Japanese maples rank among my favorite plants. They provide spectacular fall color, are easy to grow, thrive in our temperate Northwest climate, and don’t need much maintenance, except for some selective pruning each year. We have five Japanese maples on our property. Two are upright bloodgood maples whose purple-red leaves turn a brilliant crimson during the fall. The centerpiece, however, is a mature Crimson Queen laceleaf maple planted in front of the house. It has a graceful, weeping shape, with delicate layers that let in light from bottom to top. I’m particularly fond of this specimen, because it was one of the first I purchased and planted when I moved into the house seven years ago.

Because of their delicate appearance, Japanese maples may seem difficult to care for. In truth, they don’t need much — just well-drained moist soil and some protection from afternoon sun (though some varieties will tolerate full sun). These are hardy plants that do well in containers, if given water during the summer drought months. Most varieties grow well in the Northwest without much fertilizers. If you do fertilize, go easy on nitrogen fertilizers which stimulate growth and makes pruning more of a challenge.

To some, pruning Japanese maples can seem an art form. But really, it doesn’t take much expertise – only a good pair of pruning shears and some patience. Some experts say to avoid pruning maples in the winter when cuts on the trees are more likely cause it to ooze sap. We follow the advice of Cass Turnbull, with Seattle-based PlantAmnesty, widely considered the pruning expert in the Northwest. (Her pruning guide, by the way, is one of the books all gardeners should have on hand). Turnbull says any time is a good time for selective pruning of Japanese maples, but these trees are most easily pruned in the winter and summer. In an excellent article published in Fine Gardening, she writes:

With the leaves out of the way in winter, it is easy to see the branch structure and, in turn, make the right cuts. In summer, however, you can judge the right amount of thinning needed to see the tree’s bones. Summer pruning also stimulates less plant growth than winter pruning, so you can get away with a little more and the tree will stay thinned out longer.

Turnbull’s advice for pruning maples involves a lot of math and fractions, but they’re good rules to keep in mind: don’t take off more than 1/5 of the maple’s crown; don’t prune any branch that is more than half the diameter of the parent stem; don’t remove more than 1/4 of leaves on a given branch, since the leaves provide the plant with nutrients.

As with most pruning jobs, start by removing dead branches, branches that have criss-crossed, branches that are too vertical or horizontal, or those that touch the ground or crowd into other plants or hardscape. You want to be able to see between overlapping branch layers. Turnbull says if you plan to remove the lowest branches of your tree, take out only a few each time otherwise you’ll end up stressing out the plant. If you take one limb out, don’t take the one either directly above it or directly opposite in the same year. You often see Japanese maples pruned into an umbrella or mushroom shape, or not pruned at all so that they resemble a tumbleweed. There’s nothing delicate or pretty in this. Don’t try to hack off the top of the tree, otherwise, you’ll get lots of tiny branches that look like a mess.

It rains a lot in the Northwest, so it’s inevitable that many of us deal with moss in our lawns and on our roofs.

Mosses are opportunistic, thriving in just about any location where there is access to nutrients and moisture. Mosses spread in a number of ways, but they depend on moisture to reproduce, according to Oregon State University. Some mosses are extremely absorbent and are able to take up nutrients from water that flows over them (for example, under a shady tree where it’s wet and moist). Other mosses take up nutrients directly from soil (i.e. bare patch in your lawn) or substrate on which they are growing (i.e. cedar shake or composite roofs). So it’s no surprise that mosses take hold on our sidewalks, rooftops, driveways, trees, and in our gardens.

Moss in lawns
Many people view moss in lawns as a problem. With the exception of rooftops, mosses don’t necessarily cause damage. Moss doesn’t kill your grass. Moss in your lawn is usually symptom of a stressed lawn. Most likely, you’ve got poor drainage, excessive shade, poor fertility or compacted soil. Moss grows because these conditions aren’t idea for turf. Unless you address these underlying problems, moss is likely to return. Consider improving soil conditions, or planting something other than grass in that area. Some good substitutes for grass in areas where mosses thrive include blue-star creeper, beach strawberry (a Northwest native) and sweet woodruff.

beach strawberry

If you’re determined to get the moss out, there are both physical and chemical controls. Moss can be killed with a number of products containing ferrous sulfate, ferrous ammonium sulfate, including Moss-Out and lawn fertilizers that contain some type of moss control. According to the Washington State University Extension, none of these materials pose serious threats to the environment; iron and sulfur are essential nutrients for grasses and tend to improve their color. Using chemical controls such as Moss-Out can be quick, easy and relatively cheap. But they won’t actually fix the problem in the long run. Why? You can kill the moss, leaving bare dirt. Since the conditions weren’t great for grass in the first place, moss will continue to grow and invade that particular area of your lawn.

To fix the underlying problems that promote moss growth: improve soil conditions by aerating or amending the soil with compost; trim tree limbs or shrubs that shade out portions of your lawn; plant shade-tolerant grass seed or ground covers; improve grass growth by mowing at the right height and cutting off no more than one-third of the blade at a time. For areas where drainage is a problem, you may also consider installing a French drain or trench to prevent water from pooling up in certain areas of your property.

Moss on rooftops
Moss on rooftops can damage shingles, cause water leaks and other problems. Cedar shake and composition roofs are more vulnerable to moss problems than metal roofs (remember how moss takes up moisture and nutrients?) Again, there are chemicals you can use to get moss off of rooftops. The Washington Toxics Coalition has this handy fact sheet with suggestions on how to prevent moss on your roof:

• Keep tree limbs from touching your house or roof;
• Trim overhanging branches to reduce shade and falling leaves;
• Keep your roof clean;
• Sweep off pine needles, small branches, leaves, which are breeding grounds for moss;
• Use a garden blower or a broom; don’t pressure wash composition roofs because it’s the quickest way to reduce the life of your roof;
• Look out for early signs of moss growth, indication by green or black discoloration. Spot treat with moss-killing soap;
• Consider mounting zinc strips along your roof peaks or beneath shingles.

If you do use chemical controls, the Toxics Coalition recommends soap-based products over acid-based ones. It lists some of the least-toxic moss-killing products: Safer Moss & Algae Killer and Surface Cleaner II; Bayer Advanced 2-in-1 Moss & Algae Killer; Worry Free Moss & Algae Control; St. Gabriel Laboratories Moss Killer. The group recommends that you avoid products containing zinc sulfates or copper sulfates because these chemicals are not biodegradable. Also, the group says, be sure that rinse water does not run off the roof or street and directly into a body of water.

When I was growing up, one of the chores my dad assigned us four kids was to keep the front and back lawn evenly watered and emerald green. My dad never installed an automatic sprinkler system, let alone put a timer on it. Why would he need to? He had four perfectly capable children whom he could assign to hand-water the lawn. I remember countless mornings when my siblings and I would take turns going out to water the lawn before the hottest hours of the day descended. We would methodically move the spray nozzle from section to section, making sure to moisten but not over-saturate the grass.

Thank goodness for advances in technology. My dad was trying to be efficient with his water use — i.e., watering in the morning so as not to lose too much to evaporation; avoiding excessive run-off by not watering too much — but smart irrigation technology has made the whole process so much easier. Much like smart technology that has allowed us to set and control the thermostats in our homes, smart irrigation technology allows us to set how often and how much we water our lawns or landscape beds.

Traditional timers allow you to set a sprinkler system to turn on and off when you want. Smart irrigation technology senses weather changes and adjusts the irrigation accordingly. If it rains, it stops watering. (How many times have you seen sprinkler systems running when it’s raining out? This would certainly put an end to that.) If it’s hotter or the soil is drier than usual, the controller will increase watering. The controllers do all the work, and they are a much more efficient and sophisticated way to reduce outdoor water use. Studies show that weather-based irrigation technology help reduce outdoor water use anywhere from 15 to 30 percent, depending on the type of controller and where it was used. One study involving Denver, Colo. and two locations in California found that average individual homes save between 7 and 25 percent in water. If you’re interested in reading more, the U.S. Bureau of Interior did a literature review of studies involving smart controllers.

Many cities such as Seattle offer rebates for households that install smart irrigation controllers. In Seattle, the rebates range from $50 to $500, depending on what you install and whether it is on a new or existing sprinkler system. A smart controller on a new sprinkler system can net you rebates of between $225 and $375. You have to submit your rebate application within 90 days of installation. Click here to read about an irrigation project we completed in North Seattle using the latest in smart irrigation technology, which qualified the homeowner for a $480 rebate from Seattle Public Utilities.

Rotating spray-head sprinkler nozzles are also a new innovation in irrigation technology (shown above in top photo). They apply water more slowly and evenly than conventional sprinkler nozzles. The nozzles shoot multi-trajectory, rotating streams that apply water more uniformly. The water that shoots out of these rotating nozzles is less likely to mists and more resistant to wind. Applying water slowly allows soil to absorb it without running off into the sidewalks and streets.

Check out this city of Seattle brochure for more information about how to water wisely while keeping your landscape healthy and beautiful.

Contact Ecoyards if you’d like to have a smart irrigation system installed on your property.