Spiraea thunbergii

Here's another shot of one of the moongates in the Enid Haupt Moongate Garden at the Smithsonian yesterday.  Breaking up the mass use of Magnolia x soulangiana, we have a very lovely spring shrub that is stealthily eating visitors as they walk on the adjacent sidewalk.

Well, probably not, but you can probably guess from this pic that the plant is a "vigorous" grower.  It's Spiraea thunbergii or Thunberg Spiraea.  Most hobbyist gardeners know Spiraea but are probably more familiar with the summer blooming S. bumalda.  S. x vanhouttei is another popular species.  But I have a soft spot for this plant. 

(By the way -- see something familiar peeking behind this plant??) I love the long slender stems that are densely packed with miniature rose-like flowers (indeed, this plant is in the Rosaceae family). The plant's been in bloom for a week or two now and the leaves are just beginning to emerge.  Narrow and lanceolate, they are also a great chartreuse shade of green that's much lighter than most shrubs. 

Spiraeas in general are bulletproof; they sustain drought easily and don't have any major pests or diseases.  Really the biggest hazard of having one is that it does need to be maintained.  If left unpruned it will get very scraggly and the inside of the plant will die off from lack of sunlight.

 

Below is one of my favorite uses of the plant -- it's a hedge at the Conservatory Gardens in Central Park.  It prunes easily and is so floriferous, that no matter when you prune it, it will still have a heavy flower set.  You can see that it's been probably a month or so since it was last pruned and the soft, fuzzy texture is such a nice change from yew and holly hedges. The shot below was taken in mid-summer and as you can see, the spring-green hue of the leaves has not darkened.