Hydrangea (Hortensia) is not generally considered a water-saver. However in the cloud forest along the So Cal coast, hydrangeas---hydrangea macrophylla---in old gardens (along with Belle of Portugal roses) have survived for 50 years or better, planted as foundation plantings with an eastern (morning sun) exposure without extra water. In this garden 6 hydrangeas grown from cuttings from an old garden in the neighborhood, survive handily, bloom copiously, and manage on a soaker hose every 3 weeks to keep them blooming in summer. Hortensia survive with rainwater once the roots are well-established (thanks to the cloud cover), losing only leaves if drought stricken. The plants survive.
Our mop heads came to the Americas via the Azores but originate in Asia. There about 110 different kinds--- mopheads and lace caps being the most familiar around here.
The small potted plants from the grocery store will grow along the coast. A lot of websites airily aver you can turn your pink hydrangea to blue or purple by adding aluminum sulphate to the soil. This will work on the East Coast (or anywhere the soil is naturally acid.) It won't work around here if you plant your hydrangea in the ground, because our alkaline soil prevents the aluminum sulphate from working.
If you must have blue--and it is lovely--put the plant in a pot of acid soil, then add the aluminum sulphate in the fall. However, you no longer have a drought resistant plant--- you have to water all the time---to be green, better to enjoy your hydrangeas pink.
Astromeria aurea Golden Lily of the Incas
Astromeria, also called Peruvian Lily is another tough plant, drought resistant, blooming naturally after the winter rains, blooming much longer with an occasional soaking. Why Peruvian when actually our plants are hybrids of a plant from the mountains of Chile and another from the highlands of Brazil ? To Europeans of the 18th c. all of Spanish S. America was called "Peru".
Though looking somewhat like a lily, it isn't. It's a rhizomous plant with water storing tubers, not unlike a dahlia. Our hybrids, developed mostly in England and Holland, are a cross between the winter blooming plant from Chile and the summer blooming plant from Brazil. It now comes in about 10 colors and new colors are being hybridized. It's a long lasting cut flower--one of the best.
Atromeria bloom spring through summer. The trick to keep the flowers coming is to pull the flower off, not cut it. It then hastens to produce another flower stalk.
The seeds of astromeria were brought back to Linneus by a student of his, Claus von Astroemer who went on one of the earliest voyages of botanizing in S. America in 1753.* Linneus, no slouch at "branding" named the pretty Golden Lily of the Incas for the very wealthy father of Claus Astroemer. ("Keep those cards and letters coming...")
Linneus dressed as a Laplander
* Claus actually described the Humboldt current 50 years before Humboldt. He was quite an adventurous fellow though you might not think so to look at him. Became a Baron, started a botanical garden at Gotheburg and has a perfect right to look pleased with himself.
Claus von Astroemer