Shrub Collections

Learn more about the Azalea Trial Garden

This area contains 160 species and 245 cultivars of shrubs hardy to Minnesota's landscape. There are a total of 497 specimens here.

This changing collection represents the best shrubs for our landscape and that are available in local nurseries. A few of them may have been overlooked by the home gardener and occasionally the nursery industry! The plants are We have arranged them in landscape settings to give you an idea of how they might look in your yard.

Look for the five instructional signs covering garden design, planting and maintenance of shrubs. Notice how they change during the course of the year. Which ones would suit your landscape at home? 

Dwarf conifers are some of the most exotic woody plants for the Upper Midwest garden. The term "dwarf" is a loose one, covering woody plants from creeping juniper only a few inches high, to dwarf spruce and pine, which could grow up to 15 feet tall. Some of these conifers have variegations in foliage, colors and leaves. They can add fantastic accents to a small backyard garden or a large-scale rock garden.  We have seven 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 yuccas (Yucca sp.) and prickly pear cactus (Opuntia sp.). The headwaters, pool and granite bridge allows you to walk over water and view them from overhead.

This collection (Hydrangea sp.) contains three species, seven cultivars and a total of 25 hydrangea specimens. Hydrangeas are known for their coarse foliage and giant flower heads.  Though most have white blooms, there are several hardy blue and pink flowering hybrids. To maintain a blue color, add acid fertilizer and aluminum sulphate regularly to the soil mix.

The Hueg Lilac (Syringa sp.) Collection is the Arboretum's oldest.  It was designed by Lee Snyder, Leon Snyder's son, and planted about the time that the Arboretum bought the land.  Here you will see several 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.

There are many shrubs that 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.

The Pea Shrubs (Caragana sp.) are not as widely used as in the past. When massed, their sturdy, hardy, disease resistant strengths make it perfect for wind breaks and shelter belts. Its small yellow to white flowers are not conspicuous but its dense, fine foliage make 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 broad group. They can be low-growing perennials up to mid-sized yellow flowering shrubs. Potentillas are Minnesota hardy and bloom nearly continuously throughout the summer. Consequently they have a tendency to be over used. Several newer hybrids have 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 where we study and evaluate breeding for hardiness and good bloom of the evergreens. The collection has 66 cultivars and hybrids, including cultivars from Scandinavia.  Find this collection at the bottom of the hill along Three-Mile Drive just past the nut collection.

More information coming soon on the spirea collection!

Viburnum (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, because they resist diease and pests well, have good form and foliage and most have reddish fall color. The flowers are generally white and showy. Some 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.) have attracted much attention from breeders in recent years. 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 larger ones up to 8 feet in height.  The Arboretum has 22 cultivars and a total of 59 specimens.