Scarification

Scarification is the the process by which a plants seed is mechanically altered to replicate and speed up the natural process a seed would undertake on its way to germination. The seeds of some of some of our native species, such as Kowhai (Sophora ssp.) are often impervious to water and gases, thus preventing or delaying germination.

Scarification also applies to the weakening or removal of the hard shell on stone fruit (drupes).

Mechanical scarification

The most common type of scarification is mechanical scarification.

With mechanical scarification, the hard shell is physically opened to allow moisture and air in. Seed coats can be filed with a filed, rubbed with sandpaper, nicked with a knife or even cracked gently with a hammer. I find a set of nail clippers is perfect for just taking a fine nick out of most seed, as all you are aiming to do is to allow the seed access to all the environment has to offer.

Hot water scarification

Hot water scarification is another common method in which seeds are placed in warm water, generally overnight to allow the heat from the water to kick start the germination process. In the case of out native Kowhai (Sophora species) a combination of both mechanical and hot water scarification I find is the best method of achieving fast and even germination.