Picea pungens ‘St. Mary’s Broom’ (syn. ‘St. Mary’) – This Colorado Blue Spruce cultivar was discovered as a ‘witches broom’ in New Jersey. It is a good choice for rock gardens and holds its silvery-blue colour quite well. ‘St. Mary’s Broom’ is a long-lived conifer that requires no pruning. Best in full sun with good soil drainage. Grows 24-30″ high by 4′ wide. Hardy to zone 3.
Picea abies ‘Little Gem’ – This RHS Award of Garden Merit winner is a sport of Picea abies ‘Nidiformis’ (Bird’s Nest Spruce) and forms a domed or cushion-shaped shrub off the ground. It is quite slow growing (up to 3″ a year) and the new growth is a brilliant lime green, contrasting well with the darker foliage below. Grows 18-24″ high by 2 to 3′ wide. Hardy to zone 3.
Picea pungens ‘Glauca Globosa’ (syn. ‘Globosa’) – A dwarf globe-shaped Colorado Blue Spruce with 1.5″ long sharp silvery-blue needles that are brighter as they emerge. It is an RHS Award of Garden Merit winner and more coarsely textured than ‘St. Mary’s Broom’. This common cultivar and is often trained as a top-grafted standard. Grows 3-4′ high by 4-6′ wide. Zone 2.
Picea glauca ‘Rainbow’s End’ – This cultivar has the expected symmetrical cone-shaped growth habit of the Alberta Spruce but with new growth tips that are butter yellow and really stand out at a distance. It was discovered in 1978 as a sport at Iseli Nursery in Oregon and is quite slow growing. Works well in containers.Grows 6-10′ high by 4-6′ wide. Hardy to zone 3.
Picea glauca ‘Sander’s Blue’ – The new growth of this cone-shaped conifer is a distinct silvery-blue, maturing to a greyish-green. It is a sport of Alberta Spruce (Picea glauca ‘Conica’) and as with most of these is prone to mite damage. You can avoid this by blasting out the old interior needles with a hard spray of water from your hose. Grows 6-10′ high by 4-6′ wide. Hardy to zone 3.