Editing Hydrangea (section)

==Colors and soil acidity==
[[File:Hydrangea Flower Color Based on Soil pH.jpg|thumb|Hydrangea flower color changes based on the pH in soil. As the graph depicts, soil with a pH of 5.5 or lower will produce blue flowers, a pH of 6.5 or higher will produce pink hydrangeas, and soil in between 5.5 and 6.5 will have purple hydrangeas.]] 
Hydrangea flower color can change based on the pH in soil. As the graph depicts, soil with a pH of 5.5 or lower will produce blue flowers, a pH of 6.5 or higher will produce pink hydrangeas, and soil in between 5.5 and 6.5 will have purple hydrangeas. White hydrangeas cannot be color-manipulated by soil pH because they do not produce pigment for color. In other words, while the hue of the inflorescence is variable dependent upon cultural factors, the color saturation is genetically predetermined.  In most species, the flowers are [[white]]. In some, however, (notably ''H. macrophylla''), they can be blue, red, or purple, with color saturation levels ranging from the palest of pinks, lavenders & powder blues, to deep, rich purples, reds, and royal blues. In these species, [[floral color change]] occurs due to the availability of [[aluminium]] [[ion]]s, a variable which itself depends upon the [[soil pH]].<ref>{{cite web |url=http://www.caes.uga.edu/Publications/pubDetail.cfm?pk_id=7829 |title=Publications - UGA Cooperative Extension |website=www.caes.uga.edu |access-date=31 May 2018}}</ref><ref>{{cite web |url=http://www.usna.usda.gov/Gardens/faqs/hydrangeafaq2.html |title=USDA: Hydrangea Questions and Answers |access-date=31 May 2018 |archive-url=https://web.archive.org/web/20130516083220/http://www.usna.usda.gov/Gardens/faqs/hydrangeafaq2.html |archive-date=16 May 2013 |url-status=dead}}</ref> For ''H. macrophylla'' and ''H. serrata'' cultivars, the flower color can be determined by the relative acidity of the soil: an acidic soil (pH below 7), will have available aluminium ions and typically produce flowers that are blue to purple,<ref>{{Cite EB1911|wstitle=Hydrangea |volume=14 |page=34; see line five |quote=...but by the influence of sundry agents in the soil, such as alum or iron, they become changed to blue}}.</ref> whereas an alkaline soil (pH above 7) will tie up aluminium ions and result in pink or red flowers. This is caused by a color change of the [[flower pigment]]s in the presence of aluminium ions which can be taken up into [[Phytoremediation, Hyperaccumulators|hyperaccumulating plant]]s.<ref>{{cite web |title=Hydrangea Plants |url=http://www.whiteflowerfarm.com/hydrangea-shrubs-spring.html}}</ref>