What People Say. 1  David Bush and Jim Parsons Authors, Fair Park Deco Fair Park is one of the finest collections of Deco architecture in the country, but it is so much more: the embodiment of Texan swagger, it is a testament to the Texanic task of creating a dazzling spectacle in the darkest days of the Depression..
Hydrangeas turn blue as a reaction to aluminum in the soil. The soil pH should be slightly acidic (5.2 - 5.5). Do a soil test first, to determine your starting pH. Adding aluminum sulfate to the soil will help lower its pH, if necessary. A word of caution: not all plants can tolerate acidic soil and neighboring plants may be adversely affected.
Some salts are very hydrophilic â they dry and preserve materials theyâre placed with â like salt cod or Virginia ham. Epsom salt is already hydrated and does not pull water from nearby materials. When the ions of Epsom salt disassociate, they have a neutral effect on the pH of the soil. Since the blue color of a hydrangea is formed by aluminum made available in acid soil, adding Epsom salt would not make your flowers change color. Alum (aluminum sulfate) is acidifying and would give the effect you want at two tablespoons per plant.