Seven species of spruce (Picea) trees grow native throughout the United States, with around 30 species growing around the world. All evergreen spruce trees produce a pyramidal shape, and most species grow up to 200 feet in height. Evergreen spruce trees offer cold hardiness and ease of care in the landscape. The tree also offers a long lifespan of 200-plus years.
Spruce trees require ample room to grow; the tree will quickly outgrow small yards. Dwarf and small size spruce cultivars are available for limited space sites. The tree requires full sunlight for optimum growth.
The spruce tree, a coniferous evergreen, produces four-sided needles with stomatic lines. The needles feel rigid with points. When old needles fall from the tree, they leave small bumps which persist on the stems. Each needle measures less then 1 inch in length. Needle color varies depending on the spruce variety. Many offer bluish-green, mint green or dark green needles.
Spruce trees have thin bark with a scaly appearance. Branches often have a whorled appearance. The wood tends to be white in appearance with elastic qualities. As the tree ages, the bark tends to have a knotty appearance as branches break. The tree also produces a resin that is used for its turpentine like qualities.
The tree is monoecious, meaning it bears both female and male flowers during the spring months. Cones hang from the tree's limbs and appear mostly on the top branches. Most cones measure approximately 7 inches long depending on the variety. Each cone contains 300 to 350 seeds. In the spring, the cones drop their seeds.
Spruce trees prefer acidic soil with a pH range of 5.5 to 7.0. If the soil pH tops 8.0, the tree grows slowly and is severely stunted for its age. Spruce trees do not do well in clay soil due to the compact soil tendencies which makes it difficult for the tree's root system to spread out. The spruce tree grows 3 to 4 inches per year, but in an area with ample irrigation and good soil, the tree can attain 12 inches per year.