Tomato seeds exposed to aerated solutions (10, 50, or 100 parts per million concentrations) salicylic acid and gibberelic acid produced seedlings with enhanced vigor, as measured by germination percentages, germination speed, and seedling growth rates.
So what does this mean in real gardening terms for increasing tomato seedling vigor?
1) You can mess about with salicylic acid (aspirin) all you like but don’t mess with gibberelic acid. The gibberelic acid concentrations are minute and a single part per hundred out will do very nasty things to seedling growth. We used to use this in the greenhouse for plant growth control and increased flowering (it’ also sprayed on apple trees for the same reason) and you really didn’t want to make a mistake (measured with eye droppers) with this one. You used to be able to get GA from GardensNorth (on their site – go to contact-us – germination corner) if you’re really determined to use it on seeds. Most of the time, it is only the really hard to germinate seeds that receive this kind of treatment.
2) The concentration of salicylic acid is low at 10 -100 parts per million so you’re going to have to the math on figuring out how much acid your aspirin brand contains and how much water to use.
In the “old days” when we would root up hard to root plants, we’d recommend folks put a sprig of English Ivy or Willow in the rooting water as these plants produced this acid in the process of forming their own roots. Plants would root up faster with a sprig of this plant than without.
Only soak in Salicylic acid for 24 hours for maximum benefit.
The research does not point out what influence (if any) this increase seedling vigor has on harvest yields although one would assume a positive one. If I were guessing, I’d go with earlier crops. This can make it worth the trouble for growers who love to get that early premium price but not so critical for home gardeners.
I don’t mess about with this stuff but I include it for your experimenting.
“Effect of Hormonal Priming on Germination and Seedling Vigor of Tomato,” Aamir Nawaz (Institute of Horticultural Sci- ences, University of Agriculture, Faisalabad, PAKISTAN), et al. AHS Annual Conference paper 2010.