The Chicago Botanic Garden (USDA Hardiness Zone 5b, AHS Plant Heat-Zone 5) evaluated 49 Geum taxa between 2007 and 2015. Forty-six taxa completed at least two years in the trial, although the majority of the taxa were evaluated for four years. Three taxa were excluded from the final results because they were evaluated for one year only. The goal of the comparative trial was to identify outstanding avens for upper midwestern gardens.

Five plants of each taxon were grown in side-by-side plots for easy comparison of ornamental traits and landscape performance. The evaluation garden was openly exposed to wind in all directions and received at least ten hours of full sun daily during the growing season, which averaged 181 days per year for the trial period (see Table 1). The clay-loam soil had a pH of 7.4 throughout the evaluation term. The site was normally well drained, but at times the soil retained moisture for short periods in summer and winter. Geum canadense was planted in a partially shaded site that had a similar soil type and alkaline pH as the full-sun garden.

Maintenance practices were kept to a minimum, thereby allowing the plants to thrive or fail under natural conditions. Trial beds were irrigated via overhead sprinklers as needed, mulched with composted leaves once each spring or summer, and regularly weeded. Moreover, plants were not deadheaded, fertilized, winter mulched, or chemically treated for insect or disease problems.

In the spring of 2007, 26 taxa were planted in the full-sun trial garden; the remaining 23 taxa were added to the trial between 2008 and 2012 as new introductions became commercially available. All plants were evaluated for their cultural adaptability to the soil and environmental conditions of the test site; disease and pest problems; winter hardiness or survivability; and ornamental qualities associated with flowers, foliage, and plant habits. Final performance ratings are based on flower production, foliage and habit quality, plant health and cultural adaptability, and winter hardiness during the trial period. The plant traits and final performance ratings for 46 taxa are shown in Table 2. Geum ‘Feuerball’, G. ‘Lady Stratheden’ and G. quellyon ‘Double Bloody Mary’ died the first winter and were not retested, and are not included in the table. 

Sixty percent of the taxa received fivestar excellent or four-star good ratings for their overall performance in the trial. Top-rated plants displayed superior flower production, attractive foliage, robust habits, adaptability to the growing conditions of the site, and winter hardiness. The outstanding five-star rated avens included Geum ‘Mai Tai’, G. ‘Sangria’, G. ‘Totally Tangerine’, and G. triflorum.

Geum 'Mai Tai'

Geum 'Sangria'

Geum 'Totally Tangerine'

Geum 'Triflorum'

Geum ‘Mai Tai’ is one of the new avens with midwestern roots—bred by Brent Horvath in Hebron, Illinois. Apricot-flowered ‘Mai Tai’ is a delightful departure from the hot-color palette so typical of the group. Flowers open a muted red, fading to apricot with striking burgundy sepals and flower stems. The outward-facing, semi-double flowers bloomed generously from late April to early June and then again sporadically later in the summer. ‘Mai Tai’ averaged 24 inches tall and wide with flowers; without flowers the rounded foliar mound was 10 inches tall.

Like ‘Mai Tai’, Geum ‘Sangria’ is also part of the Geum Cocktail Series^™, and was one of the last avens to begin blooming, typically in early to mid-June. Its dazzling scarlet flowers—semi-double and upwardfacing— were borne profusely for more than a month and then rebloomed in August. The robust mounds topped out at 16 inches tall and 30 inches wide but the flower stems extended the height to 30 inches.

Geum ‘Totally Tangerine’ (synonym ‘Tim’s Tangerine’) shared an exuberance of bloom and plant size with ‘Sangria’. The branched floral stems, to 29 inches tall, were crowded with upward- and outward-facing tangerine-orange blossoms from late May to mid-July, and sometimes a bit longer due to the sterile nature of the flowers. We described the floral form as semi-double because each blossom had a few more petals than a typical single flower but far fewer than other semi-double cultivars. A robust mounded habit and an exceptionally floriferous nature set ‘Totally Tangerine’ apart from most other avens.

Geum triflorum, prairie smoke, is often characterized as a native plant, but its superior ornamental traits and cultural adaptability make it a great garden perennial. Its curious flowers—in groups of three— nod like a shepherd’s crook with the creamy white petals hidden beneath rosy pink spurred caps. The distinctive fruits developed while flowers were still blooming strongly; long feathery tails on maturing seeds turned silvery and pink, looking like puffs of smoke above the plants. The ferny foliage, strongly dissected into many leaflets, stayed attractive as long as the plants were kept moist. Prairie smoke is known to go dormant in severe drought conditions.

Geum 'Cosmopolitan'

Geum 'Spanish Fly'

Geum 'Wet Kiss'

Ornamentally, avens offer an array of flower colors and forms, generally prodigious flower production, attractive albeit somewhat coarse foliage, and variably mounded habits. Floral forms ranged from single to semi-double, and nodding to upward- and/or outward-facing; flower size ranged between 1 and 2 inches wide. The five petals on singleflowered forms were either overlapping or separated by a gap; the number of petals on semi-double flowers varied by cultivar, from a few more than five to many. Frankly, the generous floral display of Geum urbanum was underwhelming because of the wide gaps between the five petals. In the case of the nodding flowers of G. rivale and G. triflorum, the understated petals were hidden within colorful, cup-shaped coronal bracts that provided the real floral show. The nodding apricot flowers of G. rivale ‘Leonard’s Variety’ featured flared petals, which were far showier than the introverted flowers of the species. In some instances, the calyces and flower stems were exceptionally colorful, ranging from burgundy to maroon to reddish purple. Among the taxa exhibiting colorful calyces and stems were ‘Alabama Slammer’, ‘Cherry Cordial’, ‘Cosmopolitan’, ‘Mai Tai’, ‘Spanish Fly’, ‘Tequila Sunrise’, ‘Wet Kiss’, G. rivale, and G. rivale ‘Leonard’s Variety’. The plumose fruits of G. triflorum and G. montanum were the most ornamental among the avens; whereas, the fruits of G. coccineum, G. rivale, and G. urbanum were not as strongly feathered nor as colorful. Although seedlings were infrequently observed in the trial, G. urbanum was a consistently vigorous reseeder.

Geum coccineum 'Cooky'

Geum coccineum 'Werner Arends'

Geum 'Starker's Magnificum' 

All in all, leaves were large, variably pinnately dissected with prominent terminal lobes, medium to dark green, and remained healthy and ornamental as long as soils were consistently moist. Geum coccineum ‘Eos’ foliage started out bright yellow in the spring, turned mostly green in June but held about 20 percent yellow leaves all season. Plant habits were generally robust mounds, either rounded or flattened. The avens with low, flattened mounds included ‘Georgenburg’, ‘Pumpkin’, and G. coccineum ‘Eos’. Geum canadense was the only taxon that had a messy, sprawling habit in summer. Uneven or open habits were usually due to the varying degrees of crown loss during the previous winter.

Continual moisture is essential to keep avens healthy and green all summer, especially during hot periods. The most significant health or cultural issue that affected ornamental displays was the decline of foliage in mid- to late summer during hot, dry weather. While the crispy brown leaves created an unsightly display for a time, new leaves were eventually produced and covered up the dead foliage. The only avens that was consistently troubled by brown foliage each summer was ‘Summer Hummer’. Conversely, the leaves of ‘Starker’s Magnificum’ were lushly green and never burned nor bronzed even in the hottest weather. The yellow leaves of ‘Eos’ were prone to sunscald in full sun. Japanese beetles were an infrequent and insignificant pest in the trial; minor damage of little consequence was noted on a few plants over the years. Powdery mildew was limited to several taxa and considered an insignificant problem overall. However, minor mildew was observed each year on Geum rivale, G. rivale ‘Album’, and G. rivale ‘Leonard’s Variety’. Minor to moderate mildew was noted on G. montanum in one year, and moderate to severe mildew was observed on G. urbanum in all years.

The petals of all avens dropped cleanly, so the display immediately after flowering was not unpleasant. Avens are commonly touted as having good repeat bloom if deadheaded, but we made no determination one way or the other since we did not remove spent flower stems. Rebloom was noted on a number of taxa every summer (see Table 2) without deadheading. Left alone, the flower stems eventually blackened and created an unsightly display. Frequent division is commonly recommended to keep plants healthy and robust, but we did not observe any decline in crown vigor over the course of the trial. Crown injury during winter affected the habit quality of some avens but they usually rebounded the following summer.

Geum 'Borisii'

Geum 'Citronge'

Geum 'Fire Storm'

The majority of taxa were determined to be winter hardy with some exceptions noted. ‘Banana Daiquiri’, ‘Coppertone’, and Geum montanum were winter-killed after growing successfully for two years. Plants of ‘Mrs. Bradshaw’ lived for three years before dying in the winter of 2011–2012. All plants of G. urbanum died during two consecutive winters—2008–2009 and 2009–2010—but vigorous seedlings replaced the plants in each of the following springs. Only in the winter of 2010–2011 did all plants of G. urbanum make it through winter without injury—seedlings were also present in spring 2011. Geum ‘Blazing Sunset’ was never successfully overwintered despite being replanted in 2008, 2009, and 2010. Geum ‘Feuerball’, G. ‘Lady Stratheden’ and G. quellyon ‘Double Bloody Mary’ died the first winter (2007–2008) but were not retested. Incidentally, ‘Lady Stratheden’ is also known as ‘Gold Ball’, but plants sold under that name were not included in the trial.

Geum 'Flames of Passion'

Geum 'Limoncello'

Geum 'Rijnstroom'

Geum 'Fuzzy Navel'

The greatest plant losses and crown injury were observed during the winters of 2007– 2008 and 2013–2014, although winter injury was noted in every year of the trial between 2007 and 2015. In addition to the losses noted above, the highest attrition or crown damage was incurred by ‘Cherry Cordial’ (first attempt failed, second attempt succeeded), ‘Pumpkin’ (first attempt failed, second attempt died in third winter), ‘Sunrise’ (severe crown injury in first winter, complete plant loss the second winter), and Geum coccineum (severe crown loss in multiple winters). Avens with no winter losses or crown injury observed during the trial period included ‘Beech House Apricot’, ‘Borisii’, ‘Citronge’, ‘Cosmopolitan’, ‘Fire Lake’, ‘Fire Storm’, ‘Flames of Passion’, ‘Georgenburg’, ‘Gimlet’, ‘Limoncello’, ‘Lisanne’, ‘Mai Tai’, ‘Rijnstroom’, ‘Spanish Fly’, ‘Summer Hummer’, ‘Totally Tangerine’, G. canadense, G. coccineum ‘Eos’, C. coccineum ‘Werner Arends’, G. xintermedium ‘Diane’, G. rivale, G. rivale ‘Album’, G. rivale ‘Leonard’s Variety’, and G. triflorum.

Geum x intermedium 'Diane'

Geum 'Sea Breeze'

Avens are not common garden plants but their performance in the trial demonstrated that they should be grown more widely. The avens of old are being supplanted by a new crop of contemporary hybrids with a wider range of flower colors. Just over 60 percent of taxa in the trial received good or excellent ratings—‘Mai Tai’, ‘Sangria’, ‘Totally Tangerine’, and Geum triflorum were the highest rated plants. In the end, there was a good mix of old and new varieties among the top performers.

Avens are notably ornamental—exhibiting a range of flower colors and forms, bountiful floral displays, bold-textured foliage, and robust habits. Whether single or semi-double, nodding or up-facing, the miniature rose-like flowers are generously produced for a long period from late spring to midsummer. While not as exuberant in bloom, the nodding flowers of avens such as Geum triflorum and G. rivale possessed a certain charm despite the petals being hidden. Foliage was generally bold-textured and remained attractive all summer unless troubled by hot, droughty conditions.

Deadheading was the only maintenance deemed necessary to improve the ornamental display after flowering. Since we did not deadhead, there was no way to determine whether deadheading increased or promoted repeat bloom.

A good number of avens bloomed again later in the summer without deadheading. Removing spent flower stems would eliminate the unsightliness as they turn black, as well as reduce the chances of reseeding. Seedlings were rarely observed in the trial plots; however, Geum urbanum reseeded freely and was almost weedy in the garden.

By and large, the avens were winter hardy in zone 5 and grew vigorously for at least four years. With a reputation for being short-lived, more plant losses were anticipated than were observed. ‘Blazing Sunset’, ‘Mrs. Bradshaw’, ‘Lady Stratheden’, Geum quellyon ‘Double Bloody Mary’, and G. urbanum were either short-lived or possibly not winter-hardy. Based on our observations, these particular avens are probably best treated as annuals. Providing sufficient moisture throughout the growing season is important for maintaining strong, healthy plants. Foliar desiccation in hot, dry periods was observed but no plants were killed. In light of this, planting avens in afternoon shade in warmer regions is recommended.

The introduction of so many new and unique avens in recent years is exciting for gardeners. Avens are proven to be tough plants that require minimal maintenance and offer a variety of flower forms and colors. Gardeners looking for something different need look no further than vibrant spring-blooming avens.