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Blue/Pink Hydrangea

Discussion in 'Organic Lawn Care' started by Smallaxe, Sep 6, 2008.

  1. Smallaxe

    Smallaxe LawnSite Fanatic
    Messages: 10,082

    We put in some hydrangeas the other day and some were blue, others pink, and of course the white.
    It is said that blue comes from an acid soil, whereas as pink comes from an alkaline soil. Makes sense and probably true.

    Question is:
    Would you prepare the planting hole for the acid loving plant, differently from the alkaline loving plant to enhance the best color?
    If so - how?
  2. phasthound

    phasthound LawnSite Fanatic
    Messages: 5,143

    You can adjust the color by peeing in the hole. :)
  3. cudaclan

    cudaclan LawnSite Member
    from Zone 5
    Messages: 152

    No. Well-drained planting locations and sun – partial shade is required. Certain species require mulching (zone 4/5) during the winter. Deadhead when flowers fade. If planted near the street, road salting and compaction (winter snow) will deteriorate/kill performance. Hydrangeas are a staple in a typical “Cape Cod” (saltbox) home setting. It is imperative to know your species as horticulture practices vary from species to species.
  4. Plant Buyer 83

    Plant Buyer 83 LawnSite Member
    Messages: 176

    It is much easier to control or alter the pH (which directly affects flower color) of the soil in a container than it is in the ground - as one would think.

    It is easier to change from pink to blue than it is he other way. Changing a hydrangea from pink to blue entails adding aluminum to the soil. Going from blue to pink means eliminating aluminum from the soil or taking it out of reach of the hydrangea (making it unavil or harder for plants to get to - see below a higher pH makes it harder for the plant to take up Aluminum).

    The first thing I would do is get a soil sample done to see what the native soil shows and make choices based off that.

    Ax - I have read your posts before and you seem very knowledgeable - but keep in mind this is not a one and done project you will continuly have to monitor and adjust soil conditions.

    Took this from a website:

    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.

    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.

    I hope this helps. Let us know what you decide to do and how successful it is.
  5. Smallaxe

    Smallaxe LawnSite Fanatic
    Messages: 10,082

    Thanks for the responses. :)

    I did miss my opportunity to wizz on them, perhaps a topdressing will do!?!?

    They are planted on the corner of road and driveway, but will be mulched and bordered by stone, so will have to wait and see how the salt trucks and plows treat the area.

    So Plant Buyer83, Your post indicated that P would help decrease the amount of aluminum available to the plant. [Worth looking into, thanks.] Perhaps a cup of bonemeal into each hole in which a pink flower is desired, along with chelated dolomite lime? Would you mix it in at the beginning, or topdress next spring?

    K is then the nutrient that provides the building blocks of a good blue color? or does it also affect the uptake of aluminum and ph? I have cu.yds. of wood ash available, so mixing a little of that in te hole may be useful for K. Though there are claims that the ph of wood ash is alkaline. [Interestting questions for a little study :) ]

    P = pink, while, K and Alum = Blue. Good to know.

    Think I am going to pick up a couple for myself and put them in containers. One for the best possible pink blossoms and one for the greatest blue.
  6. BostonBull

    BostonBull LawnSite Senior Member
    Messages: 520

    Sorry to Hi-jack........

    When is the optimal time to transplant a 1 year old Hydrangea?

    How well will a Hydrangea do in mostly shade.......2-4 hours sun a day max, less later in the year.
  7. Smallaxe

    Smallaxe LawnSite Fanatic
    Messages: 10,082

    We have just moved into prime t-plant time here in Wisco. We have hydrangeas doing well in some pretty dense shade. Like 0 hours of direct sun, for the 'Annabelle', These blue and pink are new to the area, so can't say much about them yet. They have a different leaf and don't get very big.
  8. cudaclan

    cudaclan LawnSite Member
    from Zone 5
    Messages: 152

    4 - 6 hours minimum sunlight for most. Planting time is now.
  9. Plant Buyer 83

    Plant Buyer 83 LawnSite Member
    Messages: 176

    The more north you go the more sun they need. Further south they prefer filtered sun in the afternoon. Perfect time to plant!

    Smallaxe - good question Not sure I know the correct answer - You may not even get the desired color the first year or even 2 - soils can be funny - so many outside factors. I would incorporate some into the soil when planting, then I would almost say wait until they start to bloom then evaluate and top dress accordingly - although at that point it might be too late. I do think a soil sample is key to a good start.

    I would be interested in how this goes for you and what results you find and what worked and what didn't work. Do keep us posted.
  10. Smallaxe

    Smallaxe LawnSite Fanatic
    Messages: 10,082

    Thanks, cudaclan,

    Would you preppare the planting hole for ph?

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