How to smoke treat Australian native seeds for better germination, a step by step guide including materials and tips for success.
Over the years, Australian native plant species have adapted to the bushfires that ravage parts of the country. Oftentimes you see the beginning of life beyond the aftermath, with plants emerging out of the blackness and sprouting with new growth. This marks the evolution of native plants in their ability to detect when it is safe to germinate and start the regeneration process.
If you’ve ever considered growing Australian native plants from seed, chances are you would have been informed that the seeds require smoke treatment to aid in germination. One such example is the bush tomato (Solanum centrale) also known as desert raisin.
Why Smoke Treat Native Seeds
As per the work of nature, the application of smoke breaks seed dormancy and results in increased germination rates. There are many ways to smoke treat native seeds which include the following:
- making your own smoke water by carefully burning hay and dried leaves, soaking their ashes in water then fine straining the liquid before soaking the seeds.
- soaking seeds in store-bought smoke water and soaking seeds in a 9:1 water:smoke-water solution for 12 hours.
- using commercially available vermiculite that has been smoke-treated which you would place on top of the newly sown seed raising mix
- using smoke paper from garden centres and placing it on top of the seed raising mix
How to Smoke Treat Native Seeds
One of the easiest ways of smoking native seeds requires a BBQ with a lid, straw or hay and dried leaves, and a plastic takeaway container. Here’s how to do it:
1. Spread the seeds in one layer in a takeaway plastic container.
2. Place the hay and dried leaves on the grid of a kettle BBQ.
3. Using a lighter, carefully set the hay and leaves on fire. Note: You are not lighting up the BBQ, only the leaves on top of the grid.
4. Gently blow out the smoke until it’s just smouldering.
5. Place the seeds in the takeaway container beside the smouldering hay and cover the lid of the BBQ. The smoking process should go for approximately 20 minutes. However, the smoke will go out and you will need to open the BBQ and repeat the process a few times during the 20 minute period.
6. The seeds will be coated with the smoke chemical and will have a dark coating. a Store the smoke-treated native seeds in a container until ready to use.
Tip: It is preferable to smoke treat the seeds when you plan on sowing them, however, I have been told that they can last for approximately one year when stored properly in a cool, dark and dry environment.
After Smoke Treatment
After smoke treating the bush tomato seeds, I stored them in a small plastic container. A few days later, I sowed some of the seeds in seed raising mix that was pre-moistened to avoid over-watering the sowing medium and rinsing out the coating. I used a spray bottle to keep them moist with the occasional bottom watering.
Australian native seeds take a long time to germinate and it pays not to give up too soon. In this case, germination was super fast. I sowed the bush tomato seeds in November and they germinated in 14 days. Germination rate was less than 50% but I was thrilled with the results.
At the time of writing, I have three bush tomato plants in my garden. One is in the Australian native raised garden bed and the other two are back up plants in small containers.