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Small Evergreen Conifers for Winter Gardening

 

Kohout’s Ice Breaker Korean fir has beautiful silvery and blue-green foliage that stands out in winter gardens.

I grow “miniature” or “dwarf” plants with caution*. Living and gardening in the Pacific Northwest, I have found that plants seem to grow larger than many of the plant tags indicate. I have had many experiences where plants get larger than the literature states and many gardening friends tell me that they have had the same experience. Perhaps it is our generally mild weather, rich soils, and regular rain that make for some nearly ideal growing conditions. (Sometimes, I tell myself that the plant does not know what the tag says!) So, growing guidelines can be helpful, and lists of truly tiny plants, in this case, evergreen conifers, useful.

Miniature and Dwarf Conifers Defined

Fortunately, the American Conifer Society has established size categories for conifers that attempt to address the continuous growth of supposed miniatures. While it is not perfect, it is a step in the right direction. The four categories are based on approximate growth per year and include:

  1. Miniature conifers: less than 1 inch
  2. Dwarf conifers: 1-6 inches
  3. Intermediate conifers: 6-12 inches
  4. Large conifers: more than 12 inches.

Of course, the region, climate, and culture will also play a factor in growth. Sometimes home gardeners have the opinion that a dwarf conifer will grow to ten-year dimensions and then stop growing. This is NOT always the case. Woody plants, including dwarf conifers, will continue to grow for the life of the plant–some more than others.

The Best Miniature and Dwarf Evergreens

Chamaecyparis obtusa ‘Hage’ is a truly tiny specimen plant that grows well in containers or rock gardens.

Recently, I visited the gardens of several different friends that grow small evergreens, and here are some truly slow growers that are recommended by the experts. (In my garden, I do not have many dwarf or miniature evergreens. Some that I have had, grew more than I had expected, and I gave them away.)

Miniature Korean fir (Abies koreana ‘Kohout’s Ice Breaker’, Zones 5-8) offers brilliant silver and blue-green foliage throughout the year. This grows in a globose or rounded habit. The foliage has curled needles that show off the silvery-white undersides. Growth is 1-3 inches per year which makes this ideal for small gardens or rockeries. It was awarded the Award of Garden Merit from the Royal Horticultural Society, and in 2014 it was the American Conifer Society’s Conifer of the Year.

Dwarf Columnar Common Juniper (Juniperus communis ‘Compressa’, Zones 4-9) is a narrow, upright, evergreen shrub with foliage that is tightly packed with blue-green needles that are prickly to the touch. The foliage tends to turn to a copper-bronze shade in the winter. It can reach 1-5 feet after ten years and is another Award of Garden Merit winner.

Juniperus communis ‘Compressa’ has a neat, upright habit.

Miniature Hinoki False Cypress (Chamaecyparis obtusa ‘Hage’, Zones 5-9) is a compact pyramidal selection of Hinoki cypress. This foliage also turns bronze-ish in the winter in cold climates. After ten years, it might be about 16 inches tall.

Dwarf Black Spruce (Picea mariana ‘Nana’, Zones 2-8) has needles that are silver-blue-gray and very small that grow from thin branches that stay distinctive throughout their growth. As it grows, it develops a dense round habit, and in ten years it might reach 18 inches tall.

Dwarf Mugo Pine (Pinus mugo ‘Jakobsen’, Zones 2-8) is a clump-forming mugo pine with somewhat irregular branching. Specimens can look almost like bonsai. The needles are very dark green and held tightly together. It can reach 1-4.5 feet after ten years.

Dwarf Cedar of Lebanon (Cedrus libani ‘Hedgehog’, Zones 6-9) has very dark green foliage and forms a dense mound. The needles are prickly and can give the impression of a hedgehog. Expect it to reach 1-4.5 feet after ten years.

Whipcord is a stylish evergreen for small spaces.

Dwarf Western Red Cedar (Thuja plicata ‘Whipcord’, Zones 5-8) is one that I have in my garden, and I love it. I actually have two plants, and both are in matching urn-shaped containers. A description I once read about it said that it, “looks like a firework of stringy foliage”. That is a good description because the green branchlets radiate in all directions. It is low and mounding. After ten years it can reach 1-5 feet.

The selection of small growing evergreens is vast, so it is easy to begin to start collecting them. For those with small-space gardens or a deck, patio, or balcony, many of these make ideal potted plants that look good all year long.

*Writer’s Note: For the past few years, I have been fascinated with the genus Ginkgo. My garden property could certainly not contain a standard Ginkgo which could reach 50 feet or more. Several years ago, I bought Ginkgo biloba ‘Marieken’ as I had been told that it was a dwarf form. It is a beautiful plant with soft green leaves that have ruffled edges and turn brilliant golden yellow in the fall. After about five years, it has a width span of about 6 feet and that is not what I would call ‘dwarf’.

Ginkgos Large and Small

In Portland, Oregon, Ginkgo biloba trees line the streets in an area called Park Blocks. These magnificent trees were planted years ago and today reach a height of perhaps 100 feet.  The Ginkgo is an excellent choice for a large street tree when taking into consideration the ultimate growth expected.  (Large tree lawns are a must.) They do not seem to be bothered by insects or diseases, are tolerant of air pollution and most soil conditions, and they provide shade in the summer and beautiful golden fall leaf color in the autumn.

Ginkgo History

An allee of ginkgos creates a spectacular fall display.

I have long been fascinated by these historic trees and marvel at their survival instincts.  Ginkgo fossils exist dating to over 270 million years old. At one time they were thought to have grown worldwide, but presently, remnant populations were found to only exist in China and Japan. Throughout Asia, these trees were revered as fixtures in temple gardens and Buddhist monasteries.

Ginkgo trees are monoecious, a technical term meaning that separate trees have either just male or just female flowers. It may take a tree 20 years or more before the flowers develop.  When purchasing a Ginkgo, select male plants, (grafted or grown from cuttings), because female trees produce messy, fleshy, ill-smelling fruit. In Asia, they use the fruits of the female trees for medicinal purposes, but they are not of value to most homeowners.

Ginkgo Size

Many ginkgo varieties have narrow, upright habits and no messy fruit.

There are several lovely large- to medium-sized ginkgo varieties. Most have been chosen for their unique, appealing growth habits in addition to robust growth and vigor. Those used as landscape trees are always seedless males. Two of the better available selections include the narrowly columnar ‘Princeton Sentry’, which only reaches 40 feet by 15 feet, and the excellent street tree ‘Magyar’, which reaches 50 feet x 25 feet and has a narrowly pyramidal shape with branches that curve upwards.

In my garden, I do not have space for a 100-foot or even a 40-foot tree. Most homeowners do not.  However, due to recent ginkgo introductions, there are some cultivars that I can and do grow.  Sometimes these are sold as being compact or “dwarf,” but it appears that the word dwarf often refers to a slow rate of growth rather than a small ultimate size. The plants might not be “dwarf” as we perceive the word to mean.  I have been growing these new dwarf cultivars in pots and have them throughout my garden.  With their slow rate of growth–even slower in a pot–they are easy to manage, and some selective pruning will keep them at the size that I want. (Ginkgos are classic trees for bonsai, so they are amenable to hard pruning.)

 

Dwarf Ginkgos

The leaves of the compact ‘Majestic Butterfly’ have beautiful variegation. (Image by Mike Darcy)

At the top of my dwarf ginkgo list would be the variety ‘Majestic Butterfly’.  It is the first dwarf that I purchased, and it continually attracts the most attention from visitors.  The annual rate of growth is considered 5-7 inches, so it has been very manageable.  The outstanding feature of this ginkgo is the striped green and yellow variegation on the leaves, though the color can be variable. Sometimes an all-green branch will pop up, but as it goes through the season, the variegation will appear.

Another favorite is ‘Marieken’.  It was discovered as a sport mutation in Holland in 1995 and is now in the retail trade.  In my garden, it has a semi-prostrate growth habit.  I have pruned it in such a way to encourage this habit, and it is now a spreading shrub of about 2 feet high and 6 feet wide.  The leaves have wavy ruffled edges and turn brilliant gold in the fall.

The dwarf ginkgo ‘Mariken’ is a bushy, spreading beauty.

The ginkgo ‘Jade Butterfly’ has proven to be quite popular with gardeners and should be readily available at nurseries.  It has dark green leaves that look similar to the wings of a butterfly.  It is another excellent ginkgo for a pot, and the unusual looking leaves draw much attention.  As it matures, it develops a shrubby, vase-shaped habit.

The Ginkgo’s Legacy

Ginkgos have long been used for bonsai and can withstand the harshest treatment.

With fossils dating the ginkgo back millions of years, the endurance and survival of the ginkgo was ultimately tested when they dropped the atomic bomb on Hiroshima in 1945.  Within days after the explosion, three Ginkgo trees sprouted new leaves.  These trees were the closest survivors to ground zero after the atomic blast.  Today they are part of the Hiroshima Peace Memorial Museum, and former Director Akihiro Takahashi summed it best when he declared that the ginkgos “expressed the endurance of hope, the need for peace and reconciliation.”