How to Stop Plants from Spreading – Guide/Pictures

While flower gardens are beautiful, having one or more plants spread via Rhizome Roots (or runners) is extremely frustrating. We can stop plant rhizomes from spreading by creating a physical barrier between your flower and the surrounding vegetation. And I’ll show you how to stop rhizomes with ‘recycled’ materials in this guide with pictures.

What are Rhizome Roots?

Rhizome Roots are small fleshy roots that grow horizontally underground and send up new stems/plants. Certain species will use rhizome roots to expand their area and beat out competition. Also known as runners, rhizomes can expand swiftly at great distance and speed and crowd out other plants.

Rhizome Root and shoot from Blunt Mountain Mint

How Fast can Rhizomes Spread?

Depending on species, rhizomes can grow and spread quite rapidly. To provide context, I had a small clump of a perennial sunflower that was about 6″ diameter at the end of the first growing season. During the summer/fall/winter it was secretly sending out rhizomes in all directions. I had no idea this was occurring, as no new shoots were visible above ground.

But the following Spring, I was quite surprised to find a solid mat of shoots that was 2-3′ diameter (1 m).

I remembered thinking (at the time) that I better do something about this…..

I took no action on my new ‘carpet’ of sunflowers. I guess I just forgot, or thought that perhaps it wouldn’t accelerate it’s expansion. Well, I was wrong and at the start of the 3rd year, the area had expanded to roughly 8′ diameter (2.5 m). I had new sprouts coming up everywhere – in between other plants, all over the place!

So, after spending about 2 hours carefully separating and removing shoots from other plant root systems, I had cleared the area. But, I still wanted to keep this plant but not have it spread all over. So what did I do?

Process to stop plants spreading via Rhizomes

I’m going to show you with pictures how I created a physical barrier to stop my flowers from sending out Rhizome Roots. This method works, and is long term as plastic doesn’t degrade.

Materials required

Old plastic flower pot, bucket that is 10-12″ tall (30 cm) and at least 6″ diameter (15 cm)
Knife
Shovel

Guide to stop plant rhizome roots from spreading

Remove the bottom of the flower pot. Use your knife to carefully cut around the bottom of the flower pot. Removing the bottom of the flower pot will still allow moisture/nutrient transfer. Worms will also be able to travel above/below the pot.
Dig a hole that is large enough to accommodate the pot for both diameter and depth. Generally, rhizome roots are quite shallow (<4″ deep). So, a pot that extends down 10″ is more than sufficient for containing rhizome roots. Also, choose a larger diameter pot.
Place your pot in the hole, and back-fill dirt inside/around the pot.
Plant your flower/rhizome root in the pot, and water it in.
Monitor your site to make sure there are no rhizome roots left in the soil in the area, sending out new shoots.