It's time to stop using non-native plants in Alaska gardens

I've mentioned in several previous columns that I have been having an internal debate with myself about the use of non-native plants in Alaska. It's time to bring it out into the open.

Simply put, does it make any sense for Alaska gardeners to introduce and use plants that come from places other than Alaska and to continue using already introduced plants from outside the state?

The deeper question really is if gardeners should plant anything that is not from their immediate area, but for the sake of simplifying this discussion, let's keep it on a statewide level.

At the outset, let me lay out some parameters. The concerns we should center on are two-fold.

The first is that a plant introduced into the yard for ornamental purposes might escape into the wilds and alter the ecology, possibly even causing economic damage. A perfect example of this would be the continued use of European bird cherry, Prunus padus L. as a landscape tree in Anchorage. You know it as the Mayday tree. Birds have distributed the trees' berry seeds and now they are the dominant flora along the city's riparian areas. Ultimately this could have an impact on salmon spawning in Southcentral Alaska.

The second is that nonlocal plants displace and often do not support the same wildlife populations as native plants. In short, they do nothing for the ecosystem but alter it. This is in part because native plants that would otherwise support local wildlife are displaced, and in part because exotic plants may not be attractive food fare for that local wildlife. Or, an exotic plant may attract one species that displaces some of the others that once prevailed. The difference between the ecosystem that a native tree or shrub can support versus an introduced plant can be staggering. Introduce the wrong non-natives and biological diversity and balance are screwed up. Take a look at a field invaded by hawkweed (Hieracium umbellatum). Nothing else grows there once it is established and only those animal species that like hawkweed inhabit the area.

Even though I could point readers to plenty of examples of the impacts (both ecological and economic) of planting non-native plants in Alaska, I can already hear the gnashing of teeth and practically read the comments that will flow from this column. I suspect some of these sentiments are rooted in the fact that Alaska is so big that if even if you added up all the land our yards occupy, the acreage would amount to a tiny speck against the state's vast wilderness. Planting non-natives here, you say — pushing the horticultural envelope on what we thought could be grown in Alaska (which is our prevailing mindset) — won't make a bit of difference in the grand scale of things, so give it up Lowenfels.

Am I crazy to think we should stop planting non-natives? I checked in with the one person I know has a handle on this problem, Professor and author Doug Tallamy, whose seminal book Bring Nature Home is a must-read for all Alaska gardeners (as we are going to have this discussion!). I posited the idea that due to Alaska's size we don't have to worry as much about non-native plants as gardeners in the Lower 48. His answer: "Alaska seems big now, but so did the Lower 48 at one time and now only 5 percent is anything close to its original state because of the attitude you described."

Professor Tallamy notes that invasive non-native plants act like tumors and once established, they can only be stopped with superhuman effort. He noted that 85 percent of Lower 48 woody invasives have come from the horticultural trade. Here in Alaska the percentage must be much higher.

In any case, Doug is correct: There didn't used to be a problem in the Lower 48. Now the entire country has been heavily impacted by invasive species. It's is a problem that costs billions of dollars. America isn't the same place any more.
We might not like it. The nurseries might not like it. The various garden clubs won't either. Still, we have to have this discussion if we want to prevent biological pollution that in the long run (and yes, this could be a long time from now), causes harm to this beautiful and biologically diverse state. We don't want to have problems like Australia, another place plagued by invasive species on the loose.

Here in Alaska, the problem is already happening to some extent, as documented by various government agencies, such as the Bureau of Land Management, the U.S. Department of Agriculture and even UAF's Cooperative Extension. If the conclusion is as unavoidable as I think, it's time for Alaska nurseries to get rid of anything that's non-native and instead concentrate on selling native Alaska plants — which we gardeners should be using in our yards instead of exotic, potentially invasive species. We will also need to discuss which non-native annuals that we currently use are also invasive — and stop using them.

We are all in this together. Time to take a hard look. Your thoughts?

Jeff’s Alaska Garden Calendar

Ice Candles and Luminaries workshop: Feb. 11, 1-3 p.m. Alaska Botanical Garden. Space is limited; register here: https://www.eventbrite.com/o/alaska-botanical-garden-832401305.