Tuesday, June 29, 2010

Hydrangea's "Flower Power" wanes in our urban garden

After 6 weeks of our enjoying their vibrant beauty, the Hydrangeas in our garden have begun their departure for the season.

Sadly, the jar you see has the last remaining vintage blue and green blooms from our garden.

There are still a few pink.....

And a scattering of blues

Next to Peonies, Hydrangeas are at the top of the list of my favorite flowers. Fortunately, for me, they grow very well in our region. Their bloom cycle is from early spring to autumn. However, the cycle here ends when the summer temperatures soar above 100 degrees. I'm looking forward to planting Peonies this coming fall in time for the 2011 season.

This is one of the 2 climbing Hydrangea vines we planted last summer which began its crawl up the lattice last.

I recall reading somewhere a horticulturalist quote stating this particular species sleep the first year, creep the second year then leap the third year. We are looking forward to next year's leap.

Finally, I found this interesting read from HydrangeasHydrangeas on how to change the colors of your Hortensia.


Pink  color change

For hydrangea blooms to be pink, the plants must not take up aluminum from the soil. If the soil naturally contains aluminum, one must try to keep it away from the hydrangea's system. Following are a few tricks that might work:
  • Add dolomitic lime several times a year. This will help to raise the pH. Shoot for a pH of about 6.0 to 6.2 (If it goes above 6.4 hydrangeas may experience an iron deficiency). Since hydrangeas take up aluminum best at lower pH levels, raising the pH will help to keep the bluing effect of aluminum out of the hydrangea's system.

  • Use a fertilizer with high levels of phosphorus. Phosphorus helps to prevent aluminum from creeping into the system of the hydrangea. Choose a fertilizer close to the ratio of 25/10/10 (Phosphorus is the middle number).

  • In areas that naturally produce blue hydrangeas (soils with aluminum), consider growing pink hydrangeas in large pots. If hydrangeas are grown in pots, it would be best to use soil-less mixtures, since these mixes would probably not have aluminum in them. In a pot, it will be much easier to control the requirements for growing pink hydrangeas.
Blue  color change

To obtain a blue hydrangea, aluminum must be present in the soil. To ensure that aluminum is present, aluminum sulfate may be added to the soil around the hydrangeas.

Authorities recommend that a solution of 1/2 oz (1 Tbsp) aluminum sulfate per gallon of water be applied to plants (which are at least 2-3 years old) throughout the growing season. Important: Water plants well in advance of application and put solution on cautiously, as too much can burn the roots.

To make the aluminum available to the plant, the pH of the soil should be low (5.2-5.5). Adding aluminum sulfate will tend to lower the pH of the soil. Another method for lowering the pH is to add organic matter to the soil such as coffee grounds, fruit and vegetable peels, grass clippings etc.

If the soil naturally contains aluminum and is acid (low pH) the color of the hydrangea will automatically tend toward shades of blue and/or purple.

The choice of fertilzer will also affect the color change. A fertilizer low in phosphorus and high in potassium is helpful in producing a good blue color(25/5/30 is good. Potassium is the last number). Superphosphates and bone meal should be avoided when trying to produce blue.

After stating this with much certainty, I hasten to add that it is virtually impossible to turn a hydrangea blue for any length of time if it is planted in soil with no aluminum and that is highly alkaline (chalky). One would have to be very diligent in keeping the soil properly conditioned as stated above.

Perhaps the best idea for growing blue hydrangeas in an area with alkaline soil would be to grow them in very large pots using lots of compost to bring the pH down. The above suggestions for bluing would also work for a potted plant. Reduce the strength of the Aluminum sulfate to 1/4 oz per gallon of water. In a pot, it will be much easier to control the requirements for bluing.

One last suggestions for those who are serious about this process. It is important to have your water tested so that it will not "contaminate" the soil that you have so rigorously balanced. The pH of the water should not be higher than 5.6.

Planting hydrangeas near a concrete foundation or sidewalk will often affect the color since the pH of the soil may be raised considerably by lime leaching out of these structures, making it difficult to obtain blue.


MaryBeth said...

I can't believe your hydrangea will grow from pots. I would think they would become pot bound or too dried out in the urns. Is this possible to the specific type of hydrangea that you planted?

Katie@LeBeauPaonVictorien said...

What beautiful color hydrangeas you have! I love the blue/green ones especially.
I have to work very hard to get my hydrangeas to be blue (or semi-blue!)....luckily for me, where I live, they will bloom all summer long and into fall.

Janie's World said...

Hi Julio, your hydrangeas are gorgeous! I'm interested to see how your peonies grow. I'm pretty sure they won't grow down here but they are so beautiful. You've motivated me to give them a try. I'm sure I'll have to special order them, I've never seen them at any of the nurseries.

Anonymous said...

Just found your blog & LOVE the hydrangeas. I can only guess you are cutting them when they are still soft. When they 'ripen' (almost dry) they should last longer, sometimes months.
Of course you could always plant more for a steady supply!

BTW the climbing hydrangea sometimes takes longer than three years to establish roots, but once it does, stand back!

Bill said...

Hi Julio,
The hydrangeas here in West Tennessee appear to have peaked as well and are in slow decline. They're still beautiful, but that vibrant color and lush fullness are no longer evident. Do you cut yours and use them in dried arrangements? A neighbor uses her dried (mophead) hydrangeas to decorate her Christmas tree every year and the effect is wonderful!

Hope you and yours have a very happy 4th!