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Beyond Rhododendrons – Broadleaf Evergreens in the Garden

Rhododendron 'Calsap' a broadleaf evergreen

Rhododendron ‘Calsap’ a broadleaf evergreen

Rhododendrons are probably the largest group of broadleaf evergreens that are familiar to most of us. They can play a big part in adding substance and interest in the garden during the winter. I do confess it took me a while to understand the cigar roll shape those broad leaves take when the temperatures are very low, but I accept that even plants must protect themselves from the elements as best they can.

Rhododendrons come in a whole range of sizes and colors from low growing varieties like the pink ‘Yaku Princess’ to brilliantly colored shrubs that will tower over us. After visiting Jerry Sternstein, whose rhododendron hillside in Hawley opened my eyes to this range, I have added rhodies to my garden. ‘Boule de Neige’ is an old white variety, ‘Calsap’ is white with a speckled purple flair at its heart, and the deep red ‘Rangoon’ is not as tall but it spreads wide in maturity.

Rhododendrons need an acid soil that is moist and rich in organic matter. Its feeding roots are close to the surface and so need to be protected from heat and drought. Those feeding roots also explain Sternstein’s rule about planting, “Keep it simple, just a dimple.” Rhodies do not need a big deep planting hole, but after planting in a dimple a layer of mulch is good practice. Mulch helps keep the roots cool and moist.

Rhododendrons are considered a plant that likes at least some shade, but Sternstein’s rhodies flourish in the sun. It seems that some rules can be broken. The height of Sternstein’s garden is usually Memorial Day – hundreds of rhododendrons in full bloom.

Mountain laurels, Kalmia, have most of the same requirements as rhododendrons, rich acid soil, and dependable moisture. They do require some shade, especially protection from summer afternoon sun. The hybrids intended for home gardens usually range about three to four feet tall with about that much spread. The white and pink of the native mountain laurel is beautiful, but there are other shades and combinations in the hybrids that you will find in catalogs. ‘Carol’ has dark pink buds that open to pale pink petals,‘Firecracker’ has intense red buds that open to white and pink, ‘Peppermint’, as you might expect has candy stripes. ‘Minuet’ is slow-growing reaching three feet after ten years with bicolor blossoms of cinnamon and white. Again, be careful planting. Just a dimple.

Ilex Blue Princess holly

Ilex Blue Princess holly

I hadn’t ever thought of them that way, but hollies are counted among the broadleaf evergreens. I have planted Ilex x meserveae ‘Blue Prince’ and ‘Blue Princess’ and they have proven hardy even on my windy hill. All hollies are dioecious which means they require a male and female plant to produce fruit. Actually, you only need one male for several females. ‘Blue Princess’ is the more vigorous grower, but she needs her little prince to produce those red berries.

Ilex opaca’Compacta’ is a native holly that is similar in form to the shiny leaved hollies we expect at Christmas, but the foliage does not have that sheen. This variety will grow slowly to six or eight feet.

Ilex glabra ‘Shamrock’ is an inkberry cultivar. Inkberry is a broadleaf evergreen with fine small foliage and little black berries in late fall. It likes sun, but can tolerate some shade and doesn’t mind the wet. It can even be used as part of a rain garden planting. It grows slowly to a height of about four feet with an equal spread. It is a neat plant, and like other Ilex is not much bothered by deer or rabbits. Good to know.

Yucca filamentosa is another plant I don’t think of as an evergreen, but so it is. It looks like a southwestern sort of plant with its rosette of spiky golden leaves. In midsummer it sends up a five or six foot spike with panicles of fragrant, creamy white flowers. The spiky form is so unusual in a New England garden that it makes a great focal point. The fragrance is a surprise and delight.

Arctostaphylos uva-ursi ‘Massachusetts’, better known as bearberry, is a very low-growing evergreen; this variety has small leaves bordered in white. The words uva and ursi refer to the fact that berries are prized by bears. Birds relish the berries, too. A sunny spot with good drainage is ideal for this native groundcover. Don’t worry about fertilizing; bearberry doesn’t need it. Red berries appear in the fall, and are often used as Christmas decorations, as holly is.

To a great degree our gardens in winter can be a simple blanket of white – if we have cut back all the perennials, removed the shriveled annuals and weeded carefully. We are lucky if we have trees with interesting sculptural limbs, but without broadleaf evergreens or conifers the effect can be a little skimpy.

Next week I’ll discuss conifers, those cone-bearing evergreens like pines, spruce and junipers.

Between the Rows   January 17, 2015

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