While many plants are hard-pressed to grow in our desert environment, others want to take over. Here's Dr. Angela O'Callaghan:

Horticulture is full of surprises. In fact, I often say that those of us who study plants and their effects on people need to avoid ever using the words “always” or “never”. Just when we’re sure we have everything under control, along comes a something totally unexpected. I have an example I’d like to share. 

We live in the driest part of North America, and of course, we need to be frugal with water. While I’m a devout believer in water-smart horticulture, my own garden has some idiosyncrasies. Most of the garden has desert landscaping – with lovely Mojave natives and plants from other deserts as well. They thrive with little water in our bright hot sun. Many of them haven’t been all that happy with our recent winter, but I’m certain they’ll come back to life with warmer weather.

So it’s mostly desert, but I had to create some exceptions, the most important being my little fruit and vegetable area. Most vegetables are from areas that receive considerably more rainfall than we get in Southern Nevada, so any vegetable garden needs to get a fair amount of water.

In that general part of the yard, I’ve been watching what I call the “celebrity death match” among three plants for the past few years. Each of them tends to be pretty aggressive, even invasive, and I’ve tried to keep them in check. But I’ve been only partly successful.

You might have already guessed the identities of at least one or two – Bermuda grass is one of them. I used to think Bermuda was the most awful grass on the planet earth, but since it’s the only thing that’ll grow in some rangelands, it can be important fodder for livestock or wildlife. Nothing is all bad, apparently.

Another aggressive and invasive member of my trio is mint. The previous owners planted it next to the house. Is there anyone who hasn’t heard that mint – peppermint, spearmint, the list is enormous – should be grown in pots, otherwise it’ll take over a whole landscape? That’s generally true, but it’s a good idea to expect the unexpected.

When I was outside this morning, looking over the winter vegetables, I glanced at the celebrity death match area.

The third member of the threesome was one I never expected to compete well against the other two. It’s Vinca minor, also known as creeping myrtle – no doubt you’ve seen it, smooth oval leaves and purple flowers. A master gardener gave me some cuttings about a dozen years ago and I planted them in a protected spot, hoping they’d survive.

They did. Each year, creeping myrtle’s expanded her territory. When I’ve looked at the three competitors, I’ve noticed that there were interesting dynamics, which is why I called it celebrity death match: most times the mint was muscling out the grass, but sometimes the Bermuda shot stolons up through the mint. The vinca just let its runners grow on the top of the mint and the grass, as if it were merely rising above the competition.

This morning, I saw just how effective that strategy’s been. I was trying to find some mint for tea. Yes, I had to paw my way through the creeping myrtle to reach a few scraggly looking shoots of spearmint. And yes, I could pull out the occasional long streamer of Bermuda, but the happiest plants in my garden, elbowing out the other competitors, was the Vinca minor.

I don’t exactly know how to feel about this. I’m not wild about any plant that can take over, but anything that overwhelms Bermuda grass is welcome. On the other hand, how robust must a plant be if it can outcompete mint!

I’m guessing that when the temperatures rise, the vinca will probably slow down and the spearmint’ll come back to prominence, but who would’ve expected this?

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