Colorado Spruce Koster A beautiful tree with prickly, silvery-blue needles, Picea pungens Koster is a compact, rather slow-growing, small to medium-sized, evergreen tree; it has a tidy, conical habit. This tree makes a great accent plant in the landscape, and is particularly good in an architectural or low maintenance garden. An easy tree, it needs no pruning, is disease-free, but may be attacked by aphids and conifer red spider mite. It must have acidic to neutral soil, as it will not tolerate lime. Site: Shelter from cold, drying windsSoil: Moist but well-drained, acid to neutral soil Position: Full sunSeason of interest: All yearHardiness: Extremely hardyHeight:  26-40’ (8-12m) Spread: 8-13’ (2.5-4m) in 20-50 years