Plant Doctor Archive

Weeds in lawn

CAN you please help me with a weed problem that's appeared in my well manicured lawn? I've been told that because it's a grass, no lawn weedkiller will get rid of it. Is this true and if so what can I do?

THE sample you sent is buffalo grass (Stenotaphrum secundatum). It's a relatively common grass in coastal gardens in the North Island but is also found in northern parts of the South Island.

Buffalo grass is a tough spreading plant with wide bluish-green leaf blades. It grows best in full sun in light sandy soils - you're unlikely to find it in the shade or in moist areas. In the right conditions it can spread through your lawn.

None of the home garden lawn weedkillers will control it as they are designed to control broadleaf weeds. Any herbicide that kills buffalo grass will also kill your lawn grasses.

The only solutions I can recommend are that you dig out the buffalo grass carefully every time it crops up, or paint it with a solution of one of the many glyphosate-based herbicides available such as Roundup, Zero or Westminster or Butlers Glyphosate. Be careful not to get the weedkiller on the rest of your lawn. Once the buffalo grass has died you'll need to resow the bare patches with lawn seed.

Reproduced with permission from the former Weekend Gardener magazine. The views expressed here are not necessarily those of the RNZIH.