Welcome back old friend! The ubiquitous annual that all shade gardeners loved is back and ready to create season-long color. Impatiens are what we are discussing.
Impatiens walleriana were attacked by Impatiens Downy Mildew (IDM). This disease caused defoliation and eventual death of impatiens well before the growing season ended. The disease was difficult to control; and airborne and overwintering soil spores re-infected new plants. This disease essentially ended sales of the once common annual.
Other annuals came to the shade gardener’s rescue; Begonia, Torenia, Coleus, New Guinea impatiens, and Caladiums but some things can never be duplicated.
Through a collaboration of plant breeders and extensive plant trials in Washington State, Michigan, Colorado, Texas, Minnesota, England, Australia, South Africa and here in Pennsylvania at Penn State, two varieties were deemed to be worthy and will be introduced for sale in 2020.
Beacon and Imara are the two brand names these new impatiens will be sold under. The Penn State trials that were overseen by Sinclair Adam revealed Beacon to be slightly better in Pennsylvania gardens. Both Beacon and Imara are hardy and vigorous for your garden but with any plant, conditions may favor one variety over the other. Color variety is not as extensive as previously but I am sure with time we will have many more to choose from.
Keep an eye out this spring for the reintroduction of this hardworking, floriferous, easy care annual.
Are you familiar with the plant commonly known as “Himalayan Sweet Box” (Sarcococca hookeriana var. humilis)? This is one of those plants I dearly love, especially this time of the year.
Sweet Box is actually a shrub, but it is very low growing and spreads, creating a ground cover. No worries about a horticultural invasion. It spreads slowly – you’ll actually wish it spread faster than it does.
It does need some shade – especially during hot afternoons. If it gets too much sun in winter, the leaf tips might brown a bit. But once it is established, it can tolerate dry, shady soils – even those under established trees. It looks fresh, green and tidy all season.
The common name “Sweet Box” is very fitting. It maintains it shiny green leaves like a boxwood (although they are larger and pointy), but it gets small, intensely fragrant flowers in very early spring (in my garden – about the same time as the snow crocus). Brought inside, the flowers can subtly perfume the entire room.
One caution though, Sarcococca hookeriana is susceptible to boxwood blight so if you know you have boxwood blight on your property this may not be the best plant choice.
The selections are made by a committee of growers, nursery owners, landscape designers and other horticulturalists who have had the opportunity to observe the plants over time. They are chosen for their hardiness, pest and disease resistance, ease of growing and maintenance – as well as appearance of course.
This year, they have singled out one tree, 2 shrubs and 3 herbaceous perennials.
The tree is Carpinus caroliniana, commonly known as American Hornbeam but sometimes called Ironwood or Musclewood. It is an understory tree so its smaller size can be useful in home landscapes. It is slow growing to about 20-30 feet and has orange- yellow fall foliage. This tree is native to the mid-Atlantic.
One of the chosen shrubs is Aronia melanocarpa ‘Viking’, also known as Black Chokeberry. This native shrub has fragrant white flowers in spring that turn into glossy black berries in late summer. The berries are edible (although astringent) and can be cooked into pies and jam – or left as a food source for birds. The glossy leaves have good red fall color. ‘Viking’ is a cultivar selected for greater fruit production. This shrub grows 3-6 feet tall and wide. It can tolerate part shade, but flowering and fruiting are best in full sun.
The second shrub is Hydrangea arborescens ‘Haas’ Halo’, a cultivar of our native Smooth Hydrangea. This shrub has large lacecap flowers with sturdy stems that don’t droop after a rain. The lacecaps can be as much as 14 inches in diameter and are sturdy enough to provide winter interest. The flower heads include both showy, sterile flowerets and fertile flowers so they provide more pollen and nectar for insects than the more common ‘Annabelle’ hydrangea. Haas’ Halo also appears to be more drought tolerant (once established) than ‘Annabelle’. This shrub grows 3-5 feet tall and wide in part to full sun.
Coreopsis verticillata ‘Zagreb’ is a compact herbaceous perennial with a light, airy texture. The bright yellow flowers cover the plant from early through mid-summer, with a re-bloom in fall if the plant is cut back to half after flowering slows. ‘Zagreb’ is useful for the front of a border or in pots. It can tolerate poor soils and drought. It does need good soil drainage to prevent crown rot. This perennial is compact (12-18 inches tall and wide), long flowering and long lived.
The second perennial selected is Geranium X cantabrigiense ‘Biokovo’, commonly known as Cranesbill Geranium due to the shape of the seed pods. This plant is low growing and compact, about 6-12 inches tall. It flowers in spring with white flowers tinged slightly with pink. Although somewhat slow growing, it can create a groundcover over time. It grows best in full sun to part shade. While it can tolerate some drought, it may go dormant in late summer in dry conditions. It performs and spreads better in consistently moist, well drained soils.
Although technically a woody sub-shrub, the last selection chosen is usually grown as an herbaceous perennial. Perovskia atriplicifolia ‘Little Spire’ (commonly known as Russian Sage) is a compact selection growing to about 2 feet tall versus 4 feet tall for the species. ‘Little Spire’ grows best in full sun and medium to dry soil moisture. It is drought tolerant, deer resistant and has attractive silvery foliage. The spires of blue to violet flowers bloom for a long period over the summer.
Amsonia hubrichtii has the common name Bluestar or Threadleaf
Bluestar. It is a hardy, long-lived perennial native to Arkansas, Oklahoma and
This Amsonia has lovely, feathery foliage that adds a unique,
billowy texture to the garden. It blooms in spring with light blue, star-like
flowers – but this plant really shines in the fall with brilliant golden-yellow
Amsonia hubrichtii is easy to grow in average, well-drained
soil . With time it can grow quite large, 3-4 feet tall and wide with a shrub-like
appearance. This perennial starts slow
and may need a couple years to fill out but once established it is hardy, dependable
and rarely needs division. A polite grower, it does not spread by rhizomes and
is not known to aggressively self-seed. Amsonia hubrichtii is deer and rabbit
resistant and has no serious pests or diseases.
The flowering and fall color is best in full sun, but it
will tolerate some shade. If grown in
too much shade or very rich soil, its habit will be open and floppy. Cutting it
back about 6 inches after blooming will help prevent flopping.
Rudbeckia laciniata is commonly known as cut leaf coneflower or green headed coneflower. It is a stately native perennial that can reach 9 feet tall under the right conditions but generally grows 5-7 feet tall. Its preferred location is full to part sun in moist soil. It naturally occurs in moist woodland clearings or along stream beds. It is adaptable to average garden soil, but may wilt during periods of drought without supplemental water.
Like many plants, there are both pros and cons to adding Rudbeckia
laciniata to your garden.
On the positive side, this rudbeckia provides plenty of
sunny flowers and has a long 2 month bloom time – July through September. The size and bright coloration of this plant creates
a strong accent in the garden at a time when some other perennials are starting
The flowers are attractive to bees (both native and domesticated) and butterflies, providing a late season nectar source. They have attractive seed heads and the flower seeds provide food for finches in the fall. This coneflower is generally pest and disease resistant and can handle hot, humid summer weather. It is considered deer and rabbit resistant.
Because of its tolerance for moist soil and periodic
flooding, it is a good plant for flood prone areas or rain gardens. Given
space, it can create a (very tall!) groundcover. The root structure provides
good erosion control.
However (here come the cons), in moist sunny areas this
coneflower can spread somewhat aggressively by underground rhizomes. Plants
should be edged or divided in spring to control the spread.
In fertile soils, more shade or windy areas the plants will
probably need staking to keep it upright.
While the plants will probably survive drought, the lower
leaves will droop and brown. Drought stress can occasionally result in powdery
If you can give this plant a bit of moisture and some room
to grow, it might be a great addition to a pollinator friendly landscape.
Echinacea purpurea has the common name Purple cone
flower. It is a lovely herbaceous
perennial that is native to eastern North America. Its showy blossoms usually
appear in late June to early July and can rebloom through August. The blooms are
very attractive to bees and butterflies making Echinacea a great addition to a
pollinator friendly garden. Gold finches
will also visit the flower heads as they ripen to eat the seeds.
Echinacea grows best in full sun, but will take some shade.
It requires well drained soil and is tolerant of drought and poor soil. It grows
2 to 5 feet tall depending on the cultivar and for the most part is self-supporting,
but may need some support if grown in rich soil or too much shade.
Echinacea generally will continue to bloom whether spent
blossoms are removed or not, but removing spent blossoms early in the season
may make the plant look more tidy. Consider leaving some spent blossom seed heads
over the winter as a food source for birds, but be prepared for some self-seeding
around the base of the plant. I consider
this a bonus, and simply move the volunteer seedlings where I want them in the
spring. Echinacea is also used as an herbal supplement to boost the immune
While called purple coneflower, the common version is more
of a pinkish-purple and it has been hybridized into a variety of different
colors including white, yellow, orange, red and even bi-colors. Some varieties
are quite fragrant.
There are also coneflowers that have been hybridized with
double or triple the petals to create a “pom-pom” effect, but note that these
doubles and triples are not useful to pollinators because the hybridization
process eliminates nectar sources. These
hybrids are also mainly sterile, so they do not provide seeds for birds.
Echinacea can be susceptible Aster Yellows. This is a disease
caused by infection by a microorganism called a phytoplasma. The infected plant’s
flowers will remain green and the cones will be distorted with leaf like
projections. The disease can be spread from an infected
plant to a healthy one by leafhopper insects as they feed on different plants
so it is important to remove any infected plants you find. There is no cure for
Echinacea are sometimes bothered by Japanese beetle which
chew the flower petals but they usually out-grow “beetle season” and continue
Want a little more information on Echinacea? Here are some