Eucalyptus: Gumming up the Garden

October 2022

Eucalypts are notorious for giving off an
inhospitable, unsympathetic air.

—Murray Bail¹

This is a cautionary tale on the consequences of succumbing to the siren song of the genus Eucalyptus, an alluring but unwieldy throng of more than 700 species collectively called gum trees in their native Australia. I didn’t come across Murray Bail’s eponymous novel until it was too late, but even if I had read the narrator’s warning quoted here, could I have resisted?

The gum tree has a pale ragged beauty. A single specimen can dominate an entire Australian hill. It’s an egotistical tree. Standing apart it draws attention to itself and soaks up moisture and all signs of life, such as harmless weeds and grass, for a radius beyond its roots, at the same time giving precious little in the way of shade. (p. 15)

All this is true, and I found out the hard way. Like many a Pacific Northwest plant addict, I caught eucalypt fever as the new millennium dawned. By 2002 I had purchased and planted specimens of 14 species all around my 1/3-acre suburban garden. Although each one had been touted by local specialty growers as suitable for our cool, wet climate, (grown from seed supposedly sourced in high altitude, cold winter zones of southeast Australia and Tasmania), most proved themselves unsuitable in my garden. Within a few years the tally had withered by two-thirds as several were either slain by sudden, brutal cold snaps (as in November 2010) or deliberately killed by Yours Truly once I awoke to the reality of their obstreperous nature.

By 2012 a quarrelsome quartet of titans remained: E. neglecta, or “omeo gum,” which devoured ever greater chunks of our front garden; E. perriniana, or “spinning gum,” which insisted on growing at a precarious and terrifying 45-degree angle; E. archeri, or “alpine cider gum,” whose handsome and husky limbs grew like Medusa-head pythons that threatened the neighbors’ house; and E. glaucescens, the regal but rambunctious, ramrod-straight “tingiringi gum”² that ruled the roost at the eastern border of our garden near the edge of a wooded slope. Something had to yield. In April 2019 my long-suffering husband convinced me to call in the big guns, a crew of arborists who removed the first pair noted above along with reining in and cleaning up rogue portions of the latter two.

At this point we should consider qualities that render eucalypts appealing as well as abhorrent: On the plus side, they grow astonishingly fast (up to 10 feet a year in some types), their elegant, evergreen, pendulous leaves creating a shimmering curtainwall in even a slight breeze. Over the course of its life, a single tree’s bark can begin a powdery snow white that gradually morphs into a smooth suffusion of green, russet and tan patches, and later exfoliates stringy bark in huge strands that run to 12 feet or longer. Eucalypts exude essential, exotic and cleansing aromas that transport admirers, if not to Australia, at least to toasty, sun-drenched California.

Now for the unavoidable underbelly (Buyer beware!): Even young trees generate irritating amounts of litter virtually year-round through fallen leaves, wind-blown branchlets, exfoliating bark, and gum nuts (rock-hard, pebble-sized fruit). Much worse, these pesky particles as well as the tree itself are packed with flammable oils. As Bail notes, eucalypts are not good neighbors: They are water hogs whose robust roots siphon nutrients and suppress growth of nearby plants. In our generally soft, moist climate, their rapid growth prompts several frequently cultivated species to develop unstable root systems resulting in trees that grow at increasingly worrisome angles. Their roots can destroy sprinkler lines and sewer pipes.

Given this harsh reality, a throbbing question begs an answer: Is there an appropriate place for eucalypts in our maritime PNW gardens? I’ll proffer a tentative “maybe” —perhaps in a scenario involving an erect-growing, proven hardy species such as E. gunnii, E. glaucescens, or E. dalrympleana if planted at the edge of a large garden, far from inhabited structures.

Are you wondering about the fate of the two gigantic gums that remained in my garden after the 2019 purge mentioned above? Husband insisted we needed to remove both. He almost certainly had the better argument, but graciously agreed to a compromise. In April 2022 we engaged the same seasoned arborists to excise the ravenous E. archeri that not only loomed ever closer to the neighbors’ house but also engulfed a mature and much more appropriate Laurus nobilis (bay laurel) that is now breathing a massive sigh of relief. Our garden now sports a sole survivor: the drop-dead gorgeous but somewhat chastened 80-foot E. glaucescens, even though it has twice mangled nearby sprinkler pipes and continues to impoverish now anemic garden beds 50 feet or more from its base.

As a counterpoint to my caveats, I must promote a pair of local voices more experienced and erudite than mine on this fraught topic. The illustrious Ian Barclay (of The Desert Northwest fame) built a website several years ago for eucalyptus fans in our part of the world. It’s still available here. Also essential is the upbeat, 170-page monograph, “Cultivated Eucalypts of Seattle and the Greater Pacific Northwest,” by Robert Wrench, who was awarded a scholarship by NHS in 2019 to aid in completion of this comprehensive document. You can consult it here.

Let’s wind up this disquieting Halloween fable and meet again in mid-November.

Horticulturally yours,

Daniel

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1. From page 159 of the novel Eucalyptus, by acclaimed Australian writer Murray Bail. (New York: Farrar, Strauss & Giroux, 1998). Seattle-based author and literary critic Michael Upchurch reviewed the novel in the New York Times. You can read his assessment here.
2. Bail sprinkles his novel with colorful Australian common names for various eucalypts, such as pumpkin gum (E. pachycalyx), Kakadu woollybutt (E. gigantangion), gympie messmate (E. cloeziana), bastard tallowwood (E. planchoniana), and tumbledown gum (E. dealbata).