Puya alpestris aka Sapphire Tower

Puya alpestris is an evergreen perennial in the bromeliad family. It comes from central and south-central Chile. Gardeners also call it mountain puya or turquoise puya. Chicago Botanic Garden describes its home as dry mountain land. There, morning dew supplies much of the water it needs. The RHS describes it as a ground-growing bromeliad.

The plant forms a clump of narrow, dark green leaves. Each leaf arches outward and bears spines along its edges. These spines help deter animals that might eat the leaves. The leafy clump stands about 2 feet [0.6 metres] tall. The RHS gives a mature height of 3.3–4.9 feet [1–1.5 metres]. Its spread reaches 1.6–3.3 feet [0.5–1 metre]. Plants take five to ten years to reach full size.

Tall flower spikes rise above the leaves in dense clusters. The blooms range from metallic turquoise to near black. Orange anthers stand out against the dark or blue flowers. The RHS places flowering in summer. Chicago Botanic Garden lists bloom from January through April. Thus, the reported flowering season differs between these sources. Plants raised from seed can take years to flower. Chicago also lists the plant as attracting birds and butterflies.

Give this plant full sun and soil that drains well. The RHS lists both sandy and loamy soils as suitable. It accepts acid, neutral, and alkaline soil. Outdoors, choose a warm spot with shelter from harsh weather. Protect the roots from wet soil through winter. Under glass, use compost made for ground-growing bromeliads. Water moderately during active growth, from mid-spring through late summer. The plant also withstands drought. The RHS rates it H3 for mild parts of Britain. Chicago lists USDA hardiness zones 8–12.

Its bold form suits gravel gardens and sheltered courtyard beds. The RHS also suggests wall-side borders and Mediterranean-style planting. Chicago lists it for borders and as a specimen plant. It needs no pruning, but scale insects may attack it. Wet soil can cause root rot. Feed glasshouse plants with low-nitrogen fertiliser every six to eight weeks during growth. Sow ripe seed at 19–24°C to raise new plants. Neither source provides guidance on eating the plant or its toxicity.