No-digging to avoid weeds

Press, 28 December 1989, Page 13

No-digging to avoid weeds

Organic Gardening

By

CLAIRE GRANT

Digging the garden over may not be as beneficial as some home gardeners believe. No-dig techniques are being encouraged for organic enthusiasts who want to avoid one of the problems facing any garden — weeds. Ministry of Agriculture and Fisheries Invermay scientist Dr Barbara Barratt says digging brings weed seeds to the surface, where they germinate and plants can quickly get out of control. “Avoiding cultivation means gardeners can get to the stage where weeds are not a problem.” Raising garden beds is one way of fighting weeds. Dr Barratt suggests gardeners try laying several layers of newspapers over the vegetable bed to suppress the weeds, and heap compost on top, making holes for the plants and to allow water in...

Black polythene can also be used to suppress weeds, anchoring it at the sides, with holes for plants and water. These techniques retains garden moisture and soil structure, while adding humus and nutrients, leaving valuable earthworms. Anything from well-rotted manure to sawdust or straw can be used as a mulch.

Vegetable seeds have to be grown in containers first, rather than sown directly into the garden, which may be more timeconsuming, but she says the no-dig technique has wide appeal, particularly with older people who find digging difficult. Gardens should be no wider than one and a half metres, with paths between, to avoid soil com-

paction through trampling. Most vegetable growers already know the benefits of compost, using simple grass clippings and dead leaves. Home-made compost that reaches temperatures of 60 to 70 degrees, kills most weed seeds. But Dr Barratt warns gardeners should know, exactly what they are putting on their gardens, and check its origins before it goes on.

“Hay, for instance, could have been sprayed, and may contain chemicals harmful to plants.”

Heat can also be used to kill weeds, and flameweeders are good for destroying them on paving or driveways. And another method used overseas is to lay strips of old woollen carpet upside down on paths, which successfully suppresses the weeds.

She believes organic gardeners need to have a more tolerant view of weeds.

“Weeds don’t do any harm if they’re not competing with vegetable plants for space and nutrients, and may be beneficial if their flowers attract pollinating and predatory insects. It’s changing attitudes from perfectly manicured gardens.” /

Companion planting, crop rotation, and selecting pest and disease-re-sistant plants are other methods used by successful organic gardeners. Many older varieties of plants are less susceptible to pest and disease problems. Dr Barratt recom-

mends gardeners choose resistant species.

It may also be worth while to do your own seed selection, by finding a plant that does not attrac; pests, and allowing it to seed.

One area that, can be looked at further is companion planting, or growing insect-repelling plants close to vegetables. Marigolds are a good example, and some people grow garlic in their rose gardens to repel aphids.

Dr Barbara Barratt suggests organic gardeners use a four-year crop rotation programme, with legumes in the cycle to build up nitrogen. This helps to avoid disease and pest build-up in the soil, which happens if the same crop is grown on the same spot every year. Growing manure crops such as lupins in vacant ground over autumn and winter for digging-in during spring, helps stop nutrients leaching through the soil. The “green crop” can be turned in, or harvested for compost or mulch in a no-dig garden, and it also helps to keep out weeds.