Monthly Tips

March - Plant of the Month

Old Reliables

Looking at most yards in Seattle you'd assume this is really a town of about 15 plants. I can sit here in my living room and tell you 90% of the plants in 90% of the yards in Seattle. (This was not a scientific survey.)

First is the rockery containing heaths and heathers (the pink ones), candytuft (the white one), lithodora (the blue one), basket-of-gold (the yellow one) and bergenia (the one with big leaves that are always gnawed around the edges).

Elsewhere in this "typical" yard you find a large rhodie obscuring a window and getting blasted by the western sun; a juniper attempting to engulf the sidewalk and a weeping red laceleaf Japanese maple overhanging the drive and battering you when you get out of the car. In the shade are the speckled yellow leaves of Aucuba japonica. Sword ferns will be scattered here and there throughout the yard. Add a Pieris (dangling white bells, photo), some Douglas Fir trees, Viburnum davidii (a common gas station plant), a camellia and possibly a flowering cherry and you've got a typical Seattle yard. Okay, that's 16 plants but you get my point.

[Pieris blossoms]

In addition to their ubiquity, people don't like these Old Reliables because they are often poorly sited and have outgrown their spot. Because they've gotten too big, these plants get butchered to try to make them fit back in their appointed holes. This makes for ugly, and often unhealthy, plants.

So how do you make use of some of these tough old plants? First, take out any that are too big, too badly butchered or unhealthy. Just do it.

Then look at what your yard needs. Think of the plants as having a job. Do you need something 8'x8' to screen something? Do you need something evergreen that will fit under the windows? Do a little research and you'll find a number of old reliables that will work in that situation. You already know they are tough, and when properly sited, low maintenance. If you mix these in with a number of other woody plants, you will have the bones of an attractive low maintenance garden that is a little bit classic Seattle but with a lot more style.

Below I've listed the botanical names of all the plants discussed above in order. For some there are many cultivars to choose from with different sizes and colors.
Erica sp. (heath)
Calluna vulgaris (heather)
Iberis sempervirens (candytuft)
Lithodora diffusa
Aurinia saxitalis (basket-of-gold)
Bergenia cordifolia (also known as pigsqueak - try rubbing a leaf and see)
Rhododendron (100s to choose from, pick carefully, look for weevil resistance)
Juniperus tamariscifolia (juniper - I'd definitely go with other species in most situations)
Acer palmatum var. dissectum ssp. atropurpureum (weeping red laceleaf Japanese maple)
Aucuba japonica
Polystichum munitum (sword fern)
Pieris japonica
Pseudotsuga menziesii (Douglas fir - I wouldn't plant one of these myself, too big for most urban yards and there are prettier large conifers)
Viburnum davidii
Camellia sp.
Prunus sp. (flowering cherry - not an old reliable, just a common plant, they tend to be disease prone)

March - Tip of the Month

Insects and Pesticides

Things are eating your plants. Should you run out for a bottle of pest death? No, because all other considerations aside, pesticides often don't work. To understand why the don't work, you need to know a little more about insects and plants.

First, most problems with plants are not pest or disease problems. People often think there is a pest problem because a plant is sickly and they see a few insects around. The insects may not be responsible for the damage. Often insects attack plants that are weak; they may be causing some damage but they are actually a symptom of another problem. At the Washington State University Plant Diagnostic Lab, 1/2 of the sick plants that come in are not sick because of pests or diseases. Instead the problems are due to cultural or environmental problems like excessive or insufficient watering or cold damage.

Even if you do have an insect problem, spraying willy-nilly often doesn't kill what you want to kill (the plant-eaters or prey) and does kill things you want to keep alive (insect predators). If you don't know exactly what the problem pest is, you could be using the wrong pesticide.

In Eric Grissell's surprisingly enjoyable and beautiful book, Insects and Gardens, he says,
"If the fact that mites or ticks are not insects seems like a piffling frivolity that is inconsequential to the gardener, consider the fact that mites generally cannot be killed with insecticides but require miticides for control. The commercial manufacture of both insecticides and miticides proves that we need to know the name by which something is called even if for no other reason than to kill it."

[tools]

Rhodie root weevil and characteristic damage
Photo from American Rhododendron Society website.

Lastly, even if you use the right pesticide, you are unlikely to eradicate every individual of the pest you are trying to kill and often kill off most of the predators as well. Prey insects (the pests) that survive multiply quickly, quicker than the predators so often you end up with a worse infestation shortly after spraying.

So what do you do about your insect problems? Check for cultural problems (too wet, too much sun, etc.) and correct them. Then try hosing off the plant. If that doesn't fix things, find out for sure what the problem is (put it in a bag and take a sample to a nursery). Once you know your foe, find out the least toxic way of treating the problem and then decide whether or not you are willing to use what it takes to deal with it. In my yard if a plant tends to the sickly and insect infested it's gone. There are plenty of other great plants out there to try - maybe even an old reliable.