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Should I Use Weedmat In My Garden?

One of the biggest problems I see in gardens are plants dying or at the very least failing to grow because they are surrounded by weed mat. I now routinely recommend to my clients to remove weed mat in their garden beds and once I explain why, most are happy to do so.

1 / Compacted Clay Soils

Most gardens on Auckland’s North shore have a clay soil type.  Clay soils are often berated for getting waterlogged, causing root infections for plants and being difficult to dig – all of which are true. However, clay soils are full of essential plant nutrients too. 
When weed mat is put on top of a clay soil and then pebbles or mulch placed on top of that, the soil becomes compacted and hardened.  This can lead to anaerobic and waterlogged conditions during wet conditions, which causes plant roots to rot and die.

2 / Barrier To Growth

When trees and shrubs are planted through weedmat, their growth  is obstructed by the matting around their base.  Not only is their spread restricted but also you are unable to directly fertilise the plant & its surrounding earth (with a granular fertiliser or sheep pellets) as these products can't access the bare ground, due to the weedmat being there.  

3 / Mulch, mulch, mulch

So if not weed mat, what else?  Adding a thick layer of mulch onto your garden beds does the following beneficial jobs for your garden.

  1. Mulch helps suppress weeds coming from below the surface by blocking out weeds access to light.  Note, weeds will grow due to seeds being transported by the wind and birds, but these weeds that land on the surface of the mulch can easily be pulled out.
  2. Mulch keeps moisture in the soil over the summer.  This helps reduce plant stress over a long hot summer.
  3. Mulch protects the soil from erosion by wind and also stops shallow rooted plants being burnt by the sun.
  4. Mulch breaks down over time and adds organic matter & nutrients into the soil.  For clay soils, that are low in organic matter, this helps create a better quality soil in which your plants can thrive and grow.

At Sculpt Gardens, we like to use a natural looking ground hugger or forest floor mulch

4 / Worms Are Our Friends

If you lay weed mat in your garden beds, you stop the natural cycle that keeps your soil healthy. Rainfall & nutrients are impeded by the weed mat to reach the soil.  Worms are unable to reach the surface of the earth when weed mat is put down, so over time worms leave the garden bed.  Worms are essential in aerating the earth, and without that function, a clay soil becomes compacted and during wet conditions more easily waterlogged.  These anaerobic soil conditions lead to plants to rot & die.

Conversely, when plants are growing in soil that is constantly enriched by organic matter in the form of mulch, or fallen leaves, compost, manure etc., worms are attracted into the soil where they aerate the earth (essential if you have clay soil) and leave behind their castings.  Worm casts hold moisture, which means less watering and the soil stays lighter and fluffier.  The soil’s microorganisms also thrive, breaking down the mineral matter into the nutrients that plants need to grow.

worms improve your soil

5 / Perfect for Pebble Pathways

Weedmat is perfect under aggregates like pebbles & shells in areas where plants aren't growing.

6 / Without a plant, there will be a weed

People have in the past used weedmat to reduce weeds in their garden.  They often find over time, the weeds end up growing through the mat making it virtually impossible to cleanly remove the weed, without breaking it and leaving the roots intact, ready to grow quickly back.  

The best way to reduce weeds is to plant 'preferable plants' that completely cover your exposed garden beds.  Groundcover plants are used by garden designers to creep along the ground and act as a carpet and barrier to weeds growing.  At Sculpt Gardens we often use plants such as Coprosma repens 'Poor Knights', Spanish shawl, Pratia angulata and Muehlenbeckia axillaris to do this job.

Next Steps

So, if you do currently have weed mat in your garden, we advise pulling it up, adding some garden mix and sheep pellets to enrich the soil, pop in some new plants that will grow and spread over the entire garden bed and finally lay a thick layer mulch.   

If you’d love some assistance in choosing those plants and groundcovers, don’t hesitate to get in touch with our expert team!


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