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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’.

4-Layer Easy Rock Garden Design

Created on a slight incline, this beautiful western rock garden featuring aloes, cacti, and local stones and cobble.

Alpine succulents from the Atlas Mountains flooded into 17th-century England where the climate and soils were totally unsuitable for growing them.  This created a learning curve for English gardeners. Daily summer rains and great soil explains why their gardens are so fabulous, but succulents need high sun, fast draining soil, and occasional watering to thrive. To compensate, English gardeners learned how to build rockeries or rock gardens.

Created along a driveway slot, this layered alpine rock garden shows the adaptability of rockeries to small spaces.

They learned that succulents could survive English winters if the soil was as well drained as a mountain scree.  In the wild, alpine species thrive on mountainsides where elevated natural pockets between the rock keep them high and dry. So, the elevated English rockeries were raised with rock and pebble and created on south-facing inclines. Contemporary rock gardens in the American West use similar techniques, but the plants grown are more tender species from South Africa and Mexico.

American succulent rock gardens are easy to make, sustainable, and demand little water.  Their size can be as small as a rocky trough or cover an entire front yard, but all must be sloped or mounded for increased drainage.  They are easiest to create on a preexisting slope that receives full sun. South-facing slopes are best.

Creating Layered Rock Gardens

Rock gardens are created in four layers.  Allow plenty of time for a thoughtful arrangement of the rocks; placement really matters.  Hand place materials to resemble a natural feature where each stone looks at its best and compliments the plantings. Without careful design and placement, rock gardens can look like rock piles!

Layer 1 – Place Anchors:  Anchors are key boulders and large rocks that are higher than the final garden grade. They provide height, help support smaller stones, and reduce erosion.  Set them within the bed area in a naturalistic, irregular arrangement that’s pleasing to the eye.

Layer 2 – Cobble/Rubble:  Stones on this layer range from slightly larger than your fist to robin’s egg sized.  They can be rounded river rock, cobble, or coarse crushed stone with sharp edges that grab the soil on slopes.  Rounded rock or cobble tends to roll or slide without the structure of supporting anchor stones. Leave gaps between the anchor stones to support and raise the planting layer on top.  Leave deeper pockets for planting larger plants.

Layer 3 – Fill Soil: Pour Black Gold Cactus Mix into all the openings between the cobble/rubble layer. Pack the mix well to avoid washouts.

Layer 4 – Gravel Mulch:   Succulents of all kinds love gravel surface mulch.  It prevents the mix from washing out and reduces slope erosion.  Its addition will result in conditions ideal for both tender and hardy succulents as well as small arid grasses and perennials.

Keep Planting!

A rock garden isn’t static; it’s always changing.  Alpine Sedum will spread into crevices and along stones to create vivid mats of color.  Bright Sempervivum will send up their tall blossoms in late spring.  Gorgeous Echeveria hybrids will prove to be the perfect accent plants for hot summer weather.

Over time, rock garden soils will settle and gravel will erode, but that’s okay.  It’s a natural process.  When soil layers become too thin, add more Black Gold Cactus Mix.  To slow erosion as you add the mix, loosen the soil at the bottom, incorporate the mix, and cover with fresh gravel mulch. If you want to create new planting pockets, just remove some small- to medium-sized rocks, dig a new hole, and add fresh mix.

Locally mined stone is more affordable due to the short hauling distance.  Visit a local rock yard and take a good look at what’s available in your area before you start your rock garden. Visualize what you want, determine the garden’s area and plantings, order the rock, succulents, and bags of Black Gold Cactus Mix, and you’re on your way to a fabulous new succulent rock garden!

Gravel mulch holds soil and is the perfect cover for arid grasses and perennials. (by Jessie Keith)