Ball: The Gardens never had so many hummingbird visitors. Our bees enjoyed the plants as well. The black stems and blue flowers stood out and were a favorite among visitors.

Boerner: This plant often had six hummingbirds fighting over the flowers on it. Bumblebees also were often seen trying to wedge their fuzzy selves into the flowers.

Salvia ‘Summer Jewel’ (American Takii), Reiman Gardens

This series is very popular in our gardens for bees, butterflies and other pollinators. Vigorous re-seeder, so be aware that wherever you place it, it will be there at least a year after. Naturally low-growing, so there are no flopping issues like some of the taller Salvia coccinea on the market. Clear white color, great compact height, and a favorite with wildlife.

Bidens, Giant White (Westoff), Ohio State University Cultivar Trials

We have an apiary nearby, this plant was covered in honey bees all season.

C. Bidens Beedance Painted Red (Suntory), Mast Young Plants

This bidens is unique for its bicolor flowers and did great in our beds although it was a bit on the vigorous side. Plants from the same source, also without any growth regulation, did well in baskets and were controllable in those. Flowered all season and very attractive to bees, especially.

Best pollinator-friendly perennial

A. Lobelia Starship Deep Rose (Burpee), The Gardens at Ball

Outstanding color with a pearl-like center. Mixed well in containers and the upright blooms caught the eye in the perennial beds. Tender perennial (zone 6).

Agastache ‘Little Adder’ (Darwin Perennials), Boerner Botanical Gardens

A butterfly favorite in the trial garden. This was a first-year planting, and we’re excited to see how it survives the winter and performs in following years.

B. Phlox ‘Opening Act White’ (Proven Winners), Walters Gardens

It’s the scent that’s drawing in the pollinators such as butterflies and hummingbirds. I recommend growing ‘Opening Act White’ from bare root since it yields a greater amount of stems in a short time. Along with ‘Opening Act Blush’, these new hybrid types of Phlox will bloom earlier in summer — about three weeks earlier in the ground. ‘Opening Act White’ has pure white flowers that will rebloom, especially if you sheer the plants back after blooming.

Best Heat-Tolerant Perennial

A. Gaura ‘Belleza’ and Gaura ‘Sparkle White’ (Kieft Seed), The Gardens at Ball

These lasted through the heat of the season and held their flowers, providing great texture in the perennial beds and in display areas.

B. Gaura ‘Little Janie’ (Darwin Perennials), Mast Young Plants

Flowers well all summer and has unique rosy pink and white bicolor flowers.

C. Agastache ‘Mango Tango’ (Proven Winners), Walters Gardens

This variety will finish a trade gallon pot in 8 to 10 weeks and is relatively carefree. I love these new types of Agastaches (‘Rosie Posie’ and ‘Peachie Keen’ came to the market last year) because of their round habits and long bloom times. ‘Mango Tango’ is a darker orange than ‘Peachie Keen’ with more of a red-orange color.

Best heat-tolerant annual

A. Vinca (Catharanthus) ‘Valiant’ series (PanAmerican Seed), Kansas State University

These adaptable plants came on strong early in the season and stayed strong through the summer heat, blooming all season long. They thrived in western Kansas where temperatures are regularly above 100 degrees and the wind (almost) always blows.

B. Ipomoea Solar Power series (Ball FloraPlant), The Gardens at Ball

All three colors in the series were exceptional — either as mixed container components, in our vertical walls, and as groundcovers. Filled in nicely all season with no fade. Black especially was a standout.

Mandevilla, Summer Romance Double Pink (Ball Ingenuity), Ohio State University Cultivar Trials

In late July and August, the plant grew/thrived the most compared to other annuals.

C. SunPatiens Compact Royal Magenta (Sakata Ornamentals), Mast Young Plants

The SunPatiens, and this color in particular, are just powerhouses in the summer — growing and flowering well throughout. The Compact Royal Magenta was the top-performing of them all.

Northeast Region

Best overall performance — annual

Angelonia Archangel Dark Rose (Ball Flora Plant), Penn State University

Best overall performance — perennial

Heucherella Honey Rose (Blooms of Bressingham), Penn State University

Best pollinator-friendly annual

Lobularia Lavender Stream (Danziger), Penn State University

Best pollinator-friendly perennial

Monarda punctata BeeBop (Garden Genetics), Penn State University

Best heat-tolerant annual

Calibrachoa Aloha Tiki Neon (Dummen), Penn State University

Best heat-tolerant perennial

Perovskia Caspian Blue from (Green Fuse Botanicals), Penn State University

* photo not available

Southwest Region

Best overall performance — annual

Mandevilla ‘Sundenia Coral’ (Suntory), Dallas Arboretum

Mandevilla in general performs well for us, but ‘Sundenia Coral’ was absolutely stunning all summer long. The dark green foliage allows the bright punchy flowers to stand out from a distance. A perfect plant for summer.

Best overall performance — perennial

Pervoskia ‘Crazy Blue’ (Darwin Perennials), Dallas Arboretum

This is one of those few perennials that bloomed starting late spring and continued through the heat of summer, requiring no deadheading or pruning of any kind. Its nice, compact habit is just an added bonus.

Best pollinator-friendly perennial

A. Caryopteris ‘Blue Fountain’ (Proven Winners), Dallas Arboretum

‘Blue Fountain’ has been a top performing perennial for the past couple of years in our trials, and it is no secret that the pollinators love it too. It would be a challenge to snap a picture that didn’t have some sort of pollinator swarming the blooms.

Best drought-tolerant annual

Portulaca ‘Sun Dome White’ (Sakata Ornamentals), Dallas Arboretum

As a whole, the new ‘Sun Dome’ series performed well for us, but ‘Sun Dome White’ stood out because of its ability to continue to grow, not just maintain, and produce blooms through the hot, dry months of July and August. Another great feature is the mounding habit that created a solid mass, leaving no soil visable.

Best drought-tolerant perennial

Muhlenbergia ‘Pink Flamingo’ (Mountain States Nursery), Dallas Arboretum

Perennial grasses tend to be overlooked, but provide great options for perennial gardens that receive little to no supplemental irrigation. The great thing about ‘Pink Flamingo’ is its vigor and abundance of bloom stalks that have the slightest tinge of pink to add interest.

Best heat-tolerant annual

Celosia ‘Intenz Lipstick’ (Ball Ingenuity), Dallas Arboretum

We fell in love with ‘Intenz’ a few years ago when it was first released, and we were excited for a couple of new colors to trial. ‘Intenz Lipstick’ is very floriferous with a great habit and withstood our scorching summer heat with no issues.

Best heat-tolerant perennial

A. Achillea ‘New Vintage Rose’ (Darwin Perennials), Dallas Arboretum

Last year, with a relatively mild summer, ‘New Vintage Rose’ performed well, but this year was a true test of our perennial trials with a normal Texas summer complete with multiple days well over 100 degrees. We are happy to say Achillea ‘New Vintage Rose’ performed just as well this year, maintaining healthy foliage and loads of blooms all summer long.

Editor's Note:Comments were edited for length and clarity. Some trial sites were unable to provide selections for each category.