Beware of some passalong plants

Lise Jenkins and Kit Flynn

The Absentee Gardeners

Courtesy photos

Last week I extolled the virtues of the Southern tradition of passalong plants – and this week I have to issue a warning. As I stated last week, sometimes the only way of acquiring a plant that is no longer at the height of fashion (and, yes, plants go in and out of fashion just like hemlines go up and sometimes down) is through the passalong process. This is one way we can maintain plants of historic values, plants that are closer to the original species before ultra-hybridization occurred. Old plants are part of our history.

However, there is a caveat: Many passalong plants are extremely vigorous to the point that they are invasive – and invasive plants should have no place in our gardens.

As the authors of “Passalong Plants” explain, not all old plants make good passalong plants. A passalong plant has to be easy to propagate. For example, my Euscaphis japonica, the Korean Sweetheart Tree, produces many seeds but the seeds must undergo an arduous process in order to germinate. Consequently, this tree, albeit a seedy one, is not a good candidate as a passalong plant.

Years ago, when I was relatively new to gardening, a friend gave me some yellow flag irises. Irises are desirable, right? This geophyte travels speedily via rhizomes, producing rather insignificant yellow flowers along the way. It has little merit. Fortunately, I hadn’t planted it near shallow water and could easily pull it out. Plant it near water and you’ll never be able to get rid of it. Instead plant the other irises, bearded, Japanese roof, Louisiana et al.

Generally, plants that are easily divided make acceptable passalong plants. Plant daylilies, crinums, aspidistra, and hostas to your heart’s content. It’s the ones that easily escape that you must be wary of. You wouldn’t plant kudzu, now would you?

All this takes some investigation on your part. A simple Google search would have informed me that yellow flag irises were best kept out of my garden. The authors of “Passalong Plants,” recognizing that some plants are undesirable, have a chapter on “plants that get away.” These are plants you must, under no circumstance, plant. Inevitably they have (1) lovely flowers, (2) delicious fragrance, and are (3) easy to grow.

An example of this is the Trumpet Vine, Campsis radicans. The beautiful flowers entice hummingbirds – but plant it near the house and it will unseat its shingles. It will grow anywhere there is sun or shade except perhaps in Death Valley.

Daylilies are safe except for the species Hemerocallis fulva, the orange daylily you see growing along highways. The tuberous roots travel and the seeds spread. Our native Bee Balm, Monarda didyma, while easy to pull out, can be susceptible to powdery mildew. Most bee balms flop while filling out spaces in the garden. Hybridizers now have produced clumping bee balms that can be divided. Depending upon your garden, these might be the better choice.

When I first saw Clematis paniculata (aka C. ternifolia), Sweet Autumn Clematis, I was overcome with lust. This is a dangerous clematis because (1) it’s beautiful; (2) it’s fragrant; and (3) it grows easily. Once planted, it will ensure that its seeds go everywhere – and you will never get rid of it. Beware of this plant as it’s sold everywhere.

A native wildflower to refrain from planting (although it’s widely available) is Trandescantia virginiana, Spiderwort. As the authors state, “It’s a bad boy that can’t stay put.” An added disincentive is that it’s so deep rooted that it cannot be pulled out. If happiness is picking up a shovel, this is your plant.

The last plant I’ll mention is Cleome hasslerana, an annual that arrived from the West Indies. This could be a perfect annual if it didn’t have small painful spines along its stem, a rather unpleasant aroma, and seeds that remain vibrant in the soil throughout the winter.

This article needs to be treated as an addendum to the original article. Passalong plants can be delightful additions to the garden. However, it’s mandatory to do your homework first. Otherwise, you could end up with a yard covered in kudzu.

Absent from their gardens, Kit and Lise enjoy roaming our region exploring the intersection of horticulture and suburban living. More on Instagram @AbsenteeGardener or email: info@absentee-gardener.com.