The azalea collection (Rhododendron sp.) is a research collection and as such not all plants are labeled. The species, cultivars and un-named hybrids are all part of the Horticultural Research Center's azalea breeding project. To date 13 hardy azaleas (the Northern Lights series) have been released from this program, creating a wide variety of colors hardy in Minnesota. Several more hardy azaleas can be found throughout the gardens.
The Northern Lights azaleas are the Arboretum's signature plant and are found throughout the grounds. Introductions include, Golden Lights, White Lights, Pink Lights, Rosy Lights, Northern Lights, Northern Hi-Lights, Lemon Lights, Mandarin Lights, Tri-Lights, Candy Lights, Lilac Lights, Orchid Lights and Spicy Lights.
Most are available in local nurseries and more hybrids are on the way. You can't beat the rhododendron genus for fabulous flowers and fragrance!
Bailey Shrub Walk
The Bailey Shrub Walk contains 160 species and 245 cultivars of shrubs hardy to Minnesota's landscape. There are a total of 497 specimens in the collection.
This changing collection represents the best shrubs for our landscape and ones that are available in local nurseries. However, a few are shrubs the Arboretum feels are overlooked by the home gardener and occasionally the nursery industry! The plants are arranged in landscape settings to give you an idea of what they might look like in your yard.
Among the plantings are five instructional signs covering garden design, planting and maintenance of shrubs. Take a close look at all the shrubs during the course of the year to determine those you like the best and ones you feel will fit your landscape the best.
Dwarf Conifer Collection
Dwarf conifers are some of the most exotic woody plants for the Upper Midwest garden. The term dwarf is a loose term and covers woody plants from creeping juniper, only a few inches high, to dwarf spruce and pine which could be up to 15' or more tall. Obviously you need to select your ‘dwarf' carefully! Some of the conifers have various variegations in foliage and a variety of colors of cones and leaves. They can add fantastic accents to a small yard garden or a large scale rock garden. We have 7 genera, 21 species and a total of 152 dwarf conifer specimens in this garden.
The waterfall headwaters has a variety of plantings surrounding it including yucca's (Yucca sp.) and prickly pear cactus (Opuntia sp.). The headwaters, pool and granite bridge allows visitors to literally "walk over water."
The hydrangea collection (Hydrangea sp.) contains 3 species, 7 cultivars and a total of 25 specimens. Hydrangeas are known for their coarse foliage and giant flower heads. Though mostly white, there are now at least a couple of blue and pink flowering hybrids that are hardy. To maintain a blue color, acid fertilizer and aluminum sulphate must be added regularly to the soil mix.
The Hueg Lilac (Syringa sp.) Collection is the Arboretum's oldest collection. It was designed by Lee Snyder, Leon Snyder's son, and planted almost before the land was purchased. The collection contains several different types of lilacs and their cultivars, including common, French hybrids, Chinese, Preston, Peking, and Japanese. There are 26 species, 123 cultivars and a total of 179 specimens.
At the top of the hill is the Anne Blackman Garden and lilac information kiosk. The kiosk gives information on lilac types and cultivation.
Lilacs do well in Minnesota but many get mildew by summer's end and can be unsightly. They can always be justified, however, by their fragrant and beautifully spectacular blooms in May and June.
Miscellaneous Shrub Collection
There are many shrubs which are hardy in Minnesota but few have enough species or cultivars to merit a full collection. These assorted groups contain many barberry, tamarisk, dogwood, cotoneaster and more. Many of the new and untested shrubs are first trialed in this collection. Spending some time perusing these beds is well worth it when searching for the right shrub for your yard. This collections contains 34 genera, 111 species and cultivars.
Pea Shrub Collection
The Pea Shrubs (Caragana sp.) are not as widely used as in the past when their sturdy, hardy, disease resistant strengths made them perfect for wind breaks and shelterbelts. Its small yellow to white flowers are not terribly conspicuous but it does have a dense fine foliage making it good for hedges. It's a thorny plant so watch out. We have 10 species and 3 cultivars and a total of 35 specimens.
The potentillas (Potentilla sp.) are a group of very low growing perennials to mid sized yellow flower shrubs which are very hardy and bloom nearly continuously throughout the summer. Consequently they have a tendency to be over used. Recently several new hybrids have been released with larger flowers (1-2 inches across) and new colors, white, gold, red. We have 42 specimens in our collection.
The Rhododendron Garden contains the Arboretum’s evergreen rhododendron collection (Rhododendron sp.). It is also the scientific study area for our evaluation and breeding for hardiness and good bloom of the evergreens. The collection has 66 cultivars and hybrids, including cultivars from Scandinavia. The collection is located at the bottom of the hill along Three-Mile Drive just past the nut collection.
The viburnums (Viburnum sp.) is a large genus with plants native to North and South America, Europe and Asia. Nearly all the species and cultivars are good landscape plants as they are relatively disease and pest free, have good form and foliage and generally have reddish fall color. The flowers are generally white and showy. Some of the viburnums do get mildew by late summer, especially V. prunifolium (blackhaw) and V. lentago (nannyberry). A few viburnums have fragrant flowers but those are generally not hardy in Minnesota. We have 13 species, and 20 cultivars and a total of 56 specimens.
The weigelas (Weigela sp.) are a shrub which has gathered much attention from breeders over the past ten years or so. There are a wide variety of flower colors in the pink and red range and various size plants from dwarfs at 2 feet tall to eight foot shrubs. The Arboretum has 22 cultivars and a total of 59 specimens.