Introduction: Changing the Color of Hydrangeas

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Have you ever had a blue hydrangea turn pink? A reader named Carol emailed me asking why her gorgeous blue hydrangea was turning pink the year after she planted it. I had this happen with 1 of my client’s Endless Summer Hydrangeas so I know exactly what’s happening. If blue is your thing, here’s how to change the color of your hydrangeas.

Step 1:

This is the intense shade of blue that many people desire. You may have bought your hydrangea as this color (the grower controls this) only to have turn pale or to pink.

The change in color of your hydrangea is due to a reaction to the pH of your soil. Yes, as I always say, the health of your plants is dependent on the health of your soil and in the case of hydrangeas, it determines the color. If your soil is more alkaline, your hydrangeas will be pink or pinker. If your soil is more acidic, then they will be blue or bluer.

Step 2: Watch the Video for the Instructions

Step 3:

A beautiful blue lacecap hydrangea. As you can see blurred on the edges, some of the flowers are lavender pink.

A pH of 7 is neutral by the way. If you want to check out the pH of your soil, here’s the link to a simple soil test kit as well as a meter .

These hydrangeas that I’m referring in this post are shrubs by the way. I changed the color of my client’s Endless Summer Hydrangea back to blue with garden sulfur. I worked it into the soil in a circle halfway between the drip line and the base of the plant. Make sure the soil is moist when you apply it and water it in well when you’re done.
I did this 3 times a year in temperate California because the hydrangeas have a long bloom time here. If you’re in a cold climate, you may only have to do it 2 times a year. Be sure to follow the directions because even though this is an organic element, you can easily overdo it. Don’t desire a navy blue hydrangea and dump a whole bag in on the 1st application!

Step 4:

More pink & blue flowers on the same hydrangea, this time a mop head.

Things To Know:

* This doesn’t apply to white hydrangeas; white hydrangea stay white.

* It’s much, much easier to change the color of a hydrangea from pink to blue rather than blue to pink.

* I never fertilized hydrangeas (only composted them), but if you’re feeding them with a fertilizer that’s high in phosphorous (phosphates), then stop. It’s a deterrent to the color change.

* Applying the sulfur as a powder is a slow process when it comes to changing the color – don’t expect immediate results. However, the results are long lasting but it will need to be applied in subsequent years to keep the color blue (ish).

* If you know your soil is more on the alkaline side, then it’s best to apply the garden sulfur upon planting blue hydrangeas.

* For obvious reasons, it’s much easier to change the color of hydrangeas in containers than it is in the garden.

* You will probably never get your hydrangeas back to that intense blue they were. In the case of my client’s hydrangea, the flowers turned pale blue & lavender blue.

As I say in the video, I’m a big proponent of working with the soil you have and planting plants appropriate for that soil type. That being said, if you must have blue hydrangeas and your soil is on the alkaline side, have at it with the garden sulfur.

May your garden be a rhapsody in blue!

Happy gardening,

Nell Foster

PS: Here’s 1 of my early blog posts which shows you How I Prune Hydrangeas