See these charming purple flowers in your yard? Destroy them immediately.

I have been trying to start up the debate I am certain Alaskans need to have regarding the introduction of non-native plants. We are the last place in the United States, unfortunately, able to have this discussion and still take some action to prevent disaster to our wildlife and natural plants. It has proven to be a difficult subject for gardeners to embrace and we have only been able to nibble around its edges.

Two plants that are vexing readers this month, however, serve as perfect examples of how powerful invasive plants can be. They also show exactly why we need to be more concerned.

The first was introduced by well-intentioned agriculturalists because it was a good cattle feed. Now it is on the loose, a mini Kudzu. I am referring to bird vetch, or Vicia cracca. Look it up if you don't know what it looks like. If you have it, however, you have to join me in wondering how anyone could not know the plant would spread. It produces seed like crazy and it can make lots of new plants that can form from underground rhizomes, too.

See, this is why it is a perfect example. It is the way with invasive plants. No one knew or, as I am finding out is the case with many Alaska gardeners, no one cared that the plant might become a nuisance. Well, we all care now. If your yard has bird vetch, you already know you need to take some action or your yard will simply be all bird vetch!

You can, and most definitely should, pull above-ground bird vetch and mow it down before it sets seed. Once the plants produce seed, mowing is a bad idea for obvious reasons. If you see vetch flowers, pull the stalks. Never let it go to seed.

The Co-op suggests putting down some sort of cover to act as a barrier after you mow if you want to clear a large area. Herbicides are also suggested, but these suggestions note that no one herbicide will control bird vetch in all situations. I will add that we surely don't need to compound our invasive problems with synthetic and persistent herbicides, so skip them and keep to the organics.

The bottom line? Keep at those bird vetch flowers.

The second example of an invasive plant that should make it perfectly clear that we need to stop introducing non-natives to Alaska is our old enemy, Campanula glomerata, aka the purple bellflower. Look it up on the internet, but ignore the captions that label it "vigorous and charming." Anytime you see a plant described as "vigorous" you are warned.

How did it get here? Somewhere early on, one was planted by a well-intentioned, pioneering gardener and because it proved to be a reliable, large, complex-looking perennial, people started passing it around. Today, those gardeners who received one have garden beds that are obliterated by thick mats of plants that don't let much else thrive.

It should be against the law, and certainly is already against gardening ethics, to offer or sell Campanula glomerata to anyone. If you have them, and no one has just one, pick those flowers, dig them up, burn them and if necessary use a weed barrier to prevent light from getting to them.

Jeff’s Alaska garden calendar

Mushroom walk at the garden: Fungi around the Alaska Botanical Garden are plentiful. Come with questions and mushrooms from your backyard. There's a $10 fee. You can sign up for Aug. 16, Aug. 23, Aug. 30 or Sept. 6. alaskabg.org

Harvest Day: 11 a.m.-3 p.m. at Alaska Botanical Garden Sunday, Aug. 12. Sample produce, herbs and fruit from the garden. Fresh produce harvested that day and canned goods donated to The Food Bank and Downtown Soup Kitchen.

Brussels sprouts: Wait for the frost before harvesting.

Slugs: Lure them out of the garden with beer traps.