Hydranga... how do i keep its colour?

Hello everyone, i'm new to this site and relatively new to gardening. I have a blue hydranga and would like to know how to keep it blue, apparently it depends on the type of soil to which the colour changes. All help/advice will be most welcome.
thankyou

 

Hi Ronster68 - If I can add a tag onto your post please I would like to know the answer to this question which hubby and I argued over the other day. I say you can buy a pink hydrangea and it will stay pink whatever you do. He says that if you put it into acid soil it will eventually turn blue. Now, as you all know, I'm a dodo when it comes to plants but I am digging my heels in on this one and say if it is pink to start with it will stay pink and that if it is blue to start with and the soil is not acid it will turn pink.

Thank you one and all and especially Ronster68 who has raised this point. :D

 

Hi Ronster68 & kryssy, Blue hydrangers in acid or limey soil to keep them blue you can use a compound of Aluminium sulphate

 

Funny you should bring this up. I have just been reading a monograph on Hydrangeas. The colouring of H. macrophylla cultivars is covered at length in it. As far as I can understand, blue plants in acid soil, generally produce a better blue than they do in neutral to alakline soil. Pink plants produce a deeper colour in alkaline soil. White plants produce white flowers no matter what the soil. However, both pink and blue plants can produce different shades of flower at the same time. Also the plant often does not show its true colours until a few years after planting from a pot to the soil. Pink flowers only fade to pale they do not go blue, no matter what.
Final point, do be careful with adding aluminium to your soil, it damages the hydrangeas roots in large amounts. Aluminium phosphate is better than A. sulphate by the way, but it is much harder to get hold of. Does that cover it?

 

Well, whoopsiedoo. I'm right. Hubby owes me. Thank you so much Palustris.

We must have mostly acid soil here as there are blue hydrangeas everywhere. I have two pink and one blue and the pink ones stay pink - just like I said.

AND - I must give you a proper welcome to the forum Ronster68. I should have done that in the beginning. Don't worry, not everyone is a mad as me.

:D

 

Hi Ronster68 and welcome, rather than add aluminium to your soil just pop to your local garden centre and buy some Hydrngea colourant. David.

 

Er, David, Hydrangea Colourant as sold by G/C's is Aluminium sulphate!

 

Thankyou everyone for all your advice. Will be getting my soil testing kit out and then its business!!!
until my next problem..............tara x

 

This link explains it all (I think).

hydrangea colour change

John.

 

The monograph I used to answer this was "Hydrangeas" by Toni Lawson Hall and Brian Rothera. Perhaps my reading of what they say is at fault, but they seem to say that changing a pink to a blue is not really possible. Perhaps it is in pot culture, but in the garden then not? Very odd.

 

I used to have a pink one and over a few years it changed to lilac and started going slightly blue, I have acid soil. I dug it up 2 years ago and gave it to a neighbour cos it does'nt fit in with my tropical scheme, in her garden it has gone back to pink completely.

 

Doh, is my face red Pal. David.

 

This is pasted from Heronswood Nursery, my favorite Hydrangea source. Recall reading this years ago--point is only certain species of Hydrangea are affected by soil pH.

No matter their nativity, Hydrangeas in general are woodland understory plants and thrive in moist but well-drained soils amended with organic matter (humus, leaf mold, compost).
Most species tolerate a range of pH conditions. However, the H. macrophylla and H. serrata cultivars are unique for their flower color being determined by the relative acidity of the soil: a pH below 6 (acidic) will usually produce flower color closer to true blue, whereas a pH above 6 (more alkaline) will produce flowers more pink. Add aluminum sulfate to soil to make flowers bluer or add lime to soil to make flowers pinker (apply to plant root zone in late autumn or early spring). If your soil is already extremely acidic (pH 5.5 or lower) or extremely alkaline (pH 7 or above), it might be very difficult or impossible to change pH sufficiently to change the flower color of your hydrangea.

 

I Remember my Father telling me when i was a lad (and that was'nt yesterday) :( He would add rusty nails or bolts into the roots of the Hydrangeas to change their colour :skp:. dont know if this is an old wifes story.but when i was digging part of the garden a month ago i discovered a old rusty ships Rivet
it was encased in rust and i planted it with the Hydrangea (a little bit of Nostalgia). looking out the window it is growing great and it is (to my eye) RED. music .