Landscaping With Goldenrods

Goldenrods at Dawes Arboretum

Goldenrods (Solidago spp.) represent about 100 species of perennials that grow ubiquitously along U.S. roadsides, prairies, open woods, and riverbanks. (USDA hardiness zones 4-9). A small number of species are also native in South America and Eurasia. Goldenrods are grown for their bright yellow or golden flowers that form late in the summer. They are easy to grow, and the tiny yellow flowers are a bountiful source of nectar for bees and butterflies, including Monarchs; seeds are eaten by songbirds fall and winter.

Goldenrods grow in almost any soil that is well-drained and in full sun. Removing spent flower clusters will encourage more blooms. Deadhead the old spent flowers to avoid prolific self-seeding. Every 3-4 years, divide plants in spring or fall.

Showy goldenrod (Solidago speciosa) is an eye-catching selection with abundant tiny, bright yellow terminal flower clusters atop stiff, narrow-leaved, reddish stems; 2-3 feet tall starting in mid- to late-summer.

Wreath goldenrod (Solidago caesia), aka blue stem goldenrod grows 1.5- 3 feet tall on arching, glabrous, wiry, greenish-purple stems which are covered with a silvery-white waxy covering (zones 4-8). yellow clusters of tiny flowers  bloom along the purplish stem in early autumn. Lance-shaped, medium green leaves (2-5 inches long) are toothed with sharply pointed tips.

‘Fireworks’ rough-stemmed goldenrod (Solidago rugosa) is probably the most popular variety, 3-4 feet tall clump-forming plant is covered with stiff bright yellow inflorescences starting in early autumn, reminiscent of exploding fireworks. 

‘Golden Fleece’ goldenrod (S. sphacelata ‘Golden  Fleece’)  grows 18 – 24 inches tall and 24-36 inches wide forms showy sprays of golden yellow flowers starting in mid-September into October.. Its heart-shaped leaves are semi-evergreen.

Ultra-dwarf varieties:

·         Little Lemon® (‘Dansolitlem’) - light yellow flowers on ultra-compact (14 inches tall / 18 inches wide plants.

·         ‘Cloth of Gold’- deep yellow flowers on 18-24 inch tall stems.

·         ‘Crown of Rays’ - bright yellow flowers on 2-3 feet tall stems.

No serious insect or disease problems trouble goldenrods and are moderately deer tolerant. If summer weather is unusually wet or planting is too crowded, expect minor disease problems.

Coneflowers

'Showoff' Echinacea at Kingwood Center, Mansfield, OH

Coneflowers (Echinacea spp.) have undergone great improvements over the past quarter century. Varieties are now available in many color shades and plants flower for longer periods. Recently introduced cultivars also grow alot shorter. On the negative side, some hybrid forms have been disappointing, barely surviving 1-2 years in the garden.

For overall dependability, Purple Coneflower (Echinacea purpurea) is my #1 favorite for dependability (USDA hardiness zones 3-8). The species is native to most of the Eastern and Midwestern U.S. They bloom in July, August, and into September, their nectar-filled flowers attract  butterflies and bees, and their winter seed heads provide food for birds and other critters.

Yellow Coneflower (Echinacea paradoxa) is native to the Ozark region in Missouri and Arkansas. The yellow blooming E. paradoxa have been bred with E. purpurea. Flowering starts in June, and puts on a long show even as the petals fade. This species has a small geographic range due to habitat loss.

Pale Purple Coneflower (Echinacea pallida) are native from the central U.S. Petals tend to be long, narrow, and droopy along with washed out lavender color. Leaves and stems are particularly fuzzy. They bloom from June to July and grow in most U.S. gardens under proper care.

Tennessee Coneflower (Echinacea tennesseensis) are native the state, but their habitat has been in decline over the past half century. Only recently has it been removed from the endangered species list. This mid-summer bloomer grows 2 to 2 ½ feet tall.

Coneflowers perform best in full sun and within a low to moderate range of soil fertility. While good soil drainage and watering during prolonged dry spells are good practice. Keep in mind that most coneflowers establish deep taproots and resent constant irrigation and over-feeding. To insure winter survival, coneflowers should be planted before July 1st.

New Hybrid Bleeding Hearts

Dicentra 'Luxuriant' 

Bleeding hearts bloom in April into May (in Tennessee - zones 6 and 7). In cooler northerly locales, flowering may continue into summer.  The bright red, pink or white, heart-shaped, pendant flowers are supported on arching stems.

Bleeding hearts (Dicentra spp.) are truly one of nature’s glorious delights in the spring - early summer garden (USDA hardiness zones 3-9). Old fashion bleeding hearts (D. spectabilis), indigenous to Asia, grow taller and wider compared to their North American counterparts wild bleeding heart (D. exima) and Dutchman's breeches (D. cucullaria).

A number of new cultivars have been released in recent years that are hybrid crosses between D. peregrine (native to Japan) x D. exima (native to eastern North America) x D. formosa (native to Western U.S.). These bleeding heart grow more compact and robust, are longer flowering, exhibit blue-gray foliage, and offer more floral color choices.

Four notable hybrid cultivars include 'Luxuriant' (D. eximia  x D. formosa  - deeply-cut,  grayish-green foliage and cherry red blooms. ‘King of Hearts’ (D. peregrina x D. formosa subsp. oregana x D. eximia) - very compact grower only 9 inches high and 14 inches wide. 'Fire Island' (D. peregrina x D. exima) - white tipped magenta red flowers from late spring into midsummer and 12 inch x 20 inch mound of frosty blue foliage. ‘Valentine’ - a vigorous hybrid form with showy cherry red/white tipped flowers.

New hybrid forms tend to grow more vigorously and are spaced 24-36 inches apart. Good soil drainage is essential for bleeding hearts. Plant in a humus-rich mildly acidic soil along with more hours of sunlight, preferably in the morning. Lightly mulch around plants in a woodland garden. In late winter feed a slow-release fertilizer at the low package rate.

In southern locales hybrid forms generally die back (go dormant) by mid-summer unless regularly irrigated. Crowded clumps should be divided either in very early spring or after flowering.

Spring flowers attract butterflies and hummingbirds. Aphids, slugs and snails occasionally feed on the leaves. Plants are deer and rabbit resistant.

Bleeding hearts are great companions with other woodland plants such as ferns, lungworts (Pulmonaria spp.), brunneras, coral bells (Heuchera), and foam flowers (Tiarella).

Note: in recent times the genus Dicentra has been changed to Lamprocapnos.

Growing Pentas To Attract Pollinating Bees And Butterflies

Want to attract more butterflies to your garden this summer? Pentas (Egyptian starflower) (Pentas lanceolata) is what you should be planting. Pentas are one of the best pollinator-attracting plants around. Flower colors range from red, pale lavender, pink and white. 

Pentas blooms all summer long, even during the hottest weather conditions. The large clusters of star-shaped blooms attract butterflies, bees and an occasional hummingbird. These annual flowers perform well both in garden beds and in large containers. Keep plants deadheaded and remove any spent blooms to encourage constant flowering.

Pentas plants are annuals in most U.S. climates (zone 10 hardy). The overall habit of these plants is neat and compact. If plants get too long and woody, cut them back by one-half and feed them with a water soluble fertilizer such as Miracle-Gro™, Jacks™, or Schultz™. Tall leggy transplants should be tipped back to develop more branching.

Overall, pentas are very easy to maintain. Newer varieties have improved disease resistance and grow shorter, e.g. more compact in habit. Pentas are troubled by few diseases and should be inspected for insects like aphids (in cool springs) and spider mites (dry hot summer periods).

Pentas prefer to be planted in full sun and in moist, well-drained soil. Pentas will dry out in hot summers and should be irrigated weekly during these times.

Leading cultivar series are Graffiti™ and Kaleidoscope™ (compact growers); Butterfly, Starla, and Northern Lights (taller growing).

Vitex 'Shoal Creek'

Chastetree (Vitex agnus-castus) is an 8-10 foot deciduous shrub or 12-15 foot tall small tree (hardiness zone 6-b thru 8). Branching habit is dense and vase-shaped (upright). It blooms over most of the summer, from June thru late August. Its 12-18 inch long blue-violet flower spikes exude a slight herbal fragrance.

‘Shoal Creek’ is a leading cultivar. Cold hardiness appears better than most, although this has yet to be proven. The finger-like compound leaves are covered with pubescent hairs. Summer foliage color is grey-green, with a faint bluish cast more visible in May and June. Its disease resistant foliage and butterfly magnetism rates this vitex in a class on its own. Foliage is highly deer resistant.

Stem die-back may occur in a cold winter, but this fast grower recovers rapidly. Since flowering occurs on new growth, prune off all dead, injured and crowded branches before the start of May. Vitex prefers full sun, but will tolerate part sun. Plant in a loose, well-drained soil and keep adequately watered during the first year. Afterwards, vitex possesses very good drought tolerance.

Try 'Fireworks' Gomphrena in Your Garden

'Fireworks' gomphrena was a sensation in the University of Tennessee Gardens at both the Knoxville and Jackson locations in 2009. Gomphrena (globe amaranth) is a great summer annual that asks for very little care. It is heat, humidity and drought tolerant. Gomphrena hold up to the wind, blooming from day of planting in May (after danger of spring frost has passed) until first hard frost in autumn. No bug or disease touches them.

By fall most gomphrena cultivars grow 18 inches to 2 feet in height and 12-15 inches in width. Add another 12 inches for more the vigorous 'Fireworks'. Can't find 'Fireworks', try another cultivar favorite- 'Strawberry Fields'. Gomphrena attracts large numbers of butterflies and are great as cut and/or dried flowers.

Buy plants at local, independently-owned garden centers. Generally, "big box store" garden centers carry more common summer annuals and not gomphrenas.

Lo and Behold 'Blue Chip' Buddleia is a Winner

photo taken at JC Raulston Arboretum in June 2009

Lo & Behold® ‘Blue Chip’ is a very dwarf butterfly bush (buddleia) for the summer garden. Take advantage of its compact 3 x 4 foot height and width by planting it in the garden or in a container on a sunny patio deck or patio by itself . In large containers mix in shorter growing summer annuals such as trailing petunia, scaevola or alternanthera.

Lo & Behold® ‘Blue Chip’ maintains its clean growing habit all season long. Gardeners with limited space can attract butterflies and hummingbirds to their garden with this colorful buddleia. It produces loads of fragrant blue flowers which bloom continuously. It thrives in the summer heat and humidity and the foliage stays blemish-free.

'Blue Chip' is non-invasive. It's self-cleaning and will bloom from mid-summer to frost without deadheading. Each proceeding spring, you won’t need to drastically prune 'Blue Chip' as you would the larger growing buddleia varieties. Plants are deer resistant and drought tolerant.
‘Blue Chip’ was still blooming in my Southern Appalachian garden in late October .