We discussed last year about the hot water treatment, a very easy to apply germination method which can successfully replace the use of scarification for the Fabaceae species. However, it is hard to say if it would be effective for all species and if all species will germinate at room temperature afterwards.
In addition, I will provide answers to few common questions and plates with seeds images for all species/genera I personally tried/try with this method.
How much the seeds should/will swell after a hot water treatment?
It depends on the species, the size and shapes of the seeds varies greatly, but usually the seeds can increase in size 2-3 times than the original size. Sometimes you may notice a ‘dramatic’ change in the seeds aspect/size (ex. Lupinus breweri).
Is it possible that no seeds will swell after 1 treatment?
Yes, it can happen, repeat again (for ex. Senna hebecarpa, Oxytropis, Trifolium seeds are slow to react).
How much time should the seeds remain in water?
Usually the next day you will see if the seeds have swollen (and how many), but to be sure you can keep them in the water for 2-3 more days (change the water daily).
In extreme case, seeds may even start to germinate in water after a while! (Hedysarum, Thermopsis).
Will all the seeds swell at once?
No, in the majority of cases after the first treatment only a few seeds will swell. Sow the swollen seeds after each treatment and repeat for the others (2-3+ times).
How soon will the seeds germinate?
It varies greatly with the species, some will start to germinate in few days, others will take a longer time (for ex. various Baptisia were slow to germinate).
Fabaceae – Hot water treatment 2019; notice the increase in size and the differences between species; all were germinated at room temp. afterwards
Current trials:
Fabaceae – Hot water treatment 2020; seeds aspect after 2 treatments. For each species notice seeds still of normal size and also swollen seeds.
