Earthworms boost Anchorage lawns and gardens, but at what cost?

Our back lawn looks like a football team ran across it in cleats, bringing up bits of rich, dark soil that slowly fade into the grass as it rains or they get stepped on. I couldn’t be happier.

Our backyard is covered in worm poop.

You undoubtedly have experienced earthworms of late and maybe even their castings. I know I am getting lots of questions about those lumps of soil all over lawns.

Earthworms come out of the ground when it rains, which it has been doing a lot of late, and move on the surface. They do so because they can cover more ground than they can in soil. This habit ensures species survival because they can lay eggs in new places. Note that their presence above ground is not because they can’t breathe when the soil gets too wet; total myth.

While there are about 1,800 species of earthworms in North America, only one is in Alaska naturally and that is in the Interior, where they were not wiped out by glaciation like the rest of our populations. I am talking earthworms here, Lumbricus, not glacial worms, aka ice worms (Mesenchytraeus solifugus) or snow worms (either Mesenchytraeus gelidus or hydrius).

What earthworms we see in our yards and gardens and on driveways and sidewalks are all imported. One paper on the subject of earthworms in Alaska noted 14 kinds of imported earthworms. These were let loose in our gardens and yards either purposely or because they came up in a potted plant or bag of soil and escaped in the spring or summer. Some come up the road system as eggs in cocoons, which are deposited and then hatch in the spring.

As gardeners, we deal with two species. Lumbricus terrestris, or the night crawler, is a relatively new one. These can burrow down 15 feet when it gets too cold, and unless we have a brutally cold winter with no snow cover, they escape the frost that would ordinarily kill them.

And, no doubt there are red wriggles in your yard, Eisenia fetida of worm bin fame. They can’t burrow deep enough when released so they freeze to death as our winter hits. However, they do lay eggs that make it through because they are protected in a cocoon.

Please note I recently had a report of a sighting along the Coastal Trail that is possibly a member of the Amynthas species, These are the Asian jumping worms, which move like snakes, are really fast for worms and sometimes look like they jump. They leave a yellow mucus slime when agitated. Use your browser to search “invasive Asian jumping earthworms.” If you suspect you see one, let me know ASAP.

Anyhow, the earthworms we see after rain and the ones that create that wonderful soil are invasive. We love them because they only want the invisible microbes on the leaf litter and duff they ingest, leaving us with “poop” that has 500% more nitrogen, 700% more phosphorus and 1,200% more calcium than the surrounding soil. Now you know why they are so valuable in the garden.

However, it is one thing to enjoy earthworms because they help us make wonderful lawns, yards and gardens. It It is another matter when you consider what happened to the area in Kenai where nightcrawlers have been released by fishermen and are now eating too much and too quickly. (By the way, apparently coho salmon love them, and they are a major food source.)

In short, earthworms are invasive. Normally, they move 30 feet or so a year, but gardeners importing wigglers and using soil with earthworm eggs have helped them far exceed that distance. In a few places within an hour of over half the state’s population, forest duff is being taken down faster than normal and this is not good. Once this mulch cover is gone, lots of things start to cascade in the wrong direction.

Gardeners do have an impact. Just look at our wonderful earthworms, which give us so much. Yet they are invasive and not always beneficial. As gardeners, we like to think that we are on the cutting edge of regenerative action when it comes to using the soil food web to do away with pesticides and herbicides, using batteries to reduce air and noise pollution, cutting back on plastics and doing lots of composting.

The point is even gardeners need to sit back sometimes and figure out our place in the scheme of things, particularly here in relatively unspoiled Alaska. Maybe composting our food waste is better than feeding worms in a bin.

Jeff’s Alaska Garden Calendar:

Alaska “Booootanical” Garden: What? So much stuff going on.

Alaska Pioneer Fruit Growers Association is hosting a free apple and fruit tasting event at 1-3 p.m. Saturday, Oct. 5, in the MidValley Greenhouse at 1418 S. Hyer Road in Wasilla.

Outdoor faucets and hoses: Don’t let those pipes freeze at the end of the season. Disconnect attachments from faucets. Drain them and drain hoses.

Clean up: Start putting stuff away.