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Invasive species can lurk everywhere from seed packets to aquarium tanks

  • Author: Jeff Lowenfels
    | Alaska gardening
  • Updated: March 18
  • Published March 18

Closeup of a bright yellow flower Sow Thistle or Sonchus arvensis, classified as a noxious weed. (Getty)

The bark beetle has not gone away. Trees are still turning red and losing needles. Alaska is under attack by all manner of invasive species, and the spruce bark beetle is just one. We see some of these invasives growing along our highways, spread by automobiles. Now, we are beginning to see thistles in our lawns and parks (not right now, of course, but you get my drift). There are even some invasive species we don’t see. It is a very bad idea to try and bring in seed potatoes, as these can spread microbes we do not want here.

I bring this up because I am getting an unusual number of email alerts urging me to tell readers that they need to stop growing moss balls. What am I missing? I looked them up and discovered they are beautiful little balls of algae that can live up to 200 years. These are aquarium plants, or at least grow in tap water, and not terrestrial ones.

I am pretty sure there are a limited number of readers impacted by what amounts to a recall of moss balls. They carry zebra mussels, a really, really, really seriously bad invasive bivalve we do not want in our waterways. I won’t waste more space here, but the alarm was serious enough that if just one reader acts (and does so according to the methods recommended by the U.S. Fish and Wildlife Service), our Alaska world will be a much better and safer place. If you have moss balls in your tank, google how to destroy them. Do it right now.

OK, segue: This is as good a time as any to once again caution readers about buying or starting invasive plants. While there is a legal definition and list, gardeners know what happens when the wrong plant gets loose in the yard. Be careful when buying seeds, particularly wildflower mixes. I advise you make your own and avoid the self seeding annuals many packets feature so they will come back every year. I have noticed several that contain questionable plants, not invasive in a legal sense‚ but surely weedy. Be careful. Avoid self-seeding annuals like a plague. And, only buy local potatoes. Your favorite nurseries carry them.

Next, I suppose some spouses would consider tomatoes invasive plants. I am pretty sure mine walks into our outdoor greenhouse thinking there are way, way too many tomatoes and not enough zinnias. We are almost at the April 1 date when you can start tomatoes without supplemental lights, and in fact should.

That being the case, now is when you should be buying tomato seeds if you have not already. I learned something this week about seeds. Species and strains carry distinct bacteria under those seed coats. When you grow an heirloom developed in New York, it will have those bacteria. Here, it will have those transferred to soil when planted, but they may get outcompeted by local Alaska microbes. That heirloom becomes yours.

In any case, all seeds carry beneficial bacteria. Do not use hydrogen peroxide to try and sterilize yours. Bacteria are needed for good gardens.

Moving on, in the fall, I recommend storing tuberous begonias right in their growing containers. This is not always possible. If yours are not in soil, it is time. Exposed to light, they should soon show tiny, little growths in the concave dimple in each. Either way, now is the time to plant in soil and get them growing. Gently push tubers, concave side up, into soil, covering up to the rim, but do not fill in the concave area.

Nurseries are open. Mask up and get shopping.

Jeff’s Alaska garden calendar

Alaska Botanical Garden: Ever consider volunteering? It’s fun, and the companionship is terrific. Plus, you learn stuff from Wil and the great staff. Check out opportunities, classes and more at

Seeds to start: Lobelia (needs 20 days to germinate; seeds need light so don’t cover), snapdragons (10 days to germinate and need light and cool temperatures), carnation (2 days to germinate), verbena (20 days to germinate), Pelargonium.

Herbs to start: Lavender, lovage, lemon balm

Corms: Glads, unless you want to plant them directly

Tubers: Dahlias, yacons, begonias