Image from InfraStructure magazine – Australia
Many seeds have mechanisms that inhibit germination until the right circumstances are present to give them a good chance of germination and survival. Until that happens, they lie dormant in the soil – often for long periods of time. For a long time, it was thought that many seeds needed fire to trigger them to grow. That is often true for the seed carriers – for example a cone may require fire before it opens up and shoots out its seeds. But that is not the end of it. The seeds then wait for rain but it is not the moisture that is important, it is that the rain soaks the charred vegetation, takes some of the chemicals into a solution and these chemicals break down the seed coat, enabling germination.
Regeneration by fire
It is thus not surprising that many of the seeds that grow in regions that depend of fire for regrowth, need a smoke treatment in order to get successful seed germination. While this sounds like a fundamental understanding of plants, this chemical dependence was only recently established – like in the late 90s and early 2000s. Yup this is cutting edge science in the horticultural industry. It has enabled plants to be brought to market that were almost impossible in the past.
This is also impacting treatments to help restore native vegetation in some regions. Again, it was though that fire was just killing off the invasive species, but they did not understand that the smoke was also helping to break seed dormancy.
What I don’t think is yet fully understood is what those chemicals are. For examples, does smoke from a Pacific NW forest fire help to germinate seeds from Australia or South Africa? I hope that I will be able to establish that over time because right now I am having to import smoke from down under to help with the germination of Proteas and other species that I would like to start growing. That smoke is often trapped in filter paper or vermiculite. I have read many papers that suggest that not all plants when burned produce the right chemicals. The scientists are still trying to ascertain which chemicals are important and if all seeds need the same chemicals.
Applying it elsewhere
This is not just something that pertains to exotic plants. Researchers in the country are trying to find out what helps Penstemon’s germinate better as well as many other American natives. These are important questions for the nursery industry who are trying to bring new hybrids to market or lower the costs associated with growing native species.
The companies down under are clearly making a killing on smoke export, so I hope that I can find a way to make my own smoke that I can use for germination. Wish me luck!