The Pine Needle Experiment

I love blue flowers. Every time I bought a hydrangea, it was the blue color that drew me in, with the exception of 'Lady in Red' and 'Variegata.' But of course, with our generally alkaline soil, the second year the hydrangeas bloomed, they bloomed pink. Pink is nice, and I still liked my hydrangeas, but I longed for blue flowers on them.

There are several ways you can manipulate the soil to make it more acidic, which produces blue flowers on the hydrangea. Actually, it's not the acidic soil directly that encourages blue flowering, it's aluminum. But in order for the plant to make the best use of aluminum, the soil needs to have a pH of less than 5.5. Acidic soil enhances uptake of aluminum, much like our bodies need vitamin D in order to absorb calcium.

You can add aluminum sulfate to the soil by watering them with a solution of 2 tablespoons dissolved in a gallon of water. Make sure the soil is moist first, before watering with this, or you could burn the plant. Sulfur lowers the pH of the soil, as do pine needles, pine bark, oak leaves, or peat moss. No matter what the name of the hydrangea, such as 'Blue Nikko' or 'Pretty in Pink', all have pretty much the same chance of being pink or blue, depending on the soil.

You'd think with all the oak trees we have here at Our Little Acre and several pines, that we'd have acidic soil. We have sulfur water, too, so with these things combined, logic says we're likely to be acidic. But we're not. The pink hydrangeas were proof. So I decided to try something last fall, to lower the pH around the hydrangeas. I mulched some of them for the winter with pine needles.

The hydrangeas are beginning to bloom now, and it would appear that my plan worked. The ones that grow inside the gazebo have not yet begun to bloom. These I didn't mulch with pine needles, so I expect those to be pink, as they usually are. The blue ones are located under a huge oak tree and I mulched them heavily with needles from the large pine tree we have. Dad also donated some needles to my cause.

Endless Summer^® 'Bailmer'

I've also got Endless Summer 'Blushing Bride' and it is all-white and loaded with blooms right now. I got it last summer shortly after purchasing 'Bailmer', so we'll see if they both continue to bloom all summer, as they're supposed to.

Endless Summer^® 'Blushing Bride'

While you can blue the blooms of 'Lady in Red', it's not recommended for this particular cultivar, as they feel they aren't as attractive on this plant as the pink - 'they' being the University of Georgia and Michael Dirr, who developed it. I didn't mulch that one with pine needles so it's blooming pink and pretty now.

'Lady in Red' is so named because of its unique red stems, as well as its blooms and leaves, which age to a shade of burgundy. In the fall, the leaves are stunningly beautiful.

We planted a small oak leaf hydrangea this year called 'Snow Queen.' It will have white blooms, so no soil manipulation there. We'd seen lots of them at Garvan Gardens in Hot Springs, Arkansas, and they were just gorgeous, so I wanted at least one here. It's too small to have blooms this year, but I look forward to maybe having some next year.

Have you tried to change the color of your hydrangeas? How successful were you?