Tough trees need love

This time of year, give those hard-working evergreen trees a well-deserved drink

Sun., Dec. 21, 2008

By Beth Botts Chicago Tribune

Tips for evergreens

Provide enough sun: The green means leaves or needles are full of chlorophyll and photosynthesizing all year. That takes at least some sunlight, even in winter when evergreens’ growth greatly slows. But too much sun can scorch some species.

Site right: Evergreens always are in danger of drying out. Some people wrap them in burlap against winter winds or spray them with a coating, but that can clog the air holes in the leaves. Save yourself the trouble by planting evergreens where they won’t be battered by wind or sprayed by road salt.

The south side of a building is a bad spot, says Karla Lynch, education manager at The Morton Arboretum in Lisle, Ill., because heat from the low winter sun is reflected right onto the plant. And allow enough space for the mature size of the plant.

Be gentle: Don’t overload evergreens with holiday lights whose heat can dry them out; try cooler LEDs and tuck light strings gently between branches.

After heavy snow, let it melt off bent-down shrubs rather than whacking it away; chances are the branches will return to their normal shape with time.

Yellow needles? Relax. It’s normal for older needles toward the center of an evergreen to turn yellow and drop off each year as new growth is added at the ends of the branches, says Andrew Bell, curator of woody plants at the Chicago Botanic Garden.

It doesn’t mean the plant is sick. But if a whole branch turns brown, you may have a problem.

Be aware: Since an evergreen’s yearly cycle is more subtle than, say, a sugar maple’s, we may not notice it growing. That’s how the cute little Norway spruce planted by the front steps turns into a 60-foot house-eating monster that cracks the foundation.

The growth rate is affected by climate and sunlight, says Alan Craig, Midwest sales representative for wholesale grower Iseli Nursery Inc. in Boring, Ore., and there are dwarf cultivars that grow so slowly they won’t be knee-high in your lifetime.

Prune with care: Different species need different pruning; on most species, new growth can’t sprout from the bare part of branches.

Only a few species tolerate the heavy, labor-intensive shearing needed for geometric hedges. But evergreens allowed to keep their natural shape need only occasional removal of dead or damaged wood. Get specific instructions for your species before pruning.

Try something new: Many homes still have the shrubs that were planted when they were built, often sheared into rigid, coffin-like hedges or balls.

“It dates the house,” says landscape designer Paula Popowski of Knupper’s Nursery & Landscape in Palatine, Ill.

Today, a more casual and varied landscape looks fresher. And in recent decades, growers have developed a much wider choice of evergreens. You will find interesting foliage that ranges from deep green and dusty blue to almost yellow.

Some kinds have eye-catching weeping or contorted forms. Some, such as Iseli’s little puffs of white pines, are tiny enough to be planted in pots or tucked into a perennial border. Just be sure you get plants that are hardy for your zone.

Plant in spring: That way, new evergreens have all year to develop a root system and stoke it up with water before winter.

Indoors, up go boughs of holly. A green garland twines the banister. Candles are scented with pine. And at the heart of many homes, cloaked in regalia that sparkles with memories, an evergreen tree likely will be at the center of celebration, hugs and delight.

Outdoors, dark green shapes sulk unnoticed along the foundation – just something that came with the house, no more glamorous than the gutters.

Plants that stay green through Northern winters have been revered for many centuries for their power to endure through the darkest, coldest days, according to Michael Stieber, who runs the Sterling Morton Library at The Morton Arboretum in Lisle, Ill.

The holly and ivy, wreaths and Christmas trees we so enjoy are traces of ancient religions.

So don’t the evergreens in our yards deserve a little respect? It’s not easy, you know, living through all the craziness winter can dish out, with 20 pounds of lights on your branches, splashed with salty slush and with hardly anything to drink since September.

Evergreens are survivors. They keep their leaves for several years to conserve scarce nutrients in tough environments such as mountainsides and far northern forests, according to William Burger, curator emeritus of botany at The Field Museum in Chicago.

They can afford to make those needle-like leaves stiffer and sturdier than the single-season leaves of maples or sycamores, with a heavy waxy coating to hold in moisture.

But there’s a downside to keeping your leaves all year: You need to keep them filled with water. And when the ground is frozen, water can’t flow.

So let’s give a cup of cheer to the evergreens that brighten our yards and neighborhoods all year, by watering them whenever the ground isn’t frozen.

Hopefully, as winter approached, you made sure all evergreens (including azalea, holly and boxwood) had a chance to pack lots of water into their roots, wood and leaves. But even during December through February, any time water will soak in, seize the chance to water.

Pour a few buckets around the base of the plant or let the hose dribble slowly for a good hour at each of several spots over the roots.

Evergreens planted within the last two years are especially vulnerable. Of course, melting snow helps, but remember that snow is more air than water.

Figure out what you have; different species have different needs. Plants with needles (conifers) are a different ballgame than broadleaf evergreens such as boxwoods and azaleas. If you’re not sure, take pictures and branches to a good garden center.

No evergreens? Plant some. Evergreens provide winter cover for wildlife and, as the ancients knew, a winter lift for spirits.