Black Hills Spruce or Picea glauca is a large evergreen tree that is slow growing and smaller compared to white spruce varieties. With its dense, hardy needles, Black Hills spruce can help to prevent soil erosion and add shade to your landscaping.
Black Hills Spruce
As an evergreen, the Black Hills Spruce has needles that grow from lateral branches and form a broad pyramid and conical crown. The needles are attached individually, and the foliage color can vary from deep green to a blue green. Mature Black Hills spruces can grow to up to 5 feet, with a spread of up to 25 feet. However, this spruce has a slow growth rate compared to other spruce species to produce a height increase of less than a foot per year.
Black Hills Spruce are considered resistant to diseases and pests, and require minimal care throughout the year. You may need to prune to remove dead branches and encourage bushier growth, but once established, your Black Hills spruce is unlikely to need much maintenance and can last up to 300 years.
The Trunk and Branches
The Black Hills Spruce have a central trunk with ascending, lateral branches. The bark is thin and an ashy gray, brown color. The bark is fissured shallowly, and it separates into flaky, thin scales. This provides an ideal structure to create a broad pyramidal foliage of needles with brown cones appearing from late July.
Foliage
Black Hills spruce trees have individually attached needles to create a foliage that varies from dark green to a blue green color. This can add vibrancy to any garden, while protecting your outdoor space from soil erosion.
Uses in Your Garden
Black Hills Spruce can make a fantastic feature in a lawn or to anchor foundation planting. The pyramidal, uniform shape provides formal character in any type of garden design. You can use Black Hills spruce in mixed planting, adding taller trees in the background to create a superb feature. This type of spruce is an ideal partner plant to add color, style, and fragrance to your landscaping.
You can make a pathway by staggering the rows of Black Hills spruce to create a cool retreat for summer shade. Black Hills spruce can be used to create a perimeter around your property, to create a boundary, wind break, or simply ensure that you don’t suffer soil erosion problems.
Cultivation
Black Hills spruce are quite low maintenance, thriving in most types of soil, with tolerance for colder conditions.
Light
Black Hills spruce trees can tolerate full sun through to partial shade, but optimal conditions are full sun, with a minimum of four hours, unfiltered, direct sunlight every day. However, since the Black Hills spruce has a shallow root system, if you plant in a position of full sun, you will need to check for soil moisture levels periodically. The root system can be vulnerable to drying out, so you should water when the soil becomes dry.
Soil
Black Hills spruce has widely adaptable soil condition requirements. It can grow well in moist, acidic, gravelly soil and even fine clay or sandy loam type soils.
Water
Depending on the rainfall in your area, new spruces need to be watered through the first growing season every week. A one hour, slow trickle of water is usually sufficient, but during hotter spells, you should soak the ground every few days rather than watering daily. This type of deep watering will encourage root growth for a sturdier plant that has greater drought tolerance.
You should monitor your new Black Hills spruce trees during the first two years after planting to ensure that they have sufficient moisture. After this point, the trees should be resilient enough to survive on their own with decent drought tolerance.
Winter Hardiness
Established Black Hills spruce have excellent winter hardiness, tolerant in a temperature range between 50ºf and -40ºf. This extreme cold hardiness makes this tree ideal for geographical areas prone to significant temperature variance. Additionally, unlike many other winter hardy trees and shrubs, deer do not like the taste of this spruce, so you won’t find your tree compromised by hungry visitors to your garden during winter. Black Hills spruce is also resistant to winter injury and can perform well regardless of any harsh winter conditions.
Heat Resistance
According to its American Horticultural Society Heat Resistance rating, Black Hills Spruce is rated for zones 2 to 8. This is based on the number of days above 86ºf on average per year.
Pests and Diseases
Black Hills Spruce have been found to be resistant to diseases and pests, but they are susceptible to some issues including:
Spider Mites: Spider mites are a common pest, compromising the appearance of the plant. They live on the plant, spinning protective silk and causing puncture damage to the plant cells as they feed.
Needle and Stem Rust: This only affects the current year’s needles as mature needles are resistant. It creates orange color spore masses that erupt from the infected needles.
Canker; A canker is a dead section of bark on the main trunk or branches of the tree. The bark can be killed by plant pathogens or mechanical injuries.
Trunk and Root Rot: This is the result of a fungal infection causing yellowing and stunted growth.
Lirula Needle Blight: This can cause graying of the needles and in some cases of infection, black bands across the affected needles.
Fortunately, most of these issues can be combatted with preventative measures and the proper care.
Fertilizing
Established Black Hills Spruce trees require fertilizing every couple of years. You should feed in early spring as the growth season begins. This can be accomplished with liquid feed, slow release or granulated fertilizer products. You should choose a product that is designed specifically for trees and offers a general purpose, nutritionally balanced composition. You should avoid over fertilizing as it can result in plant injury.
Pruning and Trimming
Pruning can be necessary to remove any dead branches and encourage growth. You should remove any dead branches close to the trunk as flush with the bark as possible. To control the shape and size of your spruce, cut just above the leaf buds, at a slight angle to encourage new growth sprouts.
You should always use clean, sharp tools for pruning and tree saws are best for mature, large trees. If your spruce has grown beyond where it can be safely pruned, it is a good idea to call a professional tree service.
The Origins of Black Hills Spruce
The white spruce family is a hardy evergreen that is native to the United States. It is found across the boreal region from Alaska and Canada dipping down into Minnesota and New England. Black Hills is a white spruce variety that is native to the Black Hills of South Dakota. In the Black Hills, the tree grows slowly, but it has a denser, brighter foliage with shorter cones compared to other white spruce varieties.
Black Hills is considered to be a superior ornamental tree, and it is also the South Dakota state tree.