Picea Glauca ‘Conica’ is an adorable little evergreen spruce tree that will brighten up the room as soon as you introduce it to your home. Perfect plant to decorate for the holiday season and place on your work desk or dinner table for that festive atmosphere. And if you provide it with enough care and love throughout the rest of the year, you can enjoy watching it grow and let it become an irreplaceable decor for your home.
I. Appearance and Characteristics
Picea glauca, commonly called white spruce, is an extremely hardy evergreen conifer that is native to upland areas and lake/stream margins stretching from Alaska across the boreal forest of Canada to Newfoundland, dipping south to Montana, Minnesota, Wisconsin, Michigan and New York. This tree typically grows 60-80′ tall (less frequently to 140′ tall) with a cone-shaped crown. It diminishes in size to low, shrubby forms near tree line in northern Canada. Blue-green needles (to 3/4″) on small woody pegs have sharp tips. Needles are pungently aromatic when crushed. Needles have a glaucous (white waxy coating) bloom, hence the specific epithet and common name. Branchlets do not droop. Cylindrical pale brown cones (to 2.5″ long) have flexible scales.
Genus name is reportedly derived from the Latin word pix meaning “pitch” in reference to the sticky resin typically found in spruce bark.
Specific epithet both are in reference to the fact that mature needles of this tree become glaucous (acquire a waxy white bloom) with age.
‘Conica’ is a dense, cone-shaped, semi-dwarf to dwarf shrub form with soft bright green foliage. It matures over a number of years to 10-13′ tall. Growth rate is 2-4″ per year. Needles (to 1/2″ long) are aromatic when crushed. Cones are rarely produced. Sharp pointed tip will broaden with age. ‘Conica’ was discovered by J. G. Jack and Alfred Rehder at Lake Laggan, Alberta, Canada, in 1904. Plants are often trimmed into topiary forms when grown in containers.
II. How to Grow and Care
Sunlight
White spruce ‘Conica’ is shade-tolerant, so it doesn’t need much direct sunlight to grow. From spring through early summer, it’s best to expose the tree to light for a duration of over 6 hours a day, but a lack of light for a short time won’t affect its growth. In summer, when sunlight is harsh, it’s best to shade small trees grown outdoors to protect them from long-term, blazing light. If they are potted indoors, move them to a cool, shaded place.
Temperature and Humidity
White spruce ‘Conica’ performs best in areas with cold winters and cool summers. This plant does best in low-humidity environments. This mini tree requires good air circulation.
Watering
After transplanting white spruce ‘Conica’, water it consecutively 5-7 times, once every 5-7 days. Mix a little rooting powder in the water; this will help the roots grow. During daily care, keep the soil moist but avoid leaving standing water, as this may cause the roots to rot. In general, water once every 10 days. If the leaves soften and droop, increase the watering frequency. The amount of watering can be adjusted depending on the weather conditions.
Soil
White spruce ‘Conica’ grows well in fertile, deep, well-drained, slightly acidic soils. The best soil pH range is 5.1-7.3, making both sandy soil or slightly clay-like soil good choices. As the tree grows slowly and has a long life span, the soil layer should be about 70 cm thick. If barren, the soil can be improved by adding nutrient soil or organic manure.
Fertilizing
Young plants respond well to mixing in a granular fertilizer around the tree’s base once a year. For an organic alternative, try a natural fertilizer like fish emulsion. Mature trees require no feeding.
Planting Instructions
To grow white spruce ‘Conica’ in a yard, purchase seedlings and transplant them in early spring. Get the planting pit ready one week before transplanting; its diameter needs to be about 20 cm longer than that of the root ball and have a depth of about 15 cm deeper. It should be no less than 6 m away from other plants. Add organic fertilizers to the bottom of the planting pit before transplanting and mix them well with the soil.
Place the seedling vertically into the pit, shovel 2/3 of the soil back, and water thoroughly once to make sure the moisture around the plant’s roots is sufficient. Then, fill the pit fully up with soil and water again. Stomp the soil firmly and keep the pit surface level with the ground. If it’s often windy at the planting site, support the young tree with wood sticks or metal poles in case a strong gale threatens to tilt it or knock it down.
Indoor potted white spruce ‘Conica’ can be directly purchased. The tree grows slowly and usually doesn’t require repotting. Repotting is only necessary if the needles turn yellow and fall off the tree, the roots around the pot brim or at the bottom wither and dry up, or the soil in the pot compacts. Move the majority of the original soil to the new pot with the plant, and add small amounts of organic fertilizers and new soil to provide more nutrients for its growth.
Pruning
White spruce ‘Conica’ has lush terminal buds. The tree usually takes on a beautiful triangular shape and does not require pruning in general. When overly pruned, its incisions secrete rosin excessively which affects the tree’s normal growth. It’s best to trim off overly dense, diseased, and dried branches during the plant’s winter dormancy. Prune and beautify the treetop in early spring when buds sprout. About 1/2 of the young branches can be pruned off to create your desired shape. For large, mature trees, it’s a good idea to prune off all the branches on the lower trunk to reduce nutrition consumption.
When growing white spruce ‘Conica’ for Christmas decorations, you need to control height and width. Prune the treetop and lateral branches appropriately short and continue to cut the newly-grown buds short, as well. Repeat this process many times. Seal pruning incisions with wax or duct tape to keep rosin from effusing.
Propagation
Cutting
The two ways to grow dwarf Alberta spruce are from seeds or branch cutting. The quickest way to propagate this plant is by using a 6-inch-long softwood branch cutting taken in late summer or early fall. Softwood branches are long and firm branches but should not be hardened and woody. Here’s more about the cutting method:
- Gather sterilized pruners, potting soil mixed with peat moss and sand, a 3-inch pot, and a brightly lit location for the cutting to grow.
- Strip the needles from the lower two-thirds of the branch. Dip the cut end into the rooting hormone to promote rooting, then plant it deeply into the soil.
- Keep the soil moist until roots form. As a slow-growing plant, root formation can take up to 6 to 8 weeks. You’ll know the plant is rooting when you notice some new plant growth. Once you notice new growth, transplant it into a larger pot or a landscape location.
From Seed
If you have access to a dwarf Alberta spruce tree, harvest seeds mid-fall. Spruce seeds grow in cones. Pick them young before they ripen. Extract the seeds from the cones by allowing the cones to dry out, open, and spill out the seeds. This can take up to two weeks.
Some people like to scar or weaken the outer coating of the seed to promote germination. These seeds also need temperatures to cool and warm up to make the seed believe the winter season (and dormancy) is ending and the growing season is about to begin.
If you are starting your seed indoors, plant the seeds about 1/4-inch deep in a pot with moistened potting soil amended with peat moss and sand, wrapped in a plastic bag in the back of a refrigerator for about three to four months. Gradually warm up the seeds by moving the pot to a cool garage or basement or taking it outside, periodically hardening off over four weeks as spring approaches, and giving the plant at least 6 to 8 hours of light.
Alternatively, you can also leave the newly potted seed outdoors (sheltered in a non-windy area) during the winter months. The seed will enter dormancy and naturally acclimate to the warming temperatures when spring returns.
Pests and Diseases
Common Pests and Plant Diseases
Dwarf Alberta spruce trees are not very tolerant of air pollution and salt spray, and they struggle in areas with high heat and humidity.1 They require very little care but are often the victims of spider mite attacks that can kill the tree.2 A yearly preventative treatment with a pesticide may prevent this. An organic alternative to a synthetic pesticide is weekly treatment with insecticidal soap.
Common Problems
You must live in zone 3 to 8 to grow this tree outdoors; zones 3 to 6 are the most ideal. It doesn’t prosper well in climates that have really hot, humid summers. But, if you live in a cooler area like the northern U.S. or Canada, then this plant is much easier to grow. The biggest problem with a dwarf Alberta spruce is its need for plenty of air circulation to keep pests like pesky spider mites away. Do not crowd this plant to keep it happy.
Needles Turning Brown and Dropping
The dwarf Alberta spruce’s needles will turn brown and drop if it gets crowded. If this happens, trim off the brown leaves. New growth may reemerge. Excessive heat, winter burn from harsh winds or too much sun exposure, and too much water, or not enough water may also cause yellowing and browning.3 Adjust those conditions, if possible.
Crowded conditions will also encourage a spider mite infestation.1 To check for mites, get a piece of white paper and shake the branches over the paper. If you notice insect activity, it is likely a mite infestation, and they can appear as red, green, or black oval specks. Make sure the plant is not crowded, wash away spider mite webs and insects, and start treatment with an insecticidal soap weekly.
Browning Reaching the Trunk
Winter burn can occur during sunny winter days when the needles dry out since the branches and roots have very little access to water.3 The browning will appear lopsided, mainly at the south or west part of the plant—where the sun is usually strongest. To prevent winter burn, water the plant fully in the fall before the ground freezes so the roots can soak up the moisture before the ground freezes. Cover the ground at the tree base with 2 to 4 inches of mulch to reduce moisture loss. If the entire tree turns brown, the plant is a lost cause. Replace it and start again with a regular watering regimen or a different sun exposure.
Browning at the Top of the Plant
If the top of the dwarf Alberta spruce begins turning brown, it is likely a problem with the trunk or the roots. Closely inspect the trunk to see if animals are chewing the base of the plant. If the bark is gone from the plant, the tree will have to be replaced. If the plant is getting too much water, its roots can be rotting or drying out, killing the tree and requiring replacement. If you catch the problem soon enough and the plant is still small, you can dig up the root ball and inspect it. If you notice blackening, mushy roots, it has root rot. If you notice it still has healthy roots, you can try to save it. Cut away the diseased section of rotted roots with a sharp, sanitized knife. Treat it with an antifungal according to the directions. Repot it in fresh, well-draining soil in a sterilized pot.
Potting and Repotting
This tree is often grown in a container to use as a living Christmas tree. It can be moved outdoors in the early spring but needs to be hardened off by gradually exposing it to outdoor conditions.
A pot helps bind the root system. A pot-bound dwarf Alberta Spruce will grow slower and shorter than plants that have more room to grow. When repotting (usually every two to four years), make sure there is a 6-inch diameter available from the root ball so that it can be well-established. Use well-draining potting soil with ample drainage holes. These plants do not like overly wet soil.
Overwintering
If you keep this plant in containers outdoors, you will need to protect your dwarf Alberta spruce in the winter so it can survive. The biggest concern is the harsh wind chill that could permeate the potting container. To protect the plant’s potted roots, plant the pot in a yard or move the plant to an area sheltered from windy conditions. You can further insulate the roots by surrounding the containers with bales of hay or straw.
III. Uses and Benefits
White spruce ‘Conica’ is perfect as a distinctive specimen plant in the sunny border, cottage gardens, rock gardens or containers.