If I believe the species benefits from this method I always say so in the descriptive text.
Many other plant species may also benefit from it but if I don’t personally suggest it, then that’s because I don’t know for sure. Or failing that I ran a side by side trial and there was no benefit VS just planting in sandy well-draining Soil Mix as per normal.
It is very important to note that this only works well on species with very hard shells that have a very long natural dormancy, or species that rely on bushfires to germinate. If you do this with a species that has a thin shell or has not evolved to these unique conditions then you are just making seed soup…
Boiling water will cook and kill delicate species very reliably so please read the descriptive text on product pages, or if you are feeling all scientific run a side by side trial that includes an untreated control group.
Side by side trials with a control group are awesome, I do them constantly, and if that sounds like fun I also suggest you checkout my GA3 and Smoke treatment pages too!
Anyway, back to the HWT. This simple method does two things.
- The first is heat.
The reason why it’s good is that heat cooks and changes things like oils and proteins into slightly different chemicals that are more easily absorbed. It’s the main reason we cook food. When this happens within the seeds these newly created chemicals send signals, some of those signals are the cue to sprout.They do this because in a harsh environment like Australia many plants rely on bushfires to clear out all the competing plants, remove the leaves from the big trees giving the seeds more sunlight access. They also enrich and fertilises the soil all at the same time. The dormant seeds then only have a few weeks to take advantage of this specific little niche so they have to hurry up and shoot RIGHT NOW! If they had of sprouted any earlier they would not have survived, and they have a hard seed coat to make sure they can just sit and wait for year after year, decades in some cases.
- The second thing HWT does is leaching and dilution.
The heat widens and opens up the cell walls, and the hot water dissolves chemicals in the seeds. A large amount of water and a small amount of seeds then dilutes and weakens these chemicals. The only job of these naturally occurring chemicals is to stop a seed from shooting too early, so once they are dissolved and removed, then the plant immediately shoots. This only happens in the wild when there has been a fire, then heavy flooding rain.
The fire removed competition and the rain washed all the topsoil mulch and ash, along with the seeds into a nice moist low depression, the ideal place for it to be. Now it knows it has a good chance of success, far better than any other time in its life, so it immediately springs into action as fast as it can!
Now you know why it works so well, the method is easy.
- Boil the kettle.
- Pour your seeds in a bowl.
- Let the kettle boil and as soon as the bubbling stops pour two cups of very hot(but no longer boiling)water on the seeds.
- Wait about 8hours. If more than half of the seeds have still not expanded, swollen, changed from a black to a chocolate brown colour, or have a pronounced white tip, or small splits in the shell, or any of the above, then just dump out the water and repeat from Step 1 again.
- You have now noticed that half or more of the seeds have expanded, swollen, or changed from black to a chocolate brown colour, or have a pronounced white tip, or small splits in the shell or any of the above.
At this point, they are ready to rock!
- All you need to do now is plant the seeds in a nice well draining Sandy Soil Mix as per normal, water only when the soil surface is dry, cross your fingers.
Hot water treatment is not necessary for growing every single Acacia species or hard-shelled plant species out there. It often reliably shortens germination times, but at the same time it also slightly lowers total germination success % over time.
For example, it may mean you only get 40% germination within a month using HWT. The other 60% actually died from the process which doesn’t sound great at all…
Without HWT you may get 90% germination or even higher which sounds really impressive.
BUT, it is very important to note that this impressive 90% germination may also take 10years or more for every seed to shoot which is a hell of a lot more time than most folks are willing to invest.
4/10 right now, or 9/10 in ten years time…
Using HWT on suitable species you can have plants fully growing to maturity and setting millions of seeds themselves, in the same amount of time it takes an untreated packet of seeds just to germinate.
Well worth considering.