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Color My World with hydrangeas' flower pigments

© Emily Levitt

Nothing fills in the summer garden like a fully mature hydrangea. The range of color present on one bushy plant alone can present a multitude of different hues.

This occurs due to the pH sensitivity of hydrangeas' flower pigments (anthocyanins). When grown in alkaline soils, pink or purplish are produced, while those plants grown in acidic soils produce blue flowers.

Pink colors occur at pH levels between 6.5 and 7.5. Many reference sources decry high acid soils as too tough for hydrangeas to tolerate. I guess the authors of these articles haven't driven through north Georgia, because hydrangeas here seem happy with their feet full of red clay.

The blue lace-cap blossom, shown at left, is typical of the native Japanese variety first bought to Europe in the nineteenth century. This color is also common in the highly alkaline soil present through much of the deep South.

The jagged edges on the leaves are indicative of it's specie as well; serrated leaves appear on 'macrophylla' cultivars.

A good, basic listing of the genus, specie and subspecies can be found at The Genus Hydrangea taxonomic page. This listing was first published in 1957. There have been numerous introductions since then, but even the specie descriptions will remain true to the forms described here. There are more than five hundred known cultivars.

A comprehensive list of specie plants and their uses in gardens and landscapes may also be found at Botany.Com.

The use of 'hydra' in its' name tells a lot about its' growing preference. Hydrangeas require regular watering, as they are shallow rooted. Here in the south, afternoon shade is also a preferred growing habit. Plants in direct sun wilt in the high heat of the day, but will recover their upright habit in the cool of the evening, if they have enough water available. Soaker hoses buried a few inches under the soil provide an ideal way to keep hydrangeas happy even, in the current drought. Watering from above can break off the heavy blooms, especially on mophead varieties, as they fill with water and droop.

Imagine what would happen to this pink 'French' (macrophylla) bloom in a downpour, and you'll get the idea! The cultivar shown here is 'Pia'. Water drawn up from below works best.This techinique also helps the plant establish a mature root system.

The folks at Wilkerson Mill Gardens have written a very good article featuring hydrangeas and their uses in the Southeast. This link comes from the Atlanta Garden Connection, but if you'd like to see more of Wilkerson Mill, (which I keep in my link list on the front page), by all means---have a look! This photograph of the lace-cap serrata cultivar "Preziosa" comes from their site. You must write for their catalog to order from them. The catalog is full of good reference material, but the site is worth viewing in any case.

The copyright of the article Color My World with hydrangeas' flower pigments in Gardening in Southern U.S. is owned by Emily Levitt. Permission to republish Color My World with hydrangeas' flower pigments in print or online must be granted by the author in writing.