Gypsum will improve and maintain the health of your garden plants. It is good with flowers, vegetables, trees, lawns,
in the greenhouse and on the compost heap. Gypsum helps in two ways. It improves soil structure and it supplies calcium
and sulphur (essential nutrients).
Gypsum is a natural, non-toxic mineral certified for use in organic production. Gypsum is not harmful to children or pets
and even when applied at very high levels it will not damage your soil or plants.
See Gypsum Material Safety Data Sheet (PDF 158Kb).
In new gardens the original topsoil is usually removed before building leaving only the subsoil clays. Although a thin
layer of topsoil is sometimes put back on top this is usually not deep enough to be of much use. Also, the immediately
underlying layer of subsoil will have been severely compacted by workers and vehicles. Even in established gardens, heavy
(high clay) soils are commonly very compacted by foot traffic and do not drain well.
Gypsum helps by combining fine particles into larger aggregates giving the soil a more friable and crumbly structure.
The benefits are:
- Better drainage
- Reduced compaction
- Less crusting
- Easier working (easier to incorporate compost).
Plants are susceptible to 'wet feet' problems (especially bulbs, lavender and rhododendrons). All plants grow better in
a soil that is loose, crumbly and free draining. Gypsum gives:
- Better root penetration (better access to nutrients and water)
- Reduced root rot and better breathing
- Essential nutrients calcium and sulphur
- No change in soil acidity (pH) so gypsum is safe around acid-loving plants like rhododendrons, strawberries and camellias
(lime will damage them).
Gypsum helps aerate compost allowing fungi and bacteria to do their work quicker and reducing unpleasant smells.
Gypsum also raises the compost's nitrogen content, for, in the presence of gypsum, the ammonia released by bacteria
converts to ammonium sulphate (a fertiliser) instead of being lost to the air.
Gypsum can be applied by hand at any time of the year. Conveniently, 1 kg of gypsum has a volume of about 1 litre so you
may find it easier to use a volume measure. Gypsum can either be sprinkled on the soil surface or gently worked in to get
a faster response. It is good to water it in afterwards.
