Rockery Plants - Part 1

As I said in my post on retaining walls and rockeries, Seattle is a city built on hills. Those hills are terraced with miles and miles of rockeries, which are planted, both accidentally and on purpose, with thousands and thousands of plants. Many of these plants bloom in spring, lining our streets with mini-explosions of color.

If you have ever wondered what any of these plants are, I'm here to help. In the next two posts, I'm going to take you on a little virtual tour of Seattle rockeries to help you identify some of the many plants you see blooming there this time of year.

This is a classic rockery plant combination: yellow Alyssum 'Basket of Gold,' paired with purple Aubrietia deltoidea. Aubrietia comes in both dark and lighter shades of purple; less common is a variety with deep rose colored flowers.

Candytuft (Iberis sempervirens) is a tough perennial with a long bloom time. It's one of the true bright whites (along with shotweed flowers) that you see early in the season. If you have this plant in your rockery, be sure to shear it after blooming to keep it from getting leggy. 

The red and green succulent plant spilling out onto the stairs is one of the many varieties of Sedum available in our area. Sedums are particularly well suited to life in a rockery because they require very little in terms of water, nutrients and care. 

The pink flowers on the left are heather (Erica sp.), the medium blue flowers in the middle are Lithodora, and the light blue flowers at right are periwinkle (Vinca sp). As with candytuft, all three of these should be sheared or cut back after blooming to keep them compact. In the lower left corner, new fronds, called fiddleheads, are emerging from a fern. To keep ferns looking tidy, cut away old, dried out fronds in late winter/early spring.

Wait! There's more:

Rockery Plants - Part 2

Picking Out the Pines

Do you have trouble telling one conifer from another? Do pines, cedars, firs and spruces all look the same to you? Well, after you read this post, you'll be able to tell the pines, at least, from all the others.

Here's how: pay attention to evergreen trees in your neighborhood this week. You'll notice that some of them have new shoots emerging from the tips of their branches that look like fingers pointing toward the sky.

These shoots look as if the tree is making the kind of rude gestures that humans do when they've been cut off in traffic. But don't take this personally, because these "fingers" are simply the beginnings of this year's growth for the pine tree. No other conifer produces shoots that look like these, so when you see them, you know the tree is a pine.

Over the next few weeks, these shoots, called "candles," will grow longer and shortly after that, new needles will appear along them. Depending on the type of pine, this will add anywhere from one to eighteen inches to the size of the tree.

You'll notice that some pines have white candles. (My guess is that these white shoots are what inspired people to start calling them candles.)

And that some have yellow candles. But they all work the same way.

You can shape a pine tree over the years by pinching the candles to stop or slow the growth of a branch. If you don't want a branch to add any new growth for the year, cut the candle completely off. If you want it to add some growth, but not too much, cut off just a portion of the candle. This technique is used in formal Asian gardens to train pines into a specific shapes.

As a bit of pine trivia, you might be interested in the fact that pine trunks offer a sort of record of the amount of rainfall from year to year. If you look closely at the tree on the left, you can see that there's bare trunk for several inches, then a whorl of branches, then more bare trunk, another whorl of branches, and so on. The distance from one whorl to the next is one year's growth. In rainy years, the trees grow more and the distance between whorls is longer; in drier years, it is shorter.





There are many pine varieties that grow well in the Seattle area. If you want to know more about them, the Sunset Western Garden Book has a lengthy section on types, growth rates, habits and more.