Pink Annabelle clones currently on the market are a shade of pink that does not change to blue in acidic soil. Tweaking the soil pH alters the shade of pink only a little, not much.

A-l-l colored macrophyllas can change if their soil pH is altered: from blue to shades of pink if you add garden lime; from pink to shades of blues if you acidify the soil.

White blooms cannot be altered by changing the soil pH but they do normally change in color as they age and mature.

I thought that was nonsense. When I look at my pink ES some of the blooms are lavender with a touch of blue. So her explanation didn't make sense to me. I guess she was confused because she does sell the pink Annabelle clones.

What is the best way to change the color? Are there natural ways like coffee grounds ( I read that somewhere)

It's all soil chemistry. Easier in some cases than others. Buffering capacity.

Only macrophyllas (including serratas in this group) have an ability to change color in response to soil conditions. Paniculatas and arborescens (Annabelles) only change color in response to aging of the flower - whites will always be white - and this includes the macs - except taking on rosy red tones or sometimes green as the flowers age.

And some macs - pinks especially - are not very responsive to soil conditions and hold their color rather firmly. 'Glowing Embers' and 'Pia' are examples of those. They tend to remain rather firmly pink regardless of conditions. Even in the rather acidic soil conditions of the PNW these stay pink. Otherwise, it all depends on cultivar......some change readily, others not so much.

So she was part right :-) Most blue flowered bigleaf hydrangeas can change colors but you cannot necessarily make the same statement for all pink flowering cultivars.

I have 2 Endless Summers which started out blue, but were pink the very next year. Last fall I added what I thought was a lot of aluminum sulfate to the soil, but I should have done it just before blooming, since this spring the blossoms were showing pink, not blue. I watered in more aluminum sulfate, and now there are some blossoms showing blue. Fascinating.

Gardengal thanks for clearing that up now I can see what she was talking about. Lelia you watered the aluminum sulfate in? How? What product did you use?

The flowers are blue when the plant takes in aluminum and pink when it takes in iron. Acidic soil by itself won't guarantee blue flowers, there has to be free aluminum also. Most add Aluminum sulphate to get blue flowers, but if your soil already has plenty of aluminum and the flowers are pink strictly because of ph, be careful because too much aluminum can be poisinous.

Posted by DDhydrangea none (My Page) on
Fri, Jun 24, 11 at 11:04

Gardengal thanks for clearing that up now I can see what she was talking about. Lelia you watered the aluminum sulfate in? How? What product did you use?

I used Greenall True Blue aluminum sulfate, which is granular. I spread it around the roots as if it were fertilizer, then watered. Didn't measure, I'm just going by blossom color to tell me if it's enough. Now the older blossoms are pink, some are half-pink, half-blue, and the newly opening ones are really blue, so it seems to work pretty quickly.

I wasn't planning on doing anything this year since the main flowering is done. I'll get a soil testing kit to be safe..........just good to know that my pink can change to blue if I want it to.

Right now I'm trying to find the heart to prune them since it rained they are flat on the ground, next year I want stronger stems (and blue flowers).

Update, I forgot about the soil testing kit. I added aluminum sulfate, 1 tablespoon in a gallon of water. I have 3 endless summers planted close together in the same flower bed so I gave them 2 gallons of water/sulfate. After doing some research I also purchased Miracle Grow for acid loving plants 30-10-10, 1 tablespoon per gallon of water.

They look fine, nice and healthy with no adverse effects from frost damage in march. How often should I administer the aluminum sulfate / Miracle Grow for blue flowers? Is this where the soil testing kit comes in?