Plant Doctor Archive

Problem with weeds

We moved here 18 months ago and have spent much of the time cleaning up and clearing the section of rubbish and garden waste. We have been attempting to get rid of huge quantities of oxalis and convolvulus and at the moment we appear to be winning. Unfortunately, while we have got most of our section clear, the neighbours on three sides have also got lots of convolvulus and are not keen gardeners like us. Do you know of any permanent way of stopping the convolvulus from coming back into our section? On one fence there is some corrugated iron which I think was supposed to stop it coming through, but the convolvulus has gone underneath and in between the spaces where the pieces have overlapped. We have used Round Up which has only been a temporary stopping solution. Any other ideas?

This is a hard one — I have the same problem at home with invasive plants coming into my garden from bush behind us. I am going to invest in a slasher! I have found the best way to get rid of oxalis is to dig it out and just keep digging.

Round Up is not very effective on convolvulus. It will tickle it, but has no lasting effect. However, Round Up does have the benefit of being non-residual.

The best spray for convolvulus is Woody Weedkiller. It needs to be applied when the plant is actively growing. Spring and autumn are a good time. Mid-summer is not a good time. The best way to treat it at this time of year is to clear the convolvulus by hand, and when new growth comes through, spray it.

Results are slow. You may not see any effect for up to four weeks after application. Repeat this process on any new growth. Take care not to let the spray drift onto other desirable plants.

The disadvantage of Woody Weedkiller is that it is residual and the ground cannot be planted for six months in the area that has been treated.

I would say the corrugated iron has been put in to try and stop the weeds coming through. Unfortunately, the depth you would need to go makes this an unpractical solution. It always seems to find a way through!

Other than talking to the neighbours and asking them if they can keep it under control, you will just need to keep plugging away at it.

Advice by Dr Dan Blanchon from Unitec's Diploma in Sustainable Horticulture and Bachelor of Resource Management.

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