Multicolor Hydrangea
I had someone pose the question to me, “Can I really change the color of the bloom on my Hydrangea bush by burying nails around it?” The short answer is yes. Hydrangea plants (mostly the H. macrophylla varieties) are very sensitive to the soil type. The blooms are strongly affected by high and low pH levels.
Not all hydrangeas change bloom colors, though. Newer varieties such as the Annabelle and PeeGee will only have white blooms no matter how much you sing to or curse them! But the older varieties will dance for you if you treat them right.
The rusty nail principle is an interesting one. The iron from the nails, old sawblades, tin cans, add acidity to the soil which helps the blue flower appear. But, it is not the acid that changes the color, it is aluminum that does that. The Iron helps the plant to absorb the aluminum that you will be adding to the soil. You can bury some aluminum nails, or use aluminum sulphate or even better but harder to get, is aluminum phosphate. That is what makes them really blue. Singing will cheer them up, but they will still be blue! J If you want to take them back to pink, just add lime to the soil and they pH will neutralize. All this changing is making me tired!
Changing the pH does not happen overnight. It will takes months, or at least a couple of bloom cycles to change. Even though it would be cool to watch the existing blooms change color right before our eyes! I watched a magic show the other day, that would have been cool to see. Anyway, start burying those nails and wear gloves if you dig the plant up to transplant it!
Planting Hydrangeas in really large pots is an easy way to control the pH, BUT the plant will get root bound very quickly, and drinks a TON of water, so prepare yourself. You can use pine straw mulch to help keep the soil acidity high.
Happy Hydrangeas
#1 by Garden Gnome on July 20, 2009 - 5:17 pm
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This is really a neat idea! I am so going to have to try it. I found your blog through Twitter so am following you there. I'm gardengnome1. I thought you might be interested in blotanical.com which is a great way to meet other gardening bloggers worldwide. You would fit in well there
Take care and happy gardening!
#2 by KevinPigg on July 21, 2009 - 10:43 am
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Without knowing your exact situation, I suggest you use a bloom booster fertilizer, Aluminum Sulphate (or Phosphate) fertilizer, and this winter use Triple Super Phosphate. Lightly prune them back in Aug. and then don't touch them again until after they bloom next year.
#3 by Jennifer Milele on July 20, 2009 - 9:42 pm
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Kevin, I replied on FB, but incase you don't see it I'll put it here too. I have two hydrangeas. 1) is a hydrangea bush, it got one bloom this year. the first one in four years, I was so excited. 2) a climbing hydrangea I planted 9 years ago and it has NEVER bloomed. I have tried rusty nails, acid food and all sorts of things and nothing has worked. any suggestions for either of these? Jennifer Milele
#4 by KevinPigg on December 17, 2009 - 1:18 pm
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What is your pruning schedule?