Can you learn to read your plants via smell?

Discussion in 'Advanced Growing Techniques' started by Sanez, Jun 13, 2018.

  1. Is there anything I can learn from smelling my plants each day? Or does vision tell you all the same information? I've noticed changes in smell here and there, but can't really tell what it means. Have you learned anything here about your strains?
  2. I learn when to change my carbon filter :laughing:
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  3. Smell can tell u u are in home stretch. I have found it to be a guidance to close to harvest time. If u go to far u will loose that and ur buds are degrading

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  4. Been trying lots o strains; I am beginning to smell the genetics.

    Yes.. the change smells from green foliage to sweat weed to hard core dank. Oh crop day is going to be stinky, so is the trim. Then you cure and the smell changes again. I think my house still smells from when I trimmed. My wife's friends decided to have a picnic in the backyard instead of coming in the house (lol).
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  5. #5 Sanez, Jun 13, 2018
    Last edited: Jun 13, 2018
    Heh. Yeah, so I did mean something a bit more subtle than the smell of veg versus flowering versus ripening. I meant something higher-dimensional, such as being able to roughly detect some set of deficiencies, or even the presence of some broader issue. For instance I've heard you can smell root rot. You may also be able to smell the plant's chemical response to certain environmental stresses (e.g., heat, dying leaves, or broken stems), or to certain pathogens/fungi/molds/pests.

    I don't know much about plant biology, but I understand there is a great deal of chemical signalling involved -- although our noses haven't evolved to have all the right olfactory receptors. This varies per person (e.g., women on average have more olfactory neurons than men). Maybe one day, some people coming from a long succession of cannabis cultivators will have many of their senses finely tuned to the plants' needs. Similar to how our vision has evolved according to the statistics of natural scenery. lol.
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  6. Aside from root rot, which just smells like any anaerobic rotting organic matter, I doubt human olfactory senses are developed enough to detect such things. For one this would require a good deal of experience smelling all these kinds of situations (deficiencies etc) which you would normally do your best to avoid in the first place.
    IMO unless you have a lab or some arrangement where you could smell plants with various maladies on a daily basis i don't see how anyone could actually train themselves, assuming one could even detect such changes in smell.
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  7. Well, someone with a big grow room, who checks in on it every day for 20+ years, will gain a great deal of experience. Repeat this for 100 or so generations and maybe you have a winner, lol.

    There's also plenty of "unsupervised learning" that goes on in our brains. Our perceptual systems seem to adapt and self-organize to the statistics of our environments (see article in my last post). There isn't a need to know what the smell means at first. The brain just needs to learn how to disambiguate the smells that carry different information. Once this is tuned finely enough, such that your olfactory system encodes/separates some of these different signals, you could in theory recognize at a higher level which smell means what by using your sense of vision together with your other experiences. This latter kind of learning can occur with only a single exposure (called "one shot learning"); ever had a smell that took you back immediately to some prior time and place and experience, even though you only smelled it once before?
  8. This also reminded me of this popular science talk:

    Our perceptual systems are much more capable than we sometimes give them credit. There is a lot of room to grow, with many differences between us in how we each perceive our own world. For instance I use my sense of hearing more than other senses relative to most people, but I also hallucinate sounds occasionally. My vision isn't very good, but I've noticed I can smell subtle differences in my plants. I just don't know what those differences mean, and probably never will in this life time. ;)
  9. Also related: The Reasons Behind That Pleasant Fresh-Cut Grass Smell ...


    Basically that smell of freshly cut grass is actually the smell of chemicals being released by the grass, as a distress signal. This isn't unique to grass, but it's much easier to notice by virtue of the sheer volume of grass!
  10. What reason would a plant have to signal a nutrient deficiency? All these smells produced by plants cost resources to make.
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  11. #11 Sanez, Jun 13, 2018
    Last edited: Jun 14, 2018
    Nutrient deficiency was just one idea. Others were "environmental stresses (e.g., heat, dying leaves, or broken stems), or to certain pathogens/fungi/molds/pests", which may be more useful for a plant to signal.

    But, to answer your question, the plant wouldn't so much be signalling the deficiency itself, but perhaps something correlated with a stress response. Or, even more simply, one might smell the absence of the good healthy smells. In other words, there may not be some associated "cost" beyond whatever the plant is already trying to produce (trichomes, essential oils, etc) and the lack thereof.

    It would be interesting to take something like an electronic nose (example) and collect a bunch of self-labelled data (from visual observations), and train a support vector machine (or similar) to see what kinds of observations can be learned from smell in theory. It's too bad cannabis research is not all that active, otherwise I'm sure someone would have tried this already.
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