Ruellia humilis
Wild Petunia
Flower description and bloom time
This prairie native has light lavender petunia-like flowers that are 1 ½ inches in diameter. Wild petunia blooms sporadically from June through October; flowers usually fall off cleanly so deadheading is unnecessary.
Foliage interest—color / texture
Wild petunia’s fuzzy green foliage remains ornamental throughout the entire season.
Habit and growth rate observations
The low sprawling growth habit, 6 to 8 inches tall, will trail across or climb up and over depending on the neighboring plants.
Site preference—soil and light
The wild petunia enjoys full sun and moderate soil types; however, it will tolerate dry soils after becoming established.
Successes and possible drawbacks—how to overcome them
The trailing habit and tendency to self-seed can be a deterrent for some gardeners. When planted in adverse conditions like outcropping in a rock garden, the trailing habit can be a used to soften the edges. Also works well as a groundcover or in combination with other aggressive perennials.
Notes from growers / retailers
Ruellia is slow growing and unattractive in the container in spring. By midsummer the plant is fuller but still somewhat leggy. Best results in containers are achieved if the plants are kept on the drier side. Wild petunia is pest-free in containers and in the garden.
Best combinations
Wild petunia is best planted with drought tolerant plants such as prairie dropseed [Sporobolus], sedum, and daylilies.
Parting SHOT” —the overall evaluation results were Fair **
Due to its tendency to self-seed everywhere, it was given a rating of Fair in the overall appearance category. Not a good plant for the typical backyard garden, but a good pick for a tough site; e.g. a parking median bed. While limited in its applications, Ruellia humilis does fill a need in some gardens. Its trailing habit, drought tolerance and soft violet, long-blooming flowers make it appropriate for the rock garden or the drought-resistant prairie. Its lengthy bloom time will add color to your garden for much of the summer into fall!
Evaluated 2004-2007
Sanguisorba ‘Red Thunder’
Red Thunder Burnet
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Flower description / bloom time
Dozens of burgundy-red, knob-shaped flower heads on wand-like stems, to 30 inches tall; blooms in late July through September.
Foliage interest—color/texture
The foliage is pinnately compound. Each medium green leaflet is 2 inches long, lightly textured and toothed. However, when the Japanese beetles start eating holes in the leaves, they become brown and unsightly.
Habit and growth rate observations
Generally, plants took a couple of years to establish, and were described as thin and ‘wimpy’ in first year but ranged from 36 to 46 inches tall and 24 inches wide in the third year. Plant habits were adversely affected by Japanese beetle damage, rabbit browsing, and wind damage.
Site preference—soil & light
‘Red Thunder’ grows best in full sun to light shade in average well-drained soil and needs extra water during periods of drought.
Successes and possible drawbacks—how to overcome them
The biggest drawback to this plant is its attractiveness to critters like Japanese beetles and rabbits. It is one of the first plants in the garden that Japanese beetles go to when it starts to bloom. This is a nice filler plant with hundreds of tiny button size flowers held above the foliage.
Notes from growers/retailers
The flowers are not showy enough to attract the average garden center buyer.
Best combinations
Rudbeckia fulgida ‘Goldsturm’, Hemerocallis (pink or gold varieties), Allium senescens ssp/ montanum ‘Summer Beauty’, Miscanthus sinensis ‘Morning Light’, Geranium ‘Rozanne’.
Parting “SHOT”— the overall evaluation results were Fair **
‘Red Thunder’ can be a lot of work and probably best for an experienced gardener or collector. It can be useful as a filler plant where its lacy foliage and elongated button flowers can be used to highlight other bolder flowered and foliage plants. Its downfall is that it is a major food source for Japanese beetles and rabbits.
Evaluated 2005-2008
Silene caroliniana var. wherryi ‘Short and Sweet’
Silene ‘Short and Sweet’
Silene caroliniana can be found in rocky, calcareous woods and outcrops from New Hampshire to Ohio and south to Missouri and Alabama. It is not found in Illinois.
Flower Description and Bloom Time
Pink round flowers with wedge-shaped petals less than an inch wide appear from late May through early June (about a two-week bloom period). A cultivar of a native, ‘Short and Sweet’ has flowers that attract nectar-seeking insects and butterflies. The sticky flowering stems give this plant the common name “catchfly.”
Foliage Interest — Color and Texture
Tufts of narrow, lance-shaped green basal leaves (up to 4 inches long) with smaller paired stem leaves.
Habit and Growth Rate Observations
During the first year of the trial, plants grew anywhere from 3 to 6 inches tall to 6 to 10 inches wide.
Site Preference — Soil and Light
This silene is often found in dry, rocky or sandy forests, as well as barrens and areas with limestone outcrops. All of these habitats indicate the plant’s need for good drainage so that it does not remain wet for any extended period of time. Grow in bright shade to full sun.
Successes and Possible Drawbacks
All the plants died by the third year of the evaluations.
Notes from Growers/Retailer
Hardy in Zones 4 to 7. Touted as a native plant substitute for Dianthus because of the similar appearance.
Good Combinations
If you decide to try this plant, combine it with native sedum (Sedum ternatum), columbine (Aquilegia canadensis) and native violets.
Parting “SHOT” — The overall evaluation results were Poor. 1/2 star
This plant was evaluated from 2011-2014 at four sites in Chicago’s western suburbs and the North Shore. Although this cultivar is described as long blooming, compact and easy to grow, all 12 plants in evaluators’ gardens were dead by the end of the trial.
Symphyotrichum oblongifolius ‘October Skies’
(formerly Aster oblongifolius ‘October Skies’) Aromatic Aster
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Flower description / bloom time
October Skies is a selection of a native to the northeast and has masses of small [about one inch] soft lavender-blue daisy-like flowers with yellow centers that bloom late August into October.
Foliage interest / color and texture
The foliage is narrow creating a fine texture. The gray-green color is pleasing all summer and no powdery mildew was reported. Evaluators rated the foliage as good and praised it for its lack of disease issues. It is also aromatic when touched. In all but one site, this aster was not browsed by deer or rabbits.
Habit and growth rate observations
October Skies has a medium growth rate and is supposed to achieve mounds under two feet. But in some garden sites the plants became large masses approximately 30″ x 45″ – perhaps due to planting in overly rich soil [see site preference]. The habit tends to be a little floppy or sprawling by the end of the season. All plants survived except in one location where deer decimated the plants and they died out by year two.
Site preference / soil and light
Aromatic aster does best in full sun, with dry to average soils. Those grown in part shade or fertile, moist soils were more sprawling.
Successes and possible drawbacks—how to overcome them
The floppy late-season habit is a definite drawback. This could potentially be overcome by good pruning practices earlier in the season. Cutting the whole plant back by one-half around July 1 is suggested. Also, some evaluators rated this plant less floriferous and more sprawling by the third year. Other evaluators had better success with drier soil. Also, the blue flowers late in the season were judged a plus.
Notes from growers / retailers
Plugs were reported to finish in 4 to 5 weeks after rooting. To promote more compact growth, plants should be pruned or pinched by one half. Most growers reported that plants did over-winter in production but one grower did not have this success. Another grower reported that the plant was a prolific ‘re-seeder’ —this was not reported by those who trialed the plant.
Best combinations
October Skies looks great with ornamental grasses and other late-season, sun perennials and also looks good in naturalized settings.
Parting SHOT”—the overall evaluation results were Good ***
While Symphyotrichum oblongifolium October Skies has its drawbacks, it still received a good overall rating for the profusion of flowers produced in fall. So with a little foreknowledge of soil and light preferences, a gardener should have success using this aster.
Evaluated 2003-2006
Veronica longifolia ‘Eveline’
Eveline Speedwell
Eveline speedwell blooms mid to late summer with some re-bloom in September. The flowers are pink-purple on a tapering four-inch spike. Repeat bloom is more consistent when spent flowers are deadheaded.
Foliage interest – color/texture
Dark green, disease-resistant foliage stays shiny and clean late into the season. There is no significant fall color.
Habit and growth rate observations
Plants grow 24 inches tall by 15 to 18 inches wide. Very upright habit does not flop.
Site preference – soil & light
Grow in full sun to part shade in average garden soils. Eveline is also very drought tolerant.
Successes and possible drawbacks – how to overcome them
Eveline is an easy to care for perennial that attracts butterflies and hummingbirds.
Notes from growers/retailers
Eveline is good in containers and has a long shelf life in the nursery. It roots easily from cuttings. From a #30 cell plug, it takes eight weeks to finish.
Good combinations
Calamintha nepeta ssp. nepeta, Carex sprengelii, Sesleria autumnalis, Achillea varieties.
Parting SHOT – the overall evaluation results were Excellent ****
Eveline speedwell was recommended by all evaluators because of the long bloom time and its disease resistance.
Evaluated 2003-2006
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Veronica ‘Purpleicious’
Flower Description and Bloom Time
Flowers were given high marks for repeat bloom. Evaluators characterized its flower color as a purple-pink, jewel-toned violet and rich pink-violet. Peak bloom took place in June-July, but some flowers were still present in September.
Foliage Interest — Color and Texture
Medium-textured, glossy dark green foliage with little leaf spot.
Habit and Growth Rate Observations
Most evaluators rated the plant’s habit and growth rate as ‘Good.’ Plants typically were 20 inches tall to 12 inches wide.
Site Preference — Soil and Light
Full sun, rich, well-drained soil with a medium amount of moisture.
Successes and Possible Drawbacks
Deadheading spent flowers will prolong flowering into late summer. Although leaf spot is common on some Veronica cultivars, this one showed little to some leaf spot. Supplemental watering was provided during periods of drought. Root rot may occur in wet, poorly drained soils.
Notes from Growers/Retailers
N/A
Good Combinations
Veronica ‘Purpleicious’ can be used in rock gardens, cottage gardens, perennial borders and as a pollinator-friendly plant. Grow with other sun-loving perennials such as Echinacea, Rudbeckia, Monarda, butterfly milkweed (Asclepias tuberosa) and Sedum where the Veronica blossoms can provide a vertical contrast.
Parting “SHOT” — The overall evaluation results were Good***
Seven evaluators trialed this plant primarily in Chicago’s western suburbs. Some of the positive comments were “good flower color, long bloom time and little leaf spot” and “a much-needed, compact spiky plant.” Others noted that the flower color was similar to Veronica ‘Eveline,’ but that the flowers were fuller and more robust on ‘Purpleicious.’
Evaluated 2007-2010
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Viola ‘Purple Showers’
Purple Showers Viola
Flower Description and Bloom Time
Lightly fragrant, deep purple-violet flowers appear in spring and then sporadically throughout the season, providing a soft show of color. The flowers fade to lavender. Although flowering in one trial garden (full sun and well-drained soil) was prolific, the May flowering was sporadic in the other gardens.
Foliage Interest — Color and Texture
Evaluators described foliage as nice, with crenellated leaves of medium to deep green. In most of the evaluation gardens, foliage remained green and disease-free through fall.
Habit and Growth Rate Observations
Plants ranged from 3 to 5 inches tall and 5 to 6 inches wide. Some plants that got leggy during the first growing season were cut back, which allowed for a second flush of flowers. Plants were slow to fill in or weak in most of the evaluation sites.
Site Preference — Soil and Light
While some garden sites suggest moist sites for this plant, others tout it as suitable for alpine/rock gardens, which require dry soil. Full sun to partial shade.
Successes and Possible Drawbacks
According to one evaluator, “If used as an annual, this plant would not disappoint.” In another trial garden, the evaluator stated, “This has been a great shade plant, filling in, gradually spreading and I would definitely recommend it.” Others who trialed the plant had problems with rabbits, poor drainage or poor winter conditions that led to the plants’ decline. Watch for slugs. Cut back if the plant becomes leggy.
Notes from Growers/Retailers
Keep dry, cut back halfway through growing season to prevent plant from becoming leggy. Use slug traps if needed.
Good Combinations
Use as a shade garden companion to Hosta, Astilbe, dwarf daffodils, dwarf Aruncus and ferns.
Parting “SHOT” – the overall evaluation results were
fair. **
Only three of the 24 plants survived the 3-year trial period. In one garden, plants formed a petite mass from the original three plants. Those plants had been sited in an area with good drainage, which appears to be key for their survival.
Evaluated 2007-2010
