Invasive species

Asked September 13, 2020, 11:39 PM EDT

Hi, I just looked over the Invasive Species list and became concerned, as I grow several of the plants listed in my community garden. They are as follows: - mint (in a container) - chamomile (in a container) - yarrow (in a container) - forget-me-nots (in the soil) - daffodils (in the soil) - crocus - was planning to put the bulbs in the soil Should I remove all of these immediately? Can some of them be grown “safely” in containers? Thank you so much in advance for your input.

Montgomery County Maryland

2 Responses

Invasive plant lists vary considerably depending on what authority is being consulted; different organizations will rank plants' invasive tendencies differently, and weather, soil type, and other factors can also influence how weedy a particular plant is at any given time in any given place. Usually, invasive behavior among plants is defined as that which displaces natives and disrupts ecosystems, plus causing economic harm, costing a lot to control or remove from crop fields or causing damage to the crop itself. Here are some examples of problems caused by invasive plants:
https://extension.umd.edu/hgic/topics/introduction-invasive-plants

https://extension.umd.edu/hgic/topics/invasive-plants-cause-ecosystem-level-changes

The particular plants you list can be weedy and aggressive but aren't usually denoted as invasive per se. They can persist in wild areas (like daffodils that still return from homesteads long-gone and in ruins from decades or a century ago) or self-sow or spread via stolons in the immediate vicinity (like mint), but don't take over swaths of wild land or invade disturbed areas. As an example, a site along a highway that was bulldozed for road expansion may see hundreds of Callery Pear tree saplings appear, Purple Loosestrife growing in the low wet spots, and Phragmites take over a water retention pond. However, the same site won't likely see any daffodils (those in highway drifts were planted), Forget-me-Nots, or Yarrow; they don't disperse as readily and the plants can't compete as vigorously with native colonizers and these other more truly-invasive species.

Confining aggressive plants to containers will help, yes, as often they are aggressive through vegetative means (runners, stolons, bulbs) rather than by seed. We would not be overly concerned with these species; instead, some of the most problematic species aren't even sold as garden plants (at least, not any more) and others are beginning to be regulated by the MD Dept. of Agriculture. Many of the worst offenders are listed here: https://extension.umd.edu/hgic/topics/invasive-plant-photos-and-information

Miri

This is amazing information - thank you!