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Gypsum ClayBreaker is a soil conditioner improving soil structure, aeration and assists drainage and moisture retention. Find out below the other ways natural gypsum can benefit your garden.

Why apply ClayBreaker™?

What does ClayBreaker™ do?

  • Breaks up clay, loosens hard and compacted soil
  • Builds a deeper topsoil
  • Enables plant roots to penetrate deeper, resulting in strong plant growth
  • Improves soil drainage
  • Reduces root rot, moss and fungal diseases
  • Increases the absorption and availability of water, air and nutrients to plants
  • Improves moisture retention during dry conditions, reducing soil crusting and cracking
  • Enhances the effectiveness of fertilisers
  • Provides Calcium which strengthens cell walls making plants more resistant to insects and disease
  • Provides Sulphur, necessary for the development of green protein rich leaves
  • Enhances beneficial microbial activity aiding the composting process and decreasing unpleasant odours

And it’s a natural, non-toxic, organic mineral that is safe to use near children and pets. ClayBreaker™ is also pH neutral, which means it won’t burn plants or affect soil acidity if over applied.

Where can it be applied?

Where can it be used?
Beneficial for all lawn varieties, vegetables, flowers, citrus, fruit trees, shrubs and large trees including acid loving New Zealand natives, rhododendrons, camellias and strawberries.

 Is it safe to use on all plant and lawn varieties?
Yes, even on acid loving plants. ClayBreaker™ is pH neutral, which means it won’t burn plants or change soil acidity if over applied. There are no negative effects of over applying ClayBreaker™ making it your stress-free friend in the garden.

Is there anywhere it shouldn’t be used?
The benefits of ClayBreaker™ will be more limited on soil that is already free draining and well structured. ClayBreaker™ works most impressively on hard, heavy, compact soil and clay. Soils with a clay content of 30% or more respond particularly well to ClayBreaker™. Potted plants and raised beds will likely benefit if the soil or mix is compacted or poorly draining.

Plants in well drained soils will still receive the Calcium and Sulphur nutritional benefits from ClayBreaker™ but lower rates can be applied.

What is it made from and how does it work?

What is ClayBreaker™ made from?
ClayBreaker™ is a natural, non-toxic, environmentally safe, organic mineral CaSO4 – 2H2O Calcium Sulphate. It is processed into a fine premium grade powder form to enable rapid absorption and results.

How does it work?
ClayBreaker™, physically alters the structure of the soil. It breaks up heavy clay soils via a process called flocculation. This involves the readily available Calcium from ClayBreaker™ forming a bond with clay minerals to encourage the formation of small soil crumbs rather than large clods or impervious clay. This improved friability of the soil provides more pore space so that water, oxygen and dissolved nutrients can penetrate through the soil more easily to reach the root zone. Roots are also able to develop more easily and reach deeper. In wet months, ClayBreakerTM enables excess water to drain more effectively and in dry months it enables the soil crumbs to hold and retain more water.

ClayBreaker™ naturally contains 23% Calcium and 18.3% Sulphur, both are essential plant nutrients. Calcium strengthens cell walls making plants more resistant to insects and disease and Sulphur is an essential element necessary for the development and production of a green protein rich leaf.

Further technical information

How should it be applied?

How do I apply it/use it?
For best results dig ClayBreaker™ into the soil and then plant, or for established lawns and trees, spread on the surface and water in well.

For new lawns, we recommend either scraping off the topsoil (often this has already been removed in new subdivisions) and applying ClayBreaker™ directly to the clay areas, or spreading on the surface of the existing soil base and watering in well. (it will still work its way down through non-clay topsoil’s and improve the subsoil). You can then return any removed topsoil and sow the lawn seed or lay ready lawn.

When planting new trees, we recommend digging a hole twice the depth and twice the width of the plants existing root base. Spread Winstone Gypsum™ ClayBreaker™ in the hole and then plant the tree.

How much should be applied?
The amount that should be applied varies depending on where you are applying ClayBreaker™ and the quality or condition of your existing soil. Below details recommended application rates. There are no negative effects of over applying ClayBreaker™. It will not adjust the acidity of your soil or burn plants or lawns.

Application Application Rate Coverage per 8kg bag Coverage per 25kg bag
Hard, heavy, compact soil and clay Apply 1-3kg (4-12 cups) per m2 2.5-8m2 8-25m2
Lawns, vegetables, flowers, citrus, fruit trees, shrubs, large trees Apply ½ – 1kg (2-4 cups) per m2 8-16m2 25-50m2
Compost Apply 2.5kg (10 cups) per 100kg of compost 320kg of compost 1,000kg of compost


How often does it need to be applied?
For best results apply twice a year.

What time of year is best to apply it?
ClayBreaker™ can be applied any time of year. For best results we recommend it is applied twice a year in Spring and Autumn.

Problems with hard, heavy, compact soils and clay become more evident when there is either a lot of rainfall resulting in poor water absorption, surface drainage problems, root rot and moss, or very little rainfall resulting in soil cracking, surface crusting, hard unworkable soil and poor water, air and nutrient absorption. Therefore application of ClayBreaker™ before wet winter months and dry summer months provides the maximum benefit.

Health and safety information

Is it safe to use near children and pets?
Yes. ClayBreaker™ is a natural, non-toxic, environmentally safe mineral that is not harmful to people or animals, so there’s no need to worry.

ClayBreakerTM Material Safety Data Sheet

Are there any health and safety precautions that should be taken when handling ClayBreaker™?
ClayBreaker™ is manufactured from Gypsum; a natural, non-toxic, environmentally safe mineral that is not harmful to people or animals. The fine particles can, however, irritate lungs and eyes, therefore use of a safety mask and eye protection, such as goggles, is recommended when handling.

What should I do if I get it in my eyes, inhale or ingest it accidentally?
First Aid:

  • Eye contact: Flush thoroughly with water to remove particles
  • Inhalation: Move to fresh air
  • Ingestion: Call a doctor if discomfort occurs

How much do I need and where can I buy it?

What bag sizes is ClayBreaker™ available in?
ClayBreaker™ is available in 8kg and 25kg bag sizes.

The 8kg bag provides a lighter, easier to handle option for smaller gardening projects. The 25kg bag provides an economical option for larger areas such as lawn applications.

What do the bags of ClayBreaker™ look like?

Soil Life

What is the average coverage area per pack?
The amount that should be applied and therefore the coverage area per bag varies depending on where you are applying ClayBreaker™ and the quality or condition of your existing soil. Below details approximate coverage rates for the different applications:

Application Application Rate Coverage per 8kg bag Coverage per 25kg bag
Hard, heavy, compact soil and clay Apply 1-3kg (4-12 cups) per m2 2.5-8m2 8-25m2
Lawns, vegetables, flowers, citrus, fruit trees, shrubs, large trees Apply ½ – 1kg (2-4 cups) per m2 8-16m2 25-50m2
Compost Apply 2.5kg (10 cups) per 100kg of compost 320kg of compost 1,000kg of compost


Where can ClayBreaker™ be purchased?
ClayBreaker™ is available in all good general building merchants and garden centers throughout New Zealand

Product storage

How should ClayBreaker™ be stored once the pack has been opened?
ClayBreaker™ has been designed for improved solubility ensuring rapid absorption and effectiveness when applied to lawns, gardens and compost. This does mean it can absorb moisture so we recommend storing it in a closed bag in a dry environment.

Further Information

Who can I contact to get more information?
If you would like further information on ClayBreaker™ contact Winstone Wallboards.

Winstone Wallboards Ltd
PO Box 12 256
Penrose, Auckland
Ph: 0800 100 442
Fax: 0800 229 222