Plantsmen and plant breeders have been busy developing and selecting compact and small-stature colorful shrubs in the last few years, says Kathy Zuzek, UMN Extension Educator. Some of those cultivars that will grow in our northern gardens are Fire Ball burning bush, Little Lime hydrangea, Northern Accents Sigrid rose, and Oso Happy Petit Pink rose.
Burning bush (Euonymus alatus) is a highlight in our Minnesota fall landscapes where it grows as a large shrub or small tree in landscapes and adds bright red to our fall landscapes when grown in full sun. In partial shade, burning bush provides wonderful combinations of pink and green in fall. "Compactus," a commonly grown cultivar in Minnesota, grows to 6 to 8 feet. Although it rates as hardy to Zone 4 (or hardy to -30 F), it often suffers some stem injury when winter temperatures drop to -25F. Fire Ball burning bush is a plant selected for its superior winter hardiness and tighter branching by Cole Nursery in Ohio. This is really not such a new cultivar as it was selected years ago. But it has been recently rebranded and is finally being widely marketed. Fire Ball's height and width are 5 to 6 feet, and in Michigan where this plant has been tested, no winter injury was seen on stems of Fire Ball during the harsh winters that did injure "Compactus."
Hardy hydrangeas in Minnesota are the panicle hydrangea (Hydrangea paniculata) and the smooth hydrangea (H. arborescens), and many wonderful cultivars have been developed or selected among both species. Limelight panicle hydrangea is a popular 8-foot tall cultivar whose new flowers emerge in tones of soft lime green and ivory and then mature to pink and burgundy in fall.
A new introduction from Spring Meadow Nursery is Little Lime hydrangea with green and ivory flowers on a 3 to 5 foot plant and rated as Zone 3 hardy (hardy to -40F.)
Ninebarks (Physocarpus opulifolius) are large plants that can reach 8 to 10 feet in height and width. Several cultivars have been selected for their gold or red-purple foliage and some of these have more compact growth habits of 5 to 7 feet. The newest and smallest addition to the ninebark collection was bred here in Minnesota by Dr. David Zlesak and is named Little Devil. Little Devil is a upright ninebark that grows to 3 or 4 feet in height and width with smaller burgundy leaves and white-pink flower clusters that pair beautifully with the small plant stature. Little Devil is listed as Zone 3 hardy.
Two new small statured roses are available this year for northern landscapes. The fourth cultivar of the University of Minnesota's Northern Accents collection is Sigrid, with its double red flowers. Like its predecessors, Sigrid is a repeat-flowering polyantha rose with a 3-foot compact dense plant habit, large sprays of 1-inch flowers, and a high level of blackspot tolerance. Sigrid is crown-hardy in Zone 4 hardy.
Oso Happy Petit Pink rose is another Minnesota introduction from Dr. David Zlesak. Petit Pink is a Zone 4 hardy, repeat-flowering miniature rose whose pink and yellow petals add lots of warmth to a landscape. Petit Pink dies back in winter to the crown or within a few inches of the ground and then grows back into a 2.5 foot by 3 foot rounded dense plant.
For more information regarding gardening, you can reach me at Stephanie@starpoint.net