Chamaecyparis pisifera ‘Golden Mop’In September 2007, I arrived at the Chicago Botanic Garden as the newly hired curator of woody plants. My first big project was to oversee some aspects of the Dwarf Conifer Garden renovation, which was opened to the public in 1988. Due to overgrown plants, unstable paths and a less-than-desirable entrance, this garden was due for a makeover.
To be honest, my knowledge of dwarf conifers was rather limited when this work began. And still today when I speak with conifer enthusiasts, namely Chicago area nurseryman Rich Eyre, owner of Rich’s Foxwillow Pines, I concede that I still have a lot to learn. My involvement with this project, and now having had two years to observe, study and enjoy the finished product, I have developed a deeper appreciation for dwarf conifers and their presence in the landscape.
Our Dwarf Conifer Garden includes a wide range of specimens, some of which do not fall into the dwarf category as defined by The American Conifer Society. It is important to note that dwarf is a specific category based on growth rate and size at 10 years. In this article and in our garden, dwarf conifer includes slower-growing or unusual forms of gymnosperms: cone-bearing plant species (e.g. pines, spruce and firs) and their close relatives that do not produce cones or true flowers and fruits (e.g. ginkgos and yews).
Today with more than 150 different varieties and 600 individual specimens, the Dwarf Conifer Garden offers many horticultural highlights. Living sculptures in every shade of green imaginable, blues, yellows and in the winter hues of maroon and bronze greet visitors at every turn.
Correct conifers
The diversity in size, form, texture and color makes conifers a suitable addition for any garden. Proper selection is important. Fortunately, the wide selection of commercially available varieties provides choices for gardeners in all regions, regardless of garden size or style.
To have success with dwarf conifers, it is essential to consider minimum and maximum temperatures, rainfall, soil structure and moisture levels. Dwarf conifers – and conifers in general – have a reputation of not being widely adaptive to various landscape conditions. This is true for some species, and with a few exceptions, poorly drained soils and deep shade should be avoided.
Most conifers thrive in well-drained, slightly acidic soils, but there are options for poorly drained soils such as Taxodium (bald cypress), Larix (larch) or Thuja (arborvitae), which are predisposed to such conditions. Conversely, dry alkaline soils are just fine for some Juniperus (junipers) and Cupressus (cypress).
Another important consideration is the amount of sunlight the site receives. Most conifer species prefer and even require full sun. This is especially true for Picea (spruce) and Pinus (pine). If the site is shady, there are still suitable options. Both Tsuga (hemlocks) and Taxus (yews) are quite tolerant of shady sites but good drainage is essential.
And now for the fun part – choosing the endless form, size and color combinations. It is important to consult reliable references for growth rate and size. Dwarf conifers may be slower-growing, but they do grow and many do not respond well to heavy pruning. Some cultivars have more normal growth rates but differ in foliage color or habit. Taking time to consider the habit or foliage color may yield the desired effect.
Vertical spaces. If the site has generous vertical space but limited horizontal space, consider an interesting fastigiate or columnar form.
Fastigate forms can have a significant presence in the garden while occupying a small footprint. Picea abies ‘Cupressina’ (Cupressina Norwary spruce) is a choice in these instances, and its adaptability makes it a great choice for urban landscapes. Beware, this plant is not a dwarf and falls into the “large” category. At 10 years it can reach 15 feet in height, but maintains a narrow upright habit.
Another selection for vertical spaces is Chamaecyparis nootkatensis ‘Green Arrow.’ Green Arrow Nootka false cypress is a graceful fastigiate form that it is very narrow with pendulous branches that develop a skirt at the base of the tree. This has a wonderful form and remains green in the winter months.
Horizontal spaces
If a horizontal effect is desired, there are numerous selections of Juniperus hortizontalis that are suitable for the most challenging of landscape conditions. Creeping juniper is one of the most commonly planted evergreen groundcovers in the United States. This species and its selections are very adaptable to sandy and rocky soils and to hot, dry locations. Selections of blue and green foliage are plentiful, but if the site could use a splash of bright color, Juniperus hortizontalis ‘Mother Lode’ will do the trick. This bright, golden yellow sport of ‘Wiltonii’ has a very flat, low-growing habit and the bright yellow foliage turns yellow-orange tinged with plum in the winter.
Another option with a little more subtle color is Juniperus virginiana ‘Grey Owl.’ Grey Owl eastern red cedar has been around for decades, yet it’s still not common in gardens. The foliage is a soft silvery gray, and being a female clone it can set abundant cones. The low-growing, spreading habit, pleasing foliage color, and adaptability to challenging landscape conditions keep this selection on my list despite dated introduction.
Miniatures
If both horizontal and vertical space is limited, the miniature group has many exciting options. This group includes the little bowling ball and diminutive Christmas tree forms.
Picea omorika ‘Guenter’ (Guenter Siberian spruce) is one of my favorites in the Dwarf Conifer Garden. The needles are dark green above but silver below. The overall effect is subtle but delightful upon closer inspection. Pinus parviflora ‘Hagoromo’ (Hagoromo Japanese white pine) is also a true miniature and noteworthy, as there are very few miniature pines. Its globose habit and short silvery-blue needles make it an excellent specimen for rock gardens, a planter or landscapes with limited space. A deciduous member in this group includes Larix decidua ‘Darling Susie.’
Give them a try
If proper selection is made, dwarf conifers are low maintenance and provide year-round enjoyment in the garden. Ornamental grasses, landscape roses and Japanese maples make great companion plants. Consider joining the American Conifer Society to learn more about this fascinating group of plants, and visit a conifer or dwarf conifer collection at a botanic garden or arboretum in your area. And most importantly, have fun and enjoy the artistic elements these plants bring to the garden.
Andrew Bell is the curator of woody plants at the Chicago Botanic Garden. Send him your conifer questions at abell@chicagobotanic.org.
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