Cultivating dwarf conifers

The garden is put to bed. The pond liner is installed (hallelujah), the pea gravel is lying on top of the liner and the hole is filling with water (another chorus of hallelujahs.) The apples, pears and medlar (a small European persimmon) have been harvested and all the leaves are gone.

As I walk along grassy paths, the bony structure of the garden is apparent. All the imperfections are also visible: a “hole” in a border, elderberries crowding each other, autumn clematis overgrown, the bittersweet rampant but dwarf evergreens that grow slowly and gracefully and never push or shove other plants.

A dwarf may take 20 to 25 years to grow five to six feet. “Dwarf” is a relative term; for instance the popular mugo pine can soar to 50 feet in its original Swiss habitat. There is a tiny hemlock (tsuga canadensis, “Abbot’s Pygmy”) and a diminutive false cypress (chamaecyparis pissifrea, “Nana”) that reach only one tenth of the species size.

Conifers by definition are trees or shrubs that bear woody cones containing naked seeds. Junipers are included, and most conifers are evergreen; they retain their needle-like foliage all year round. However, some conifers, such as larch and bald-cypress, are deciduous, meaning they drop their needles like foliage as winter approaches and produce new foliage in the spring.

With notable exceptions, conifers (especially pine) need a lot of sun, and if they don’t get it, they perish. I have this fantasy of harvesting my own pine nuts, and I keep attempting to grow stone pine, only to watch the small trees languish and die for lack of bright sun. Surveying their tiny corpses, I solemnly promise to plant them where they will get adequate light next year and so forsake a rose or yet another fruit tree.

Conifers come in shades of green, blue, purple, gray, yellow, orange and khaki. Some conifers change color depending on the season, like pinus syvestris, or “Moseri,” which turns golden yellow in winter, and chamaecyparis thyoides, or “Heatherbun,” which becomes purple. Dwarf conifers in general have fascinating shapes and textures, and best of all they may be mixed with heath, heather or perennials on a hillside or in a rock garden.

I prune my dwarfs for shape even though they’re naturally small, but dwarf conifers should not be confused with bonsai, which are kept pygmy size by pruning. Dwarfs are genetic mutations that do not reproduce themselves.

In order to grow dwarf conifers successfully, the soil must be amended with composted leaf humus or horse manure. Dwarf conifers will not survive in areas of poor drainage, so consider hillside planting if standing water occurs in your garden. Conifers also prefer an acid soil, which is ideal for this area.

If they are only marginally hardy in Zone 5, conifers may suffer winter burn and actually die if exposed to freezing winds, so I plant them where they can be naturally sheltered by a large rock, neighboring shrub or on the southeastern side of the house.

In general I am not a great fan of mulch, but in the case of conifers, mulch is an asset if not a must and mulches can vary from leaves to gravel, crushed brick and stone.

I’m a great one for moving plants usually to their detriment, but in the case of conifers, they actually benefit from a short trip across the garden. When transplanting them, it is unavoidable for a little root pruning to take place, but this enhances their growth as the bruised root produces many rootlets. Planting or transplanting is best done in the early spring as summer heat is a greater enemy than winter cold.

My favorite dwarfs are the pendulous or prostrate varieties like pinus sylvestris, or “Hillside Creeper,” which only grows eight inches high, and tsuga canadensis, or “Sargentii,” which is a true weeper.

If you have any questions, comments or suggestions please send them to asknanny@riverreporter.com.