Thursday, July 3, 2008

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?


16 comments:

themanicgardener said...

Fascinating. I have no hydrangeas, though now I'm tempted to get a couple as pH indicators. I do have typically alkaline western soil, but also more than my share of spruce and pine. So this spring, I used the lower layers of spruce needles as organic matter for some of my soil. The fact that they take forever to break down is (I think) good in this case, because they'll continue to add loft in my clayey soil longer than if they just broke down in a year. I haven't done a follow-up pH test; when I do, I'll post it.
--Kate

Rosehaven Cottage said...

I'm so glad you wrote this post! I knew about the acidic soil but didn't know that it was really the aluminum that does the bluing. I've been wondering why my usually white hydrangea has blue tinges this year. It's along the picket fence by a neighbor's driveway so I suspect that it got something on it or in the soil. Now I think I'm closer to solving the mystery thanks to your very knowledgeable post.

Hugs,
Cindy at Rosehaven Cottage

P.S. Do camelias do the same thing? I've got a weird red camelia that's had blue edges on the petals of the first blooms for the past two years.

Cinj said...

Wow, I never knew that either. If that's the case all of my hydraneas should have blue flowers.

Shady Gardener said...

Kylee,
I don't have hydrangeas, but rhododendrons and azaleas like acidic soil, also. I lay my boy scout Christmas wreaths under the bushes, as well as pine needles and evergreen prunings. :-) I haven't tested the soil, but it hasn't hurt them!

Muum said...

I have alkaline soil, too, from the heavily limestone soil! I thought about the pine needles, but when I ran it by our county extension agent, he was dubious, so I didn't try it. I do try to water it now and then w/ acidic fertilizers, and with a bit of vinegar in my water. Not anything systematic, though. I will be interested to see how your experiment turns out.

Lisa at Greenbow said...

Your hydrangeas are looking mighty nice Kylee.

Kylee said...

Kate ~ We have heavy clay here and it seems all I do is amend it. It's much better than it was a few years ago, but can still use some work. I haven't formally tested my soil for its pH, but I'm told we do have typically alkaline soil here and my hydrangeas have always been pink before, so I'd say it's true.

Cindy ~ I don't know if my post has helped or not, but thanks!
I don't know about camelias either, since we don't grow them here. I wish we could, because I just love them and have admired them on your blog and on others. There are so many pretty ones!

Cinj ~ So ARE they blue? Remember, it's the aluminum that makes them blue, but the soil needs to be acidic for the plant to be able to absorb enough aluminum to blue up the blooms.

Shady Gardener ~ I've got one azalea and I mulched it heavily last winter because I have trouble getting them to even survive. This last one, which I planted last spring, made it through and had some gorgeous red blooms this spring. I don't think I put the pine needles around that though, just some of the hydrangeas.

Muum ~ So far, it seems to be working, as 'Bailmer' is blooming blue. The other hydrangeas started opening up late today, enough that I could see some color, and one is going to be pink. That is part of the group that I did not mulch with the pine needles.
I didn't add any aluminum to the soil, just did the pine needle thing. That was the only thing I did differently. So who knows...but it seems to have done something!

Lisa ~ Thank you! I will say that they are looking about as good as I've ever seen them right now.

Yolanda Elizabet said...

I garden on clay too and my hydrangeas are naturally pink. I like pink, as you know, so I've never felt the need to turn them blue. I'm going to buy a few hydrangeas this year but they will be white.

Your hydrangea Lady in Red looks stunning and I'm happy for you that you've managed a very good blue on your hydrangea Endless Summer because sometimes you get a very wishywashy colour of light blue and pink mixed together. Not good.

Do you have the oak leaved hydrangeas too?

Kylee said...

My dear Yolanda Elizabeth, all your vacationing seems to have done something your vision. It may have been all that eye candy you've been taking in lately! In any case, my friend, as it says toward the end of my post, yes! We do have an oak leaf hydrangea! Just planted this year, so I'm anxious for it to grow and flower. I got it from an online nursery, so it's small.

I actually don't mind those blended pink/blue blooms, but prefer the blue. I like the pink, too, so if they don't turn blue, that's fine. It's all good!

Kara said...

I love your blog and I always learn something when I come to visit! Thanks!

Garden Lily said...

Kylee - Fascinating, I've always loved the pink colours, but mine have "faded" toward blue over time. It's all a matter of perspective.

I've "tagged" you on my "Flowers and Weeds" blog. I hope you'll have time to join in the fun.

Cinj said...

Good question! I can't remember what we planted last year and we also have two new ones. No blooms yet, so I'll have to wait and see. I'll let you know!

Ewa said...

Hello Kylee,
I love hydrangeas. I really do. there is one problem their open buds (no protecting sjhells in winter) very often freeze in our climate zone (6), so I decided to grow hydrangea paniculata: colors vary from white via limegreen to pink. Flowers are big, long lasting and the plants are very hardy, up to 4 zone. Best I can reco is Tardiva and Limelight. Kyushu is little bit too lacy.
Your hydrangeas are great and pictures also in beautiful way.
Thanks for sharing.
Greetings,
Ewa

mel said...

Years ago I lived in an apartment in Raleigh that had a huge, old hydrangea bush by the back patio. Curiously, the bush bloomed both blue AND pink! While digging around the roots to plant other flowers, I found a stash of old rusted AA batteries buried in the roots of half of the bush. I guess that is one way to add acid to the soil?

Anonymous said...

I enjoyed reading about your roses and hydrangeas. I have played with changing their colors over the years and had some interesting results going from pink to light ;avender to blue and even one that turned a deep purple. You made me wish I had taken note now so I could remember what I fed them to get each color!

brenda aka Zanymuse

Amanda said...

You ever notice how as soon as you discover something new it seems like you get snowballed with it? I was just at a nursery yesterday and they were discussing the virtues of pine needles. Then a coworker said out of the blue later that afternoon she was going to try them. Then I come to your blog today nad here I find a post on pine needles...hmm, I'm not sure about them myself. But I'm really interested in what you have to say about them. Thanks!

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