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.
With days getting a bit longer, the urge to get outside and “do something” starts to grow. Here are a few tasks to consider tackling this month. But keep in mind, soggy, wet soils compact very easily. Avoid walking or driving on wet soil whenever possible.
Keep outdoor evergreens well-watered and even deciduous plants if they were planted late in the season. Dry roots and drying winds will challenge evergreens to stay hydrated. Check for any deer browsing and net or apply repellent if evergreens are being chewed.
Keep an eye open for perennials that have heaved out of the soil due to freeze thaw cycles and gently push them back in place to prevent roots from drying out.
If you have bird baths, try to keep fresh and unfrozen water in them for not only birds but other animals that need a drink.
On mild days, go outside and clean out your birdhouses for future residents.
Its hard to resist the desire to start garden clean up on those mild days that pop up here or there, but try not to disturb the gardens too much yet (except for maybe pulling out some of the evil Hairy Bittercress). There are valuable critters sleeping in the debris and they need days consistently above 50 F to wake up for the season.
Use downed branches to start or add to a brush pile for the critters that share your property. These are great in far corners away from view and help with habitat. For information on brush piles click here.
If the weather is nasty, there are indoor tasks to do as well.
Dust your indoor house plants. They can photosynthesize much better without a layer of dust on their leaf surface. Be careful not to over water or fertilize. They are not as energetic in the winter, quite like us!
Take some time to peruse catalogs and on-line plant sources. Dreaming about amazing new additions to the garden is half the fun. Before you place those orders, stop to consider and reassess where those plants will go in your landscape and if you will have time to plant/care for them. Unusual items are worth the order but more “common” plants might be purchased at your local nursery in a larger size for the same cost.
Now is a good time to organize your records and get your plant tags ready for spring. If you have records of plant purchases for the previous year, use that for making tags to place when weather is mild or when spring finally arrives.