Touching Tomatoes

Photo by Gayla Trail  All Rights Reserved

They say that lightly brushing your hands against tomato leaves stimulates a growth hormone in the plant encouraging radial (aka stockier) growth. I’m still searching for a study that supports this but I chose to believe it regardless, which is why I spend some time each morning lightly touching my young tomato seedlings. I’m sure the extra attention helps them grow healthier too. Plus it just smells good.

Washing your hands before touching the plants is advised, especially if you are a smoker or come into contact with cigarette smoke since it is possible to transfer the tobacco mosaic virus to tomatoes through touch. Some people are mildly allergic to tomato leaves so its probably a good idea to wash your hands after contact too. And that concludes all the hand wash advising I am going to deliver for the next year. Because advisories freak people out and I am more interested in encouraging confidence than inspiring fear.

My little plants are all coming along well. I’ve got about 10 seedlings transplanted to larger pots and more waiting to be repotted. They’re not going to go outside for another month yet so they have lots of growing to do in the meantime. It’s interesting to note how differently each variety grows from the next right from the get-go. ‘Black Pear’ and ‘Purple Calabash’ are the leaders in height with ‘Czech’s Bush’ still reigning supreme as the stockiest plant I have ever grown.

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Gayla Trail
Gayla is a writer, photographer, and former graphic designer with a background in the Fine Arts, cultural criticism, and ecology. She is the author, photographer, and designer of best-selling books on gardening, cooking, and preserving.

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24 thoughts on “Touching Tomatoes

  1. So this is my first year with my seedlings–I think I over sowed the tiny peat pots. There are a good 5-7 per pot. Should I thin back all but one? They are finally getting some true leaves as well. How will I know when to put in a larger pot?


  2. I think touching then simulates movement that would naturally occur outdoors in a breeze, and everyone says tomatoes like a bit of air movement. Makes sense that it would make them stockier, so they can stand up to the “wind”.

  3. I took a Master Gardener class this spring, and one of our “Old Masters” said that he does this to make the tomatoes stronger and also shorter. Anecdotal, of course, but he’s been growing tomatoes for 40 years.

  4. I’ve been doing that with my tomato seedlings and they are coming along nicely. One question I have though is that one of my seedlings is popping loops of roots up through the soil. Should I just cover them back up with soil or does this mean they need a bigger pot? Not sure what to do with it but it has little flowers now so I don’t want to kill it as these are my first tomato seedlings ever.

  5. buttercup: I for one am not above it.

    Andrea: It’s hard for me to tell because I don’t know what you’ve got them in but my guess is if they already have flowers they need to be in bigger containers.

    Kristy: Because the peat pots are so tiny you should thin back to one per pot. Don’t try to separate them at such a young and fragile state because you will only disrupt the roots and risk killing all of them. Instead, cut the others off with a pair of scissors. Brutal and hard to do but with so many in a pot you are going to end up with lots of unhealthy plants or none at all.

  6. I don’t have any scientific evidence for this either, but if you look into it the word “thigmotropism” may be relevant.

    Plants can sense touch and grow differently based on it – tendrils will grow toward things they are touching, and roots will grow away. Supposedly wind causes plants to grow stockier (you can also set up a fan to blow on your tomato plants).

  7. It’s always been my understanding that touching plants and providing good air movement promote stronger, stockier stems (how’s that for alliteration!) Even trees that are staked too long grow taller, weaker trunks.

  8. The scientific name for it is thigmomorphogenesis :)

    In an unnaturally still environment (like a greenhouse), plants tend to grow taller and weaker. This is sometimes seen in nature, in very sheltered spots.

    A light breeze, or a soft touch, reverses the effect so that they grow stockier.

  9. Ciao Gayla-

    Did you get Czech’s Bush from me? I totally forget if that was one I gave you. It’s a very stocky plant, one that I grew on my driveway last year in the wading pool. It’s fairly early as well. Remind me next time I see you, I’ve got a lot of dwarfs and determinates you might want.


  10. I have finally had success with growing tomatoes from seed! So far they are only little sprouts but is still exciting- now if the peppers could just sprout…

  11. Has anyone else noticed that when you touch tomato plants, and then wash your hands, the water running down the drain is bright yellow? Or is this just some weird chemical reaction that happens with Manitoba water?

  12. Touching your tomato leaves has a similar effect to the hardening process where plants go through the process of acclimating to a new environment and go through a process of toughening up. A farmer I know recommends that a week before taking one’s tomato plants outside for hardening off, that one should set up a fan to lightly blow against the leaves of the plant. This has a similar effect to touching the leaves, except for a more sustained and gentle ‘handling’ effect (i.e., this process makes the plant stronger and more robust).

  13. Hee hee hee. My poor little seedlings suffered some while I was on vacation for ten days, so last night I spent a quarter of an hour petting and singing to them, a little ditty I made up called “Eat a leaf.”
    Glad to see I’m not the only one…

  14. laura is completely right. “fondling” simply breaks the cambium slightly inside the plant, stimulating growth of cambium, causing thickening by increasing the width on both sides of the cambium, depending on what the cell divides for. a much larger scale example is a tree that is tied will sometimes grow much wider above where it is tied, due to the iwnd being able to sway it back and forth

  15. Mike: I know touching simulates the effect of wind on the plant but I have always read it triggers the release of growth chemicals/hormones… I’ve just never been able to find a document that states what those chemicals are.

    I will have to look further into your explanation… and then reacquaint myself with certain biological terms… although I do recall what cambium is.

  16. for more “breaking” fun, try lightly twisting lower stems of tomatoes over 12 inches (you’ll feel a small snap). this will break the vascular system inside which reheals much larger and able to transport more food and water through more xylem and phloem. be careful when experimneting with this method because it is fairly easy to break stems (although I have puts so many splints on plants, I’m not terribly concerned). have fun and be careful.

  17. Direct rainfall on tomatoe plants make them wilt,what information is there on this?Is it the acid rain or just the water on the leavs?

  18. tonyb: Who said that? Tomatoes are rained on. It happens and is fine. But watering the leaves with a hose or watering can is a problem. It encourages fungal and viral growth and often results in stressed out plants that are suffering from soil drought but too wet up top.

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