aluminum sulfate

[bigvictu]

I have a customer who wants her hydrangeas to turn blue. Should I put some down now and in the spring, or will putting it dowm in the spring be early enough to turn the flowers for summer. Thanks for any info.

[GDK]

There is no exact answer to this because it depends on your soil condition's pH. If you really want to do this right, then sell her a pH test first. I was just having this conversation with someone today and this is what we do in the arboretum where I work. We do an application of elemental sulfur and aluminum sulfate in both the spring and the fall. We have a relatively high pH soil, so we have to lower the pH fairly drastically. The elemental sulfur is important in lowering the pH of the soil and we want to lower the pH to a range of 5.2 - 5.5. The reason for this is because you can apply all the aluminum sulfate you want, but if the pH is relatively high, the plant will not absorb the aluminum sulfate. At 5.2 - 5.5, this is the ideal range for aluminum sulfate and it will be readily absorbed. The other guideline is to not apply too much aluminum sulfate because it can quickly raise to a level of toxicity and kill the plant. Seeing that you are from South Jersey, the guidelines for your applications are most likely to what I just listed because of the sandy soils. Also, another point to note is that not all hydrangeas will reach the brightest blue because it depends on the plant.

[bigvictu]

Ok I'll do a quick PH test they are nikko blues.

[GDK]

Okay, sounds good. They should become a beautiful bright blue.

[danf]

Have they been flowering consistently?

Nikko's flower on old wood, meaning the buds have to live through the winter in order to bloom the next year. I planted Nikko's at our house in Indiana back when they were a relatively new variety to that area and the thinking then was they bloomed on new wood. :( The first couple of years they bloomed fairly well, but the last couple of winters were pretty harsh and I think we had ONE bloom the last two years between 3 shrubs.

GDK gave you some good advice on checking pH. Getting a quality soil test done will be of long-term benefit, contact your local extension agent for information on where to send a sample to.

[bigvictu]

bountiful beautiful pink flowers.

[GDK]

If they are pink, then definitely get a soil test because you have quite a ways to go with the pH.

[MuirView Design]

Vic, we put it on our Endless Summers at my house in the spring this year and got blue flowers. I even put it on my Lady in Red Hydrangeas just to see if it would have an effect, and sure enough I had blue lacecaps. I would wait till the spring if I were you. When the plant is transferring a lot of energy and nutrients as it is starting to push open the bud sites. Winter could work to, I just know spring worked for me.