19 Mar 2018

Getting on top of your weeds

From Nights, 7:12 pm on 19 March 2018

A few weeks ago, Queensland ecologist Wendy Seabrook told Bryan Crump how to get weeds to work for you in the garden – rather than killing them at the first opportunity.

Bryan Crump's chickweed

Bryan Crump's chickweed Photo: RNZ / Bryan Crump

The interview garnered a fair bit of interest, but Wendy readily acknowledged there was one question she couldn't answer herself – what about the weeds we have here in New Zealand?

Remember even the concept of a weed is a social construct, says Manaaki Whenua - Landcare Research ecologist Colin Meurk.

"To some extent, our attitude to them has got something to do with our attitude to tidiness.”

Letting so-called 'weeds' do their thing is not a good idea, as they'll compete with other plants for nutrients, water and sunlight, he says.

“It’s a common misconception that tall herbaceous growth protects other plants, but in fact, they are competing and sucking water and nutrients away from our desired plants.”

Better to cut them down and lay them on the bare soil to protect it from erosion as they rot down, Colin says.

If you are planting weeds as a green mulch, legumes such as medick and clover are best.

“Leguminous plants have nodules on roots that grab nitrogen out of the atmosphere and turn it into nitrates that are available to other plants. So they are companion plants and are complementary to the desired herbaceous crops that you’re trying to grow.”

Recently, Bryan Crump has left his garden untended, letting the weeds grow to see if there are any benefits for the soil. Check out all eight of the ubiquitous ‘weeds’ in his garden:

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