How To Lower Your Soil's pH and Turn Hydrangea Flowers Blue

In a nutshell, here is what you need to do when planning to grow blue hydrangeas.

• Test the pH of the area of the garden or yard where you plan to plant the shrub.
• Select a product to lower the pH if it's above a six.
• Follow the directions on the package (of whichever product you choose - some are listed on this page) for amending the soil.  Don't overdo it, and realize that it may take some time for the pH to change.
• If the plant is already in the ground, do not be overly aggressive with treatment as you could damage the plant.

Of course the flowers may be a variety of colors (including pink) if certain roots are feeding off the more alkaline parts of the soil.  The blue flowers will also fade and become various shades of pink, purple and even green, in my experience. 

You may want to consider growing your blue hydrangea in a pot, using store bought dirt, with peat moss, and lots of organic matter added.

Not all types of hydrangeas can have blue flowers. The type that has a changing flower color is the macrophylla. It gets it's name from the size and shape of it's leaves.  'Macrophylla' means long, or large leaves. 

To the best of my knowledge, this is the only type of hydrangea that will have blue flowers if it's grown in soil with a pH that is below six.

These plants are deciduous, and will have bare branches in winter.  Don't cut them down!  New growth will appear along the stems in Spring.

Hydrangeas of this variety will usually have roundish, ball-shaped, flower heads.  The exception is the lacecap, which has a more flattened looking flower and appears to be only partially in bloom, when in fact it is in full bloom. 

The paniculata variety has flowers that will not change color due to soil pH.

From what I've read about amending the soil with some type of sulfur to lower the pH, it must be added carefully and then worked well into the soil at a depth of at least six inches.  This can be tricky when trying to add it around a shrub that is already in the ground.  Doing it before planting would be the best option.

If you want to change the soil type in a large area, know the dimensions before buying sulfur.  There should be charts at the store for figuring how many pounds of sulfur to buy.  The sulfur reacts with bacteria already in the soil.  The bacteria breaks down the sulfur to increase acidity and this process can take weeks or even months.

I've never grown a hydrangea indoors.  I don't know what would happen to it over winter - would I have a bunch of leafless sticks to look at?  Does it have to stay in a cold place?  If it's inside, will it bloom again next year? 

If you know the answers to these questions, please leave a comment!

Organic Gardening - How to Lower Your Soil pH
Learn the basics of pH levels and how to fix them for your growing needs.

How to Adjust Soil pH For Your Garden
Charts and information on raising or lowering garden pH for growing things in general.

Changing Soil pH
About pH, and why it should be optimal for growing certain vegetables. How sulfur works to lower pH and charts to determine how much will be needed to do so.