Our District

Mulch

Weed less, water less...

Mulch doesn’t just mean just wood-chip; it’s anything laid along the surface of the soil. Mulch keeps away weeds (providing it’s laid thickly enough), it helps retain moisture in the soil (meaning less watering over summer), and organic mulches (as opposed to pebbles) also break down to improve your soil, feeding soil life such as worms.

  • Spring and autumn are ideal as the soil is moist and warm.
  • Make sure the ground is wet – water first, if necessary.
  • Clear perennial weeds like kikuyu, dock or tradescantia.
  • Wet newspaper, cardboard or old carpet can be laid straight over smaller annual weeds, then covered with mulch.
  • Spread up to 10cm deep for a long lasting layer. A rake is handy for this.
  • Take care around plants – grasses and drought-lovers (eg lavender, proteas) can rot if mulch is too thick. Leave a space around tree trunks.

Once a garden has been thickly mulched – we’re talking a 10cm layer that fully blocks light reaching the soil surface – it should only need top-ups to cover any bare patches, for the next few years. Re-apply a fresh layer when the mulch has broken down and is no longer suppressing weeds.

Which mulch?

Cocoa husks make great-smelling mulch

 

 

 

Best value mulch: Grow your own - eg blue lupin – from a sprinkling of seed. Or use fallen leaves under trees or shrubs. Arborist chip is also cheap (even free from a friendly arborist!)

Best nutrients: Seaweed or compost. Use these for high-need plants like fruit trees and roses.

Best for veges: Straw is light and lets the rain through.

Best in a hot spot: Pebbles or rocks make long-lived mulch, in open areas away from falling leaves (otherwise they can become high-maintenance).

Best smelling: Cocoa husks are light but long-lasting, great around perennials.

Watch for:  Don’t smother tussocks and grasses with mulch. Their growing tip is at ground level, so keep that clear. Soft things like lavenders and succulents can also rot if over-mulched – use a drier mulch such as pebbles around these.

 

Tip: As I make my way round the garden, I've got three receptacles (which could be buckets, bags or barrows). One is for compostables – prunings, spent veges, weeds without seeds, leaves etc, all of which rapidly build up the compost heap. One is for bad weeds - oxalis and grass with seeds – which I don’t want in the compost. These go to the chickens or the drowning barrel. The last is a barrow of mulch - as each area is weeded, I try to mulch right away to stop weed seeds re-sprouting. This way each part that’s weeded, however small, will stay weed free over the summer.

 

The Council Green Gardener, Hannah Zwartz, offers sustainable and waterwise gardening advice to local residents, community groups and schools.

Community Visits and workshops are free. 

To contact the Greener Gardener, call the Council on 296 4700 or 0800 486 486 or see www.kapiticoast.govt.nz/greenservices

 

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