Q. Mike: Should I add earthworms to my raised beds?
- ---Chris in Summit, NJ
1): To help keep my soil aerated and pliable and fight the dreaded "ClayAchin'" of Delaware County, PA. &
2): To have a supply I can dig up and use to go fishing whenever I want. I have an empty 4' by 4' raised bed all ready for my worm condo. I just need advice on how to furnish it. Thanks,
- ---Pete in Glenolden, PA
The answer to Chris' question about adding earthworms is both simple and complex. Earthworms (like the abundant nightcrawler) are wonderful in garden situations. Give them some leaf litter to live underneath and they will constantly digest your garden soil, aerating it to relieve soil compaction and adding lots of trace minerals and other plant nutrients in the form of their famous 'castings', a euphuism that certainly sounds much classier than the 'worm poop' it is. Appreciation of these worms is one of the big reasons I use shredded leaves as the mulch of choice in my raised beds; I know that almost every time I move some of the mulch to one side, I'll see earthworms scurrying away to hide.
But allowing such worms outside a wriggly-good garden gets tricky. There is a strong consensus in the scientific community that many of the nation's earthworms are not native to the Americas, but came to our shores from Europe and Asia in the soil accompanying transported plants; and The Worm Book notes, in huge numbers when the ships of early settlers used soil for ballast and let it loose in The New World. These practices apparently re-introduced earthworms to areas where they had thrived in prehistoric times, but had been wiped out during The Little Ice Age. A lot of controversial plants in our landscapes have very similar histories. Do such origins make these organisms alien invaders? Or resettled natives?
No matter which way your brain tries to unpuzzle that puzzler, these earthworms seem to be changing the face of the American forest floor with their nutrient recycling. Although a richer soil would seem to always be a good thing, it favors the growth of some plants over others; and the fear is that the worms are putting added pressure on some native species.
So, as my good friend Frankenstein's Monster would simplify this complex question: "Worms in garden, good! Worms in forest, bad! Bad!"
I note this seemingly academic point because of Pete's desire to drown worms in pursuit of an aquatic meal or twelve. Fishermen—eh, fisher-persons—have gotten much of the blame for introducing these 'foreign' worms to forested areas, specifically by dumping their extra bait after a hard day of napping next to an anchored fishing line. So make it like trash in a national park: If you take it in, you haul it out. Or as our distinguished ex-president might say, "Leave no worm behind." (Which, of course begs the follow-up question: "Is our worms learning?")
In any event, the earthworm of choice for home gardens would be the nightcrawler (Lumbricus terrestris), a species that has become abundant (or is that re-abundant?) in North America. Unlike the redworms used for indoor worm bins, these worms like to go down deep—up to six feet under. The Worm Book notes that they prefer undisturbed soil for their permanent burrows, so if lots of worms you want, do no tilling. The less you do to disturb your soil, the more worms you'll have.
As their name implies, nightcrawlers come to the surface in the evening, so that's the best time to harvest a few for the next morning's fishing trip. The book adds that they're most active in the Spring and Fall; in winter and summer, they stay way down low during times of temperature extremes. A chilly (to me anyway) 50 degrees F. (10 C.) is their preferred number. I would think that a thin layer of vegetable waste from the kitchen on top of your soil covered with well-shredded leaves would provide the food they like to find near the surface and the cool soil temps they prefer.
If your garden area seems to currently be worm free, you might try some local wrangling to collect starter worms. A small-scale business in some areas, worm wranglers strap miner's lights to their forehead and go out collecting on rainy nights. And, you know, if these worms ARE causing problems in forests, it might be a mitzvah to collect them from the woods and take them to gardens.
Just remember: Nightcrawlers need to go down way deep and are not appropriate for indoor worm composting bins. And the redworms sold for use in indoor bins are not fit for gardens. You need the right worm for the right job. For lots more information on this topic, get a copy of The Worm Book. And read it until the pages are 'worm-eared'.