I’ve read of various people trying numerous ways to successfully germinate tagasaste seeds. From direct planting to boiling in water for one minute or scarifying the seeds and planting. I too have made endeavours to get hard coated seeds such as acacia and tagasaste seeds to germinate through various means and I’ve settled on a process that has a really high percentage of germination.
I place a quantity of seeds, say a teaspoon, into a small ceramic ramekin and boil the kettle. I pour the water directly over the seeds to half of the ramekins depth. Then I leave it to cool. Typically I do this overnight as it sets the process up for regular attention as you will see. I set this all up on the kitchen bench so that I can check them regularly and the sink and kettle are close by.
In the morning I drain off most of the water and check the seeds. One or two may be swollen and have turned a dark brown colour. These seeds are ready. I pick them out and put them into another ramekin with just enough water to keep them wet. They will continue to swell in this water. I boil the kettle and pour it over the remaining seeds. In the evening I will check them again, pick out any swollen, brown ones and place them into the second ramekin with the others and repeat the boiling water on the rest and leave overnight.
This can take over a week for most, if not all of the seeds to reveal themselves as ready to plant. The second ramekin of seeds that are ready will gradually collect a decent quantity of seeds that I will sow into some sand with a little potting mix or material that will retain a bit of moisture such as coconut coir or saw dust.
Repeating this process, by the end of the week you should have most of the seeds ready. You may notice some in the holding container have started to germinate and may have their root appearing. There is usually a bit of lenience to the process. I may not change the cold water and add boiling each morning / evening if I am busy, but just the sitting for extended time in the water contributes to their readiness to germinate I have come to think.
If you have tagasaste trees growing nearby I would recommend taking a sample of soil from underneath and adding it as topsoil to your propagating pots to introduce the microbes that will benefit the seeds. I’ve not always been able to do this, but just taking samples of soil from underneath trees with thick, natural leaf fall has worked too.
Seeds that I have put through this process about a week and a half ago are now coming up in their pots after the recent sun and rain showers. Another couple of weeks and I hope to plant them straight out to make the most of the rain and to get them established before summer.