Why is a gardener's thumb singled out for especial greenness?

Where did that idiom come from?

  • 11
    In the UK, we say "he has green fingers". Jul 4 '11 at 15:02
  • @Neil Coffey: You're quite right, which is why I as another UK speaker thought there was something odd about OP's question in the first place. But as usual, I expect US usage will end up swamping the English-speaking world in the end. Jul 4 '11 at 15:26

As this NGram shows, thumb was once less common than fingers. For some reason people have never been particularly keen on thumbs or finger, but they get used too. As Neil Coffey commented, fingers remains more common in British English.

Green hands do in fact exist too, but sometimes simply alluding to the inexperience of general-purpose unskilled employees. I think thumb wins out in the end because the singular is a bit simpler, and thumbs don't have so many other associations that might confuse the imagery.

My chart combines US and UK usage figures, but looking at the patterns for each country separately makes it clear that US thumb and UK fingers became far more dominant in their respective countries from about the 1940s, with little change in usage figures for whatever word was being used on the other side of the pond. I think this may be a result of increased commercialisation of "domestic horticulture" at the time. This probably led to a proliferation of books, magazines, local clubs, etc., and these by their very nature would be far more likely to encourage standardisation around an easily-recognised term.

Thus it may be little more than a fluke that the US standardised on a different term - if neither was particularly well known before, either would be happily embraced by commercial and social networking interests. But standardisation would be very much encouraged thereafter, whichever form happened to have taken the early lead.

Obviously a gardener spends a lot of time handling plant material, much of which is green and might therefore stain one's digits. Since the metaphorical usage is so transparent, it could be re-coined many times. It would normally be understood on first hearing, and often passed on by the hearer, so the expression could have had multiple opportunities to both germinate and thrive.


  • The aspects of the answer are much more interesting than I thought they would be. I'm impressed.
    – Daniel
    Jul 4 '11 at 16:14
  • @drm65: It may be that unwanted association with the distressing condition white finger will help push out the British usage in this mechanised age. Strange how the US plumped for thumb so decisively, though. Jul 4 '11 at 21:27
  • 1
    The Word Detective has an interesting theory which may explain the nGram. "In the period immediately preceding and during World War II, one of the most popular programs on BBC radio in Britain was called “In Your Garden.” [...] Eric Partridge suggested that this program might have popularized both phrases, and that “green thumb” was actually a reference to the very old English proverb “An honest miller has a golden thumb.”"
    – user1579
    Jul 4 '11 at 23:51
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    @Rhodri: Sounds plausible to me. Using NGram to look at the US side of things I saw lots of references to magazines and gardening clubs called or including the words Green Thumb. Radio is part of the same thing. It's all about what we might call a "craze", which could explain why each side of the Atlantic used their own preferred word so exclusively - they were hearing and reading it a lot. Jul 5 '11 at 0:17

The thumb and forefinger are generally used to pinch back plants. Considering the special function of the thumb resulting from its anatomical difference (it is opposable to the other four fingers of hand and has two phalanges instead of three), it is necessary to achieve the objective. I think that the use of thumb rather than other fingers or the whole hand in this idiom is to emphasise its importance in relation to the task.

  • 3
    Wouldn't both the thumb and fingers be green then because the thumb ain't much help without the fingers.
    – Mitch
    Jul 4 '11 at 18:28
  • @Mitch They obviously would, but the thumb could do the work with any of the remaining four which is not as easy vice versa. Jul 4 '11 at 18:35
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    Your speculative etymology doesn't explain why in BrE, people use 'green fingers'.
    – Mitch
    Jul 4 '11 at 19:44
  • @Mitch: There does remain the question of why US usage so decisively and contrarily opted for thumb when fingers was already dominant in the old country. I think partly they just liked the sound of the word, plus there are so many idiomatic usages involving finger they also liked something that stood out (like a sore thumb! :) Jul 4 '11 at 21:36
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    @FumbleFingers: A comparison of two separate NGram graphs American vs British shows that 'green fingers' was established well in both countries, but that somehow in the US during the WWII years, 'green thumb' started to take over wildly. The answer as to 'why' there would really go towards answering the OP.
    – Mitch
    Jul 4 '11 at 22:05

In addition to the previous comments, I have another theory. Upon removing false nails recently I discovered my nails/skin had dark green patches or stains. Unwilling to think I was turning mouldy, I turned to the internet.

I discovered ‘Green nail syndrome’ a condition where bacteria have been able to thrive in a warm, moist environment. Aside from being a common occurrence in false nail wearers, it also made clear that anyone whose hands are regularly submerged in water/moist environment or in contact with soil or animals, might experience this at some point. It would then seem to make sense in terms of regular gardeners. Just a thought.

enter image description here

Pseudomonas aeruginosa is a common bacteria that can cause disease in plants and animals, including humans. It is found in soil, water, plant, pets, skin flora, and most man-made environments throughout the world. When it grows, its waste produces pigments that impart the green color of chloronychia (the technical term for green nails caused by p. aeruginosa bacterium). Common Nail Disorders: Chloronychia aka "Greenies"

  • If you include some of the citations from the article you found, this could be turned into a good answer.
    – Skooba
    Aug 17 '18 at 14:18
  • Thank you for your comment. Unfortunately, it was just a general internet trawl. However, anyone who requires more information simply need only put Green nail syndrome (or similar) into a search engine. Aug 17 '18 at 14:39
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    I do appreciate original and plausible ideas, and references support your idea. But for the idiom to become popular, the manifestation of this infection had to be well known. If it occurred only sporadically, the idiom would not have been easily recognised or understood. I think, see also FumbleFingers' answer, the cutting and handling of green vegetation that causes the fingertips to stain (when a gardener does not wear gloves) is a more likely reason for its natural coinage. Moreover, in Italian the idiom is avere il pollice verde which is literally "to have a green thumb".
    – Mari-Lou A
    Aug 17 '18 at 15:36
  • @Mari-LouA: I wonder how old the Italian idiom is.
    – herisson
    Aug 18 '18 at 3:16

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