Saturday, April 16, 2011

Shrub of the Week: Spiraea thunbergii

It's been a truly sensational year for the Spiraea thunbergii. That's right, a kind of spirea. When I tell people it's a kind of spirea most people follow with, "oh, bridalwreath". As I often have to correct, this is not bridalwreath spirea (Spiraea prunifolia) but a different species known commonly as a Thunberg spirea, or as I prefer, Spiraea thunbergii. There are something like 70 spirea species out there which I myself had little to no idea. I've become fond of this Chinese native, having learned about it via the Conservatory Garden in Central Park where it's used as one of the many different hedges throughout the nearly 6-acre formal garden.
Left to their own devices (and not hedged) these shrubs would not be very different in size, but would certainly have a more rounded, upright habit with tons of the fine stems and branches arching outward. A member of the rose family, this sun lover has tons of tiny little buds all up and down their slender stems that explode this time of year, and what a year indeed.
I can't say I've ever seen these bloom so exquisitely in the few short years I've known them. The individual white flowers are smaller than your pinky nail, but with thousands and thousands of them you obviously can't go wrong. And the best parts have yet to come. This summer these guys will give way to a vibrant brighter green foliage that plays wonderfully off the slender stems of reddish brown, the leaves thin and lanceolate to further provide great fine texture to the landscape. I then love when they drop their leaves in fall and you are left with nothing but the killer cinnamon reddish wood, which literally seems to glow in the evening winter sky when placed with rich green conifers. I'm telling you, a shrub worth knowing. From my mentors I am told it is more of an old fashioned shrub and not so common in the trade but I admit I'm out of the loop on this one. It's been a while since I was a nursery plant slinger.
Spiraea thunbergii
- native to China
- hardy in Zones 4-9
- typically grows to 3-5' feet tall and easily as wide
- white spring bloomer
- member of the rose family, Rosaceae
- needs full sun and halfway decent soil

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