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garyz8bpnw

Flower color in Hydrangea. Any one yet see a true orange or yellow?

garyz8bpnw
6 years ago

Of the Hydrangea flower color possibilities. In prime condition flowers I've only seen red/pink to purple to indigo/blue, green and white and mixtures between them.

I've seen hints of yellow and orange (without spray paint) only in past prime flowers. And the these may be due to light green shading masking as yellow.

White colored hydrangea flowers have little or no pigment. Greens can be present too and change over time too. The most likely explanation for green is chlorophyll content rather than other pigments. This makes sense since flower petals are actually modified leaves. Starting as green buds chlorophyll production potential is already present.

The predominant color explanation in Hydrangea flower color is that color density is set by the amount of a red colored flavanoid pigment within the petal tissue. Thus light pink to dark red colors are be formed due to pigment concentrations present. Other colors such as white and green can also be present as explained above.

This flavanoid also binds Aluminium ions when present within the plant tissue to form a deep blue colored pigment. This complex gives flowers a light blue to dark blue flower color again depending on the amount of pigment present.

Aluminum is often quite abundant in soil but being a multiple Al+++ positively charged ion it is tightly bound to the negatively charged soil matrix. When present in soil acids yield Hydrogen H+ ions that compete with the bound Aluminum ions and free them for uptake by the plant.

The flavanoid uptake and/or binding of metal ions is weak so there has to be elevated free aluminium ions present in the soil to elevate ion uptake and drive the resulting flower color fully to blue. Stop midway with the Aluminum only partially saturating the initial red pignent present and you have a mixture of red and blue pigments yielding light to dark purple flower color.

Aluminum Sulfate addition is a neat trick because it adds abundant free Aluminium. If Aluminum ions exchange with H+ and binds to soil it makes sulphuric acid which acidifies and helps to free Aluminum ions again.

Here's an example of color range on one hydrangea variety with acidifying soil pH (most acidic top to most basic bottom). At the most acidic pHs pigment production is inhibited and floret size stunted. Thus, hydrangea are only able to show such a wide color range because they grow over a wide pH range!

Example soil pH effect on hydrangea color.

The above explanations cover the dominant color mechanism for flowers in prime condition.

In past prime flowers multi color effects can be caused by variations in tissue pH within the petal tissues. These florets all started light pink.

Much like tree leaves hydrangea flowers going past prime often form other colors and later go brown.

The yellowish effects on hydrangea flowers seem to be from light greens rather than true yellow pigments.

In fall tree leaf color result from chemical flavanoid pigment conversion into other forms, breakdown, as well as new production of different flavanoids and other pigments. This range plant possibilities might thus exist for hydrangea colors IF the red-purple-blue explanation finds exception.

Past prime Hydrangea macrophylla 'New Wine' flower color teasing with an orange like hue (red with light green).

It would be a true breaththrough in Hydrangea color range if a plant with true yellow pigment can be found or created. The whole sunset color range might then be possible adding the missing yellow to orange range in the already broad color palate.

Theorically this is possible from mutation or foreign gene introduction via sucking insect foraging, ballistic gene introduction (sand storm or gene coated pellets shotgun fired into a plant, or direct lab transfer of specific genes.

Anyone growing hydrangea near yellow roses or other flowers? Keep your eyes open!!! Be sure to take and grow a stem cutting IF you ever see a yellow or orange hydrangea flower.

Many of our most interesting new plants have come from discovering a new different genetic variety within a field of initially similar plants. New strains happen all the time but at a low rate of probability. They are lost if not discovered and propigated.

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