Hydrangeas

[Mosha]

Are these flowers native to Thailand? My dad used to grown them in the UK, putting old one penny pieces in the roots to make them turn blue. We have 2 here given by a friend, one is blue and one pink. Perversley I tried the coin trick, but it us under the pink one.

Edited February 12, 2008 by Mosha

[sbk]

Nope, but they do grow here. I haven't had much luck with mine, I had a nice one growing but went home for a month, it didn't get watered and it died

Mine preferred shady areas, without alot of direct sun, seemed to wilt by the end of the day if it got too much sun.

[meandwi]

They need cold in order to bloom. Most growers have refridgerated rooms to produce buds. You can try to trick the plant by feezing a few small blocks of ice and placing them over the roots every day for a week.

I recommend buying a pink Ixora plant. Nice clustering flowers and blooms all year.

Meandwi

[sbk]

Ixoras are wonderful plants, I agree. The native white one (although taller) smells wonderfully. As do the taller dark pink ones. Dwarf ixora, often used for hedging have no fragrance, but are still lovely to look at.

Dok Khem in Thai

Here is the pink:

and the white:

[sbk]

I have to add that I have never heard of a chilling requirement for hydrangeas and thought that rather, they were very not cold tolerant. I do realize they need a cool period but refrigerator cold?

Regardless, mine bloomed for several years before it was killed by underwatering.

[Mosha]

Of the 2 we have. The blue one seems more sun tolerant, I have moved the pink one into shade and it is doing better.

[chownah]

I have no experience with hydrangeas but I read in a couple of places that the color depends on the pH of the soil so you should be able to choose the color you want by adding stuff to the soil around them to adjust the pH...to get a basic soil (high pH) you would use lime...I don't know what would work to get an acid soil (low pH) but soils here are often naturally acid...adding sawdust would tend to make the soil acid but it would have a tendency to tie up the nitrogen in the soil if overdone so I guess it would be a bit risky....would vinegar do it?...don't know.

[sbk]

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.

Source: hydrangeashydrangeas.com