Throw Thuggish Plants in Detention

Container gardening essentials.

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Recently, as I was house-shopping in Austin, Texas, I visited one listed home that advertised “a bamboo grove,” which intrigued me because, despite its unsavory reputation, I’ve always wanted to grow bamboo. Arriving at the home, I was horrified to see a forest of bamboo that had taken over half of the large back yard and half of the neighbor’s back yard as well. Suddenly I understood why the house seemed underpriced. To view the results of such out-of-control botanical aggression was humbling.

And it reminded me why I’m so fond of container gardening. I bought a different house, and had a friend build me a large, simple wooden trough to sit alongside the patio. I purchased a bamboo plant, planted it in the trough, then stood over it, shaking my finger and saying sternly, “This is all the space you get. Now behave yourself.”

Alongside the trough, I set a lawn chair, a Japanese lantern and pots of ginger and jade, and I think of it as my little Oriental garden. I’m looking forward to the day the bamboo grows up and creates a mini-grove that will shade me and rustle in the wind as I lounge in my chair. I even imagine myself creating my own chopsticks, garden stakes and bamboo placemats. But when the bamboo fills the trough — and it will — I shall be ruthless.

Using containers is a good way to discipline unruly herbs, those invasive plants you don’t dare let loose in your yard. Garden writers call these “thugs,” and it fits. Once comfortably situated in the ground, they can be extremely difficult, even impossible, to get rid of.

When a thug entices you with its beauty, usefulness or sheer bravado, try it in a container instead of fighting or banishing it. Like any worthwhile detention, containers set clear boundaries. A bamboo plant wouldn’t consider a container its ideal location, but it’s OK that you and the plant have different ideas.

Protect the Neighborhood

Other plants in the herbal world require caution on the part of the gardener introducing them into a tidy garden, lest they conquer the gardener’s space and head off for the rest of the neighborhood. These are prime candidates for a life sentence in detention.

Some of these thugs owe their aggression to rampant growth habits and overwhelming ultimate size; pot culture slows down growth and can keep their size manageable. Other plants, such as mint, spread beyond their allotted space by sending out runners or underground rhizomes; containers also curtail these wandering ways. (But with bamboo, those tough rhizomes actually can break through clay or ceramics, so this burly plant is best contained in plastic or wood.) Others become pests by the ways they propagate. Dandelion, for example, disperses its seed far and wide, so growing it in a pot for its nutritious greens is fine, but if you aren’t conscientious about preventing it from flowering and setting seed, those puffballs will spread dandelion all over creation anyway. Wily horseradish is difficult to eradicate from a garden because once you think you’ve dug it all out, it can sprout from the tiniest piece of root left in the soil.

Sometimes, rather than growing the plant in a pot, it’s enough just to plant it in a container with the bottom cut off. Rambunctious mints and the tenacious horseradish, for example, can be controlled this way, planted in a plastic 5-gallon container with the bottom cut away. A barrier like this should be at least 10 inches deep; otherwise some thugs will barely break a stride in climbing over or under them. I might also try this with an aggressor such as ‘Silver King’ artemisia.

Your Homework Comes First

In finding alternate ways to grow plants that are too aggressive to put in your garden, a little research is helpful, because there are often dwarf cultivars of the plant or varieties bred specifically for container culture. I went online and quickly found plenty of information on bamboo. I was interested to know that there are many species, both clumping and running varieties. I chose a variety of Bambusa multiplex, a clumper. Growing it in drier conditions than is optimal, I’m hoping it will stay smaller and be content here in its trough.

I’ve mail-ordered another herbal thug — horsetail — as a companion for the bamboo, so the two can fight it out and have turf wars right there in their trough. Horsetail (Equisetum spp.), an invasive bog plant that grows at the edge of streams or ponds, is an intriguing herb because it is very old and primitive, has an interesting architecture and is so high in silica that it can be used to scrub pans or even sand wood. Like the bamboo, it won’t get quite as much water as it would like here in Texas, so it won’t thrive and get out of control.

When you put a tough, fast-growing plant in a container, watch to be sure it doesn’t get root-bound, which, like any overly oppressive form of detention, can kill it. When it fills the container to overflowing, take it out of the pot, cut back the root ball and repot. Consider this healthy maintenance and experimentation, not horticultural torture.

— Kathleen Halloran, former editor of The Herb Companion, recently moved to Austin, Texas, where she’s planting a garden again.