Native Nurseries and the Invasive Jumping Worm Question

There’s a growing awareness in Indiana about jumping worms. We’ve seen more local news articles and social media posts this year than in past years. We've had some questions about our sale, and what is being done at nurseries to keep from spreading jumping worms. We promised to look into it, and we’ve received encouraging news from the nurseries we use!

If you don't know what they are, this very thorough, recent post "All About Invasive Jumping Worms", will help. It even includes a list of native plants that can survive in infested areas.

Photo credit: Hamilton Conservation Authority, Blog 03/22/2022 

The growers we buy our plants from have been aware of jumping worms for some time. But, by virtue of how native plants (and most greenhouse plants in general) are propagated in nurseries, it is unlikely that worms will be spread from them. Several specific growing practices make this unlikely. First, the soil-less growing medium that is the standard among commercial growers comes to the grower in sealed bags, and is sterile. (Note that the soil-less medium can look like soil but made of one or more components like peat, coco coir, perlite, sand, bark chips, etc.)

Second, the plant trays are on wire bottom tables and benches, at least 6” off the ground (since air circulation is critical for mould management and drainage). Usually, the ground is either concrete, or layers of rock for drainage. Growers are subject to inspections by the respective states to monitor for all sorts of pests and diseases, invasive and native alike. For instance, growers in states where the invasive spongy moth is present must treat with a short term insecticide prior to shipping to curtail their spread.

For our fall sale plants that are grown on the ground, pots sit on crushed limestone gravel. This isn’t conducive for jumping worms to live. They need a LOT of organic material to consume to survive.

In transit, the trays and pots aren’t in contact with the ground. 

We believe it is safe to say that nurseries aren't a notable source of jumping worm spread.

Jumping worms were originally introduced as fishing bait, and are still often associated with areas around lakes, ponds, and rivers, or where people have dumped unused bait. Indiana has no regulations against non-native bait worms; the sole reference to worms as bait is "Fishing worms should be discarded in trash containers." Indiana code detailing the regulations for bait dealer licenses says nothing at all about bait worms. 

Once our plants arrive at Geist Nursery, we have most on tables and benches, but temporarily store some of them on the ground. We are going to check the soil around the nursery. However, no jumping worms have ever been found there, and Geist Nursery has been bringing in plants from numerous growers for decades. 

Jumping worms are another reason to be extremely vigilant when sharing plants between private gardens, but appears to be of little concern when it comes to commercial growers.

What can you do? Be very aware when sharing and moving plants and when purchasing topsoil and compost. Ask your supplier! They need to know you care about this latest threat to our soils.

Other than that, a ounce of prevention is worth a pound of cure.  If there is any suspicion of contamination, wash bare root plants, and transplants. When in doubt, seeds are a safe way to share between gardens. If you DO think you have jumping worms, you can test by watering the area with a solution of ground mustard. Jumping worms will unhappily thrash their way to the surface. 

Also see Prairie Moon’s FAQ (last topic under “Plant & Seed Questions” heading.)

Banner Photo Copyright John Abrams under Creative Commons Attribution.