Invading roots

31 05 2017

Guarding the entrance to our house are two massive strelitzias (Strelitzia nicolai). They have the most enormous flowers, and are just beautiful. But they have a dark secret — a root system that’s pretty invasive.

Magnificent white flowers of the Strelitzia nicolai

Magnificent white flowers of the Strelitzia nicolai

I’d suspected them of causing some driveway problems — cracking the asphalt, splitting the kerbing — but internet searches weren’t conclusive. One camp said these things had invasive roots and not to have them in your garden; the other camp said they were fine and no problem.

Over time I’ve noticed more cracks in the driveway near these plants and more recently, raised bumps and split kerbing (where there’d only been a hairline crack before). I also read a gardening article in our state’s main newspaper where someone had Strelitzia nicolai plants excavated (!) and was concerned about the roots and whether they’d sprout or if they needed to be dug out too. The gardener’s response was that no, they wouldn’t sprout, they didn’t need to be dug out, and she could plant something else in the hole.

I spoke to my garden guy and he suggested the cheapest solution for me as a first step was to prune the huge old branches, leaving the newer branches intact. He said that would likely stop the roots from invading any further, at least until the newer branches got as big as the old ones. The more expensive option was to get them cut out entirely and the roots ground out, ready for another plant species to take their place. I decided to go with the less drastic measure as a first step, and see if that solves the problem for the next few years. If I get no further cracking of paving or kerbing, I’ll take that as success, and make sure the older branches get pruned every few years.

During pruning - look at the height of that plant!

During pruning – look at the height of that plant!




Before pruning

Before pruning


After pruning – we can see the house over the road now, but have lost the magnificence of these big plants




4 responses

14 02 2021

Hi Rhonda, did the trimming help with the root issue you were seeing? Thanks

14 02 2021

Hi Jason

Yes, I believe so. The movement of the kerbing seems to be at a standstill, and I haven’t noticed further cracks in the driveway since my handyman filled them in with asphalt.


31 10 2022

Hi Rhonda! I have a beaut Nicolai growing right up against my house. It’s lovely to look out the window and seeing the gorgeous flowers, as this is the first time it’s ever flowered. I really do wonder however, if the roots are dangerous for my house foundations as it is literally up against the house, or will the roots just grow away from the foundations? Any suggestions?

31 10 2022

Hi Brian

I’m, certainly no expert so I think you’ll need to speak to a person who knows a lot about these plants and/or an arborist who may be able to guide you. Based on my experience, had these been close to the house, I would have had them removed.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: