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Hob Nails (Guest post from Chris Beardshaw)

Last post 19-04-2008 10:51 PM by Ariadne. 11 replies.

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  • 16/12/2004 12:17 PM
    • admin
    • 20 Nov 2003
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    "My favourite practical example of gardening folklore is a tale passed on from my grandmother who would bury a hob nail boot under hydrangeas to change their colour from pink to red. She always kept my grandfathers old boots for the purpose. This works due to the iron released into the soil as the nails in the sole and heal of the boot rusted." [i]Posted on Behalf of Chris Beardshaw.[/i]

  • 17/12/2004 11:29 AM
    • ken69
    • Norfolk UK
    • 23 Nov 2004
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    Must have got it wrong...thought it was to turn it blue..or is that COPPER nails.Must admit I like it red or blue not in between.Never really keen on the climbing hydrangea either..looks so dead in the winter.Regards Ken

  • 17/12/2004 12:51 PM
    • P Stick
    • North Wales
    • 24 Nov 2004
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    I agree with Ken68 that CB has it wrong as it is for turning the flowers blue if you are on an alkaline soil. Iron sulphate, copper sulphate and also I think but not certain, aluminium sulphate all do this. Certainly the copper works better than the iron.

    P Stick
  • 18/12/2004 07:30 AM
    • William
    • 24 Nov 2004
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    Hi Ken, I agree with you, the iron is needed to turn hydrangea macrophyllia blue. Put them in limy soil and the lime prevents them form absorbing elements (like ironoxide?) that makes them go blue (possibly needed for stimulating a hormone in the plant) I could have my chemistry and biology a bit wrong though. But I'm quite certain the colorchange is from red(pink) to blue....

    Happy Gardening, William
    (Netherlands)
  • 18/12/2004 12:31 PM
    • P Stick
    • North Wales
    • 24 Nov 2004
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    Since my last reply, I searched around and came up with the following lifted from BBC Suffolk website in June last year. "4. During the summer as I travel around Suffolk I often see Hydrageas in gardens that have been changed from Pink or red to Blue. Well if you have any of the traditional Hydrangea hortensia type in your garden that are pink or red, these can be changed to blue if you wish. Now is the time of year to water the plants with the blue colorant (aluminium sulphate). This causes no harm to the plants, but will change the flowers from pink or red to blue. This colorant is available for sale in most good garden centres." I think Chris' folklore is his 'Old Mother's Tale' and needs correcting but does he believe it himself? Somehow I doubt it.

    P Stick
  • 18/12/2004 01:22 PM
    • William
    • 24 Nov 2004
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    Hi P Stick Some more additiona research, the color changing trick works only with hortensia's that have the pigment "delphinidin 3-monoglucoside". "The hydrangea takes up aluminum ions which are toxic to most other plants (and animals). When the soil is neutral to alkaline, the aluminum ions are bound to other ions like oxygen or phosphates. The hydrangea cannot take up these complex compounds. When the soil is acidic, the aluminum ions are freed and readily absorbed by the roots." (Much more info on the following link: http://www.killerplants.com/weird-plants/20020117.asp) It could be that the rusting of ion increases the acidity of the soil by binding oxigen atoms and freeing H+ ions....

    Happy Gardening, William
    (Netherlands)
  • 18/12/2004 03:57 PM
    • P Stick
    • North Wales
    • 24 Nov 2004
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    Hi William - what a good link you gave in your reply and there's another great link on there to the Missouri Botanical Gardens. They also have a good plantfinder. Perhaps you should bury the hob-nailed boots with the old gardener still wearing them to reduce the soil's PH and water with an aluminium sulphate solution after a few months.

    P Stick
  • 19/12/2004 11:53 AM
    • William
    • 24 Nov 2004
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    If it works for pushing up the daisies .....

    Happy Gardening, William
    (Netherlands)
  • 20/12/2004 04:48 PM
    • ken69
    • Norfolk UK
    • 23 Nov 2004
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    It was a 'test'....no doubt we will be called upon to appear in a future edition of Gardeners World.

  • 08/04/2005 10:06 AM
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    Hobnails, boots; the bogweevil has his reservations. Colour in the range pink to blue is dependant both on hydrangea cultivar and on the availability of aluminium in the soil, largely determined by soil pH reaction. Aluminium is responsible for the blue flower colour in hydrangeas. In acid soils it is readily available to be taken up by the roots, but in neutral and alkaline soils it is unavailable to the plant. The flowers of a particular cultivar will be blue at a low pH of 4.5–5, changing to mauvish, then pinkish with increasing pH, to turn pink at pH 7 7.5. Where there is no obvious chalk or lime in the soil, it may be possible to induce flower colour to change from pink shades to blue by using one of the proprietary hydrangea bluing or colorant preparations, obtainable from garden centres. These have to be applied well in advance and applications continued for some time. heavy doses defoliate the plants. It is a waste of time attempting to induce blue flowers if the soil is chalky or contains lime. Instead, improve the pink or red colour by applying a dressing of ground limestone or chalk at 75–100g per sq. m (3–4oz per sq. yd) during the winter.

    Beware the bat-eared bogweevil
  • 16/04/2008 01:16 PM
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    my grandparents used to pour the tea-leaves and dregs from the bottom of the tea-pot round their hydrangea in the summer. It would start of pink then end blue, I guess becuase of the acidic tannins in the tea.

  • 19/04/2008 10:51 PM
    • Ariadne
    • Contemplating on the compost heap
    • 05 Apr 2008
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    ...........& how the monster, Beardshaw doth laugh at all the garden weevils busting their guts with indignant argufying !!!! 

    Sitting, spinning threads of stories & weaving the colourful strands of life.