Scarification trial

Many seeds such as acacias have very hard seed coats and require a physical method to allow water to enter the seed and break dormancy. Such a process is called scarification. This can sometimes be done with sandpaper, using nutcrackers or nicking with a knife depending on the type of seed. Soaking in hot (not boiling water) for up to 48 hours is another method. Seeds must be sewn directly after the soaking period and must not be allowed to dry otherwise they die.

This trial was to compare germination rates of Acacia verticillata and Dianella tasmanica when seeds had been scarified by soaking in hot water for 24 hours compared with seed that had been given no prior treatment.

10 seeds of treated and 10 seeds of non-treated A. verticillata were sewn in different punnets. The same was done for D. tasmanica. This occured on the 23rd April.

Photos of A. verticillata punnets taken on 19th May, about 4 weeks later, with top punnet containing treated seeds and bottom punnet non-treated :

After 6 weeks (non-scarified on left and scarified on right) :

Note the strike rate for scarified seed is 8 out of 10, whilst non-scarified is 2 out of 10.

This shows that germination rates are higher when Acacia verticillata has been scarified.

At 4 and 6 weeks no Dianella tasmanica had germinated, as is expected with the time it normally takes to germinate.

reference : RHS propagating plants pg 53-4