This Week’s Featured Plants

A wild violet from the Mediterranean with large, one-inch, bright purple flowers produced over a long season. Heat tolerant and perennial, it combines well with other colors in the garden and can take considerable drought. Excellent in morning sun/afternoon shade and in the rock garden. Reseeds moderately. 6″ – 8″ tall and wide. Blooms early spring to late fall. Moderate to low water requirements. (image above from Plant Select).

Callirhoe involucrata – Prairie Winecups

This long-lived native develops a thick, deep taproot and thrives at the front of the border, in the wild garden and xeriscape.  It enjoys full sun, blooming with wine-red flowers from April to hard frost. Perennial, water-wise and does well in heavy clay soil. Tips from the pros: less water and some pinching back will help this plant stay more compact and not spread so wide. It does self-seed so remove any seedlings when they are young, before the roots get a good foothold.  6-8″ tall by up to 30″ wide. Drought tolerant deciduous groundcover, attracts native pollinators. Free of diseases and pests, except for rabbits, who love to eat it.

Tanacetum niveum – Silver Tansy

A near-perfect perennial plant for Colorado, Silver Tansy is drought-tolerant, deer-proof, covered with flowers suitable for cutting, highly aromatic, attracts butterflies, and provides silver foliage and small daisy-like flowers. Tansy takes full sun, and grows 2′ by 2′.

Rosemary has been assigned a new botanical name: Salvia rosmarinus.

‘Arp’ rosemary is an upright cultivar noted for displaying excellent winter hardiness (may survive zone 6 winters with protection – so sometimes hardy here).  It can grow 2-4’ tall and as wide with light blue flowers. The aromatic, gray-green foliage is can be used for seasoning Mediterranean dishes. Be sure to grow it in the warmest, sunniest spot in your garden (in front of a south-facing foundation or large rock is perfect). We know of plants that have thrived in Boulder gardens for as many as 9 years. For the first two winters, we recommend a 4”-thick winter mulch of half compost, half coarse builder’s sand over the root zone.