How to Plant, Grow, and Care for Blue Spruce Trees

Native conifers are essential additions to the garden. They provide year-round ornamental interest with needles, cones, and scaly gray bark. The branches provide habitat space for birds, squirrels, and small mammals. The cones feed hungry birds and squirrels, while the flowers offer valuable resin for nest-building bees.

Not only are blue spruces valuable for wildlife, but they’re also easy trees to care for. They perform well in their native range without additional care. They’ll need some maintenance if you grow them outside their preferred habitat, although they’ll grow more drought-tolerant and frost-hardy as they mature. 

Blue spruce, or Colorado spruce, is perfect for native plant gardens, living fences, or specimen plantings. It’ll slowly extend over 50 feet tall with a wide base, filling bare sites with lovely evergreen foliage. Rather than traditional conifer green, go for the bright gray-blue of the blue spruce tree! 

What Is It?

Blue spruce is an evergreen conifer, meaning it keeps its bright blue needles on its stems throughout the year. It starts as a young sapling and slowly matures into a large, towering tree. 

Native Area

Blue spruces originate in mountainous regions from Montana to Mexico. They grow water-preserving needles at high altitudes to conserve moisture when it’s scarce. You’ll find them growing wild in Wyoming, Colorado, and Montana. They’re the official state tree of Colorado! 

Although blue spruce is a western conifer, it thrives in cool sites from USDA hardiness zones 2 through 7. I see these evergreen trees growing in yards throughout my region of the Pacific Northwest in zone 8. So long as you provide consistent moisture and avoid excessive summer heat, you can cultivate blue spruce in your garden. 

Characteristics

Spruces, or trees in the genus Picea, share some of the same traits. These conifers grow spiny, evergreen needles that attach to the stems on pegs known as sterigmata. The pegs persist on the stems long after the needles fall off, and you can use them to help you identify this tree from firs or pines.

Blue spruces have characteristic blue-green needles. They emerge bright blue at first and fade to a dull green. In the nursery trade, species used for propagating and selling are bright blue specimens under the name Picea pungens var. glauca. These retain their blue color better than most wild trees do. 

Spruces sprout decorative cones that mature throughout the year. Blue spruces sprout bright red-purple cones that mature to a light brown. The cones hang onto the tree while they release seeds below when conditions are favorable for germination. Some large cones reach up to ten inches long!

Because spruces are wild trees, they grow to epic proportions in their native range. You can expect blue spruce to reach between 30 and 60 feet tall when it’s mature. It’ll hold onto the lower branches, creating a pyramidal structure reminiscent of Christmas tree shapes.  

Planting

You’ll find these trees available as potted saplings in nurseries throughout North America. Although sold in eastern states, they perform best in regions near their native range, or cold climates from zones 2 through 7. Consider choosing a different spruce that’s local to your area if you garden in warm regions of the Southeast.

Growing from Seed

Spruce seeds take some time to grow. They don’t require cold winter temperatures before they sprout roots and shoots, but cold stratifying them will promote better germination. Sow seeds during the fall and let them stratify outdoors, or keep them in your fridge for two months before sowing them in spring. 

Before sowing seeds in the fall, soak them for a day. Do the same for seeds you intend to sow in the spring, but instead, soak the seeds after removing them from the fridge in spring. Plant them after soaking; choose whether to grow them in the ground or in containers. 

Cover the seeds with a thin layer of mulch or compost if you’re planting them outdoors, and bury them a half-inch deep if you’re growing them in pots. The seeds will sprout as temperatures warm in spring and summer. Have patience, as the seedlings may take weeks or months to germinate. Keep the seedbed free of weeds and unwanted debris, and ensure the soil stays moist. 

Transplanting

Whether you’re transplanting mature, potted specimens or young saplings, preparation is key to successful transplanting. Create the right environment for your blue spruce tree and it’ll adapt readily to the new home. 

Start by first digging a hole. Dig a hole as deep and twice as wide as the tree’s rootball. Avoid adding amendments to the soil, and set it aside for burying the roots. 

After you dig the hole, remove the tree from its container and inspect the roots. You’ll want to release bound or circling roots and arrange them downwards. It’s okay to cut some of them off before transplanting, as this stimulates new growth from the wounds. Cut any woody roots that grow upwards or in circles. 

With some root treatment, your tree is ready to enter its new home. Set it in the hole so the trunk’s base sits at the soil’s surface. Add the dug soil back to the hole until it’s full, then water well. If water condenses the ground so it falls below the surface, add some more soil to compensate. Now is the time to add mulch or compost on top, as they help your tree adapt and thrive.

How to Grow

Blue spruce trees require moist, cool conditions to thrive, although they’re drought-tolerant after they establish themselves. Give them what they need and they’ll reward you with evergreen needles, beautiful cones, and scaly bark. 

Light

Blue spruces prefer full sun and will tolerate partial shade. They grow best in open sites where they receive between six and eight hours of direct sunlight daily. Avoid growing them in shady sites or underneath other larger trees, as their crown eventually reaches epic proportions. 

Water

These evergreen conifers need consistent moisture during the growing season while they’re young. New transplants also need extra water while they adapt to their new environment. Avoid letting young saplings dry out, and ensure the ground stays moist throughout the seasons. 

Once blue spruces establish themselves, they tolerate short stints of summer droughts. Cut back on watering for mature trees, and avoid watering them at all if you’re growing them within their native range.

Soil

Spruces prefer well-drained soil that’s rich in organic matter. Provide a mix that has ample drainage, fertility, and porosity. Amendments like perlite or vermiculite allow air and water to stay under the soil where roots can access them. 

You can amend poor soils with a thin layer of compost, mulch, or leaf mold. The amendments release nutrients while they decay, and they provide air spaces under the soil for oxygen and water to enter. Whether you grow blue spruce trees in poor or rich soil, adding compost annually boosts their health and performance.

Fertilizing

Blue spruces need little fertilizer when growing outdoors. Consider giving them a regular dose of organic fertilizer in spring and again in early summer. This will ensure the needles retain their blue hue as they mature so you can enjoy their wonderful color. 

Small potted cultivars may need more nutrients than those growing in the ground. Add organic fertilizer to potted specimens once a month during the growing seasons. 

Maintenance

Blue spruce trees need little maintenance. You may prune their lower branches if you prefer an open base. Otherwise, let them grow into their natural shape. Prune dead branches as they appear to keep a neat appearance. 

Propagation

Why stop at one blue spruce? Propagate your tree to have dozens of new seedlings. Blue spruce trees are easy to propagate from cuttings. You may also save their seeds to try your knack for growing new seedlings. 

Cuttings

Cuttings are not the easiest method of propagation, but it’s possible to grow several new trees with them, especially if you’re growing a container tree. Softwood cuttings perform well in midsummer. Cut four to six-inch portions off the stems, and remove their lower leaves. Put them in containers with moist potting soil. Then, place them under dappled sunlight or partial shade while they root.

Softwood cuttings form roots within a few months before entering winter dormancy. Grant them shelter in the winter in a cold frame, hoop house, or unheated greenhouse. They’ll be ready for transplanting by spring. 

Hardwood cuttings are another option. Take cuttings from late fall through mid-winter off dormant blue spruce trees. Place them in pots with a free-draining potting mix, and give them similar shelter as softwood cuttings using a cold frame or similar structure. Keep their soil moist from winter through fall, then transplant them the following autumn before they enter dormancy. 

Seed Saving

These conifers sprout seeds with long bracts that poke out of their cones. The seeds fall off the cones when they’re ripe. Collect cones off the ground and you’ll find them empty and bare. The best way to collect seeds is to cut the cones off before they fall.

Find semi-ripe cones that dangle downwards. Prune them off, then place them in a brown paper bag to dry. The seeds will pop out of the cone and fall to the bottom of the bag when they’re ripe. Collect them into a glass, plastic, or paper container and store them in a cool, dark location.

Popular Varieties

The species tree Picea pungens is a lovely addition to any native plant garden. Curious growers should try a cultivar with unique attributes. Start with one of these four, or explore your options at a local nursery. New varieties offer dwarf forms, mesmerizing foliage, or weeping tendencies. 

‘Glauca Pendula’

If you’d prefer a shrubby ground cover instead of a tree, ‘Glauca Pendula’ is the right choice. It grows low, spreading many feet horizontally in each direction. Give it a trellis to grow up and over, or let it ramble on the ground as it pleases. 

‘Glauca Globosa’

This globe-shaped variety looks more like a shrub than a tree. ‘Glauca Globosa’ sprouts low to the ground without many branches. It forms a round, dome shape that matures to five feet tall and six feet wide. Some nurseries offer this variety on a standard trunk, making the appearance of a blue spruce lollipop! Plug this cultivar in amongst other low-growing green shrubs for lovely blends of color. 

‘Montgomery’

This dwarf spruce looks much like ‘Glauca Globosa’ when it’s young, with a round ball shape. As it matures, it grows into a Christmas tree shape with short, squat branches. This variety is perfect for small gardens, as it stays under eight feet tall in maturity. 

‘Baby Blue Eyes’

‘Baby Blue Eyes’ is larger than dwarf varieties but smaller than the species type. It reaches up to 30 feet tall, although the base stays narrow and thin. Dense branches remain on the tree all along the trunk, creating an eye-catching spectacle. Grow it with other thin, tall conifers like ‘Pendula’ Nootka cypress. 

Common Problems

These native evergreen conifers face relatively few issues in their native range. Some insects target the trees, while diseases may infect them when they grow outside their preferred habitat.

Pests

Mistletoe, the holiday decoration, is a pest of spruce trees! It is a parasitic organism that grows on woody branches, infecting the stems with its roots that suck nutrients and water from the tree. Mistletoe rarely kills a spruce tree, although it can weaken it so that it falls in storms or extreme droughts. Remove the mistletoe to avoid further infections, then wait for it to reappear before chopping it off.

Spruce budworms infect trees both in and out of their native range. Moths lay eggs that hatch into needle-feeding larvae that quickly defoliate entire branches. They can kill trees in urban settings, although healthy specimens in backyards and wild spaces often defeat the infestation. Apply organic fertilizer or compost to your tree’s soil to boost its pest resistance. 

Spider mites are a common pest in warm, dry regions. They set up their homes on the leaves, weaving intricate, tiny webs to crawl from stem to stem. Wash them away daily with strong streams of water. They should disappear after a week or two of spraying.

Bagworms may also feed on your trees. Just as with budworms, they won’t eliminate a tree in a wild setting, or in a large stand. However, you can remove them if needed.

Diseases

Root rot and canker are two common spruce infections. Discourage both by moderating the soil moisture so it’s moist and not soggy. Chances are your tree is already dying if symptoms of root rot appear. Start by watering less and pruning off any dead or dying branches. Only water the site again once the ground dries on the surface. Your tree may recover if you correct the moisture levels quickly after spotting a problem. 

Canker is another blue spruce infection. It rarely kills, although it may weaken the tree so other insects or pathogens can move in. If the canker appears on the trunk near the roots, leave it be. If it’s on the tip of a branch or stem, cut it off and moderate the soil so it stays moist, but not soggy. Heavily affected trees should be removed to prevent spread to other nearby plants.