Rhonda Bracey: At Random

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

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!

Before pruning

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