Digging In: Managing “Volunteers”

By Jennifer Smith

Fair warning, these plants can be quite generous! Most gardeners are familiar with plants that need division every few years. Hostas, lilies and iris are sure to come to mind. Having plants that contribute new offsprings makes it easier and certainly more cost effective to create a lush garden. The downside is they do require a bit of work. Digging an overly large hosta from the garden, dividing and planting new divisions is not an easy task. And there does come a day when we simply don’t need more of the same plant. Thank goodness for plant swaps and local plant sales! 

Then there are plants that run. The perennial plant of the year, Mountain Mint, is such a plant. The desirability of this plant to pollinators is second to none. In modest- or low-nutrient soil it stays where it’s planted, for the most part. But, if you are adding this to a garden you’ve been working on for years; adding soil amendments and loosening our tight, clay-rich soil, it can become quite a bully…but it is not invasive.

Many times, descriptors like invasive, vigorous or bully are used interchangeably to describe plants that spread or reseed with abandon. I offer a word of caution though in using the word invasive when describing the robustness of native plants. Native plans aren’t and can’t be invasive. Overzealous? Sure, but not invasive.

It may sound like I’m nitpicking, but as we are working so diligently to inspire homeowners to use native plants, I don’t want to muddy the waters and perpetuate the notion that a native plant is invasive.  We can still, and should, paint a clear picture of a plant’s behavior without labeling it as invasive. 

In our garden, we edit half of our Mountain Mint for it’s happy to take advantage of our ridiculously rich, loose soil.  Penstemon digitalis is also on a cautionary list. It reseeds quite well. Erect stems sporting an abundance of white tubular flowers in the spring garden is a sight to behold. No one regrets the plant then. But penstemon volunteers can overwhelm gardeners.  Well amended soil that’s not suffocated with shredded mulch will enhance the plant’s reseeding capabilities.  The plus side is a bumper crop of new, free plants and soil that is easy to work with. The downside of well-amended soil is that some plants may become too generous, and weeds may find a welcoming home also. To remedy this situation, I advise limiting the number of plants that reseed or spread via runners to a minimum if your time or experience in the garden is limited. Fortunately, baby Penstemon are immediately recognizable, making for swift, early editing.  

Solidago, a late summer bloomer, does wonders to extend the blooming season of the garden. I love Solidago “Fireworks.”  We have a few bands of this beauty meandering around the garden, and when it’s in bloom, it’s quite delightful. It does spread, though. However, again, in our loose soil, I can break off shoots with very little effort to keep the plant in my intended boundaries. It’s an easy edit any new gardener can handle.  

Rattlesnake master is a different story. Another native plant that’s beloved by pollinators, it loves to reseed, and does best in tight quarters, above and below ground. Individual plants have been reported to be short lived, but as it offers up new plants each year, that is not an issue. I notice that its preferred volunteer setting is tucked up against metal and cement edging around the garden. It’s not the easiest plant to edit once established. Luckily, young plants are easily recognized in the early spring so they can be whisked offsite before the roots gain a tight hold in the garden. 

Broomsedge is a native grass that I will admit, is not to everyone’s liking. In fact, I’ve yet to have a garden guest say it’s their favorite native grass. This may be a good thing as it reseeds, with new plants popping up far afield from the parent plant, making it not the best addition to a traditional home garden. Your neighbors may not appreciate this grass, native or not, volunteering in their garden. However, if you have a larger garden or an area where neighbors are not a consideration, I recommend adding this native grass to your landscape. 

If you are gardening for pollinators in the shade, you can’t go wrong with Aquilegia (Columbine). I include this native beauty in this column for it reseeds with much enthusiasm. Some gardeners may not like how it can fill in nearly all the open space in the garden. But this is exactly why I like it.  I have not found it to displace an existing plant. Rather, it fills open areas in the garden, adding to the garden’s lushness while helping to shield the garden from weeds.   

The key is to limit the number of plants you need to edit in relation to your skill and available time to garden so you don’t become overwhelmed.

Jennifer Smith is an award-winning pollinator garden designer with Wimberg Landscaping.