Parry's Agave
Agave parryi
USDA Hardiness Zones: 5-10
Height: 2-3'
Spread: 2-3'
Sun Exposure: Full sun
Flower: Yellow but rarely blooms
Description: Reliably winter hardy to USDA Zones 7-10. Best growth occurs in a sandy/gritty, dry to medium moisture, well-drained soil in full sun. Tolerates some light shade. Sharp soil drainage is important. Poorly-drained soils inevitably lead to root rot. Tolerates dry soils and drought, so great for water wise, xeric plantings. Surprisingly good winter hardiness for this succulent. Plants have reportedly survived winters with temperatures as low as -20F (USDA Zone 5), but cold temperatures should be "dry cold" as opposed to "wet cold".
It is most noted for its attractive blue-gray to gray-green evergreen leaves, but is also noted for its infrequent but spectacular flowering spikes. Thick, rigid, smooth, ovate to oblong, blue-gray leaves (to 12" long) form a large, dense, symmetrical, basal rosette. A rosette will typically mature over time to 2' tall by 3' wide. Each leaf has spiny margins with a one inch terminal spine. Suckers/offsets root at the base of the rosette forming over time a colony of rosettes. Each rosette will flower only once, usually at some point between 10-15 years (not the 100 years suggested by the also-used common name of century plant used for some agaves), but sometimes flowering will not occur until 20-30 years. One huge flowering stalk (to 20' tall) will rise from each rosette, with each stalk producing 20 to 30 side branches and with each side branch containing a large cluster of creamy yellow flowers.