Blue Spruce is an amazing plant primarily because of its blue needles. Very few plants have such colors. In this article, you will learn everything you need to know about this plant.
Blue Spruce Care Tips
- Plant Blue Spruce in a location with 6-8 hours of direct sun per day.
- Water it as soon as the soil dries out 1 inch in the first 2 years after planting.
- Use a slightly acidic (pH 6.0-6.8) and well-drained soil for growing.
- Provide good air exchange near the tree.
- Prune Blue Spruce in spring or summer before the young branches mature.
- Place it 15 feet apart from other trees.
- Apply a multi-purpose fertilizer in the spring.
|Latin name||Picea pungens|
|Common name||Colorado spruce|
|Hardiness:||USDA zone 3-7|
|Size:||Height 40 ft. and Width 20 ft.|
|Light requirements:||6-8 hours of direct sun per day. Full sun or partial shade.|
|Soil:||Loam or amended soil.|
|Soil pH:||6.0-6.8 Grow best in slightly acidic soil.|
|Watering:||First 1-2 years after planting when the soil 1” dry.|
|Growth rate:||Medium (8-10 in. per year)|
|Best time for planting:||Early spring or early fall.|
|Spacing:||15 feet apart (center to center).|
|Transplanting:||Early fall or early spring.|
|Fertilizer:||Balanced NPK, slow-release.|
A place with a few hours of direct sunlight and drained soil is ideal for planting Blue Spruce. Also, make sure that no water flows near the tree (e.g. rainwater from a gutter). Also, there should be a few feet of space around the tree for good air movement.
It is best to plant or transplant Blue Spruce in March or April as soon as the soil has warmed up a bit. It is important that you plant this tree before the beginning of the growing season, in which case you can count on an almost 100 percent rooting rate. The second suitable period is the end of September.
Blue Spruce should be planted at least 15 feet apart from other trees or buildings. If you plant it too close you might have problems with disease or needle color.
The planting hole should be at least twice the size of the spruce root ball. First fill it with partially prepared soil, which we will talk about later. Then place the tree so that the place where the trunk meets the roots is not submerged in the soil. After planting, water the spruce with plenty of water.
Read more: How Do You Plant A Blue Spruce Tree?
Blue Spruce needs at least 5-6 hours of direct sunlight a day. In this case, you will get a tree with a dense crown and blue needles. This spruce can be planted so that it receives either morning or afternoon sun.
Also Blue Spruce can easily tolerate full sun. It can get direct sunlight all day long and nothing bad will happen to it. Moreover, in the full sun, its needles will be even bluer.
Placing Blue Spruce in full shade is contraindicated to it. Even dappled sun is not suitable for this tree. If it does not have access to the direct sun the crown will not be lush and the needles will be greenish. After a few years spent in the shade, the spruce will die.
Read more: How Much Sun Does A Blue Spruce Tree Need?
Blue Spruce tolerates a wide range of soils, the best is a well-drained but not too sandy soil. If you have clay soil, add organic matter to the planting hole to loosen the substrate a bit.
For sandy soil, the addition of organic matter is also positive as it will make the soil slightly moist and you will not have to water the spruce too often.
If you have loamy soil you do not need to add anything to it. It can be considered a perfect substrate for spruce. All you have to do is fertilize, but more about that below.
As for soil acidity, Blue Spruce likes soil pH 6.0-6.8. This tree grows well in neutral or slightly acidic soil. It can also tolerate highly acidic and alkaline soil, but in this case, the growth will not be as vigorous as it could be.
Read more: What Kind Of Soil Does Blue Spruce Like?
Water Blue Spruce as soon as the soil dries out 1 inch. Such watering is necessary before the tree is fully rooted. The rooting process can take one to two years. If the year after planting, the spruce has made good growth, you can consider it rooted.
Fully rooted spruce does not need watering at all. Exceptions are periods of extreme drought.
The amount of water should be at least 1-2 gallons. Water should reach all the roots of the tree. You can water in two stages, first soaking the top layer and then watering again to soak up the water to the maximum depth.
Avoid watering too often as Blue Spruce can get root rot. Constantly wet soil will cause the roots to become soft and begin to rot. It is almost impossible to treat root rot in spruce.
Read more: How Often Should You Water A Blue Spruce?
Blue Spruce is semi-dwarf spruce so it does not need pruning. But if you want to make it even more compact, you can trim it. The best time for pruning is in the second half of spring or early summer. You will need to cut before the young shoots mature, so cut them halfway. This will give you a thicker crown next year.
Sanitary pruning can be done in fall or early spring. Removing dead branches is good practice from a plant health standpoint.
Always use sterile tools, sharpening them beforehand. After pruning, it is a good idea to spray the spruce with a fungicide to prevent fungal infestations.
Read more: How Do You Prune A Blue Spruce Tree?
One of the reasons why Blue Spruce dies is root rot. The symptoms of this disease are the needles turning brown and then falling off. To fix this, remove all excess water near the spruce (frequent watering, high groundwater, etc.). There is nothing else you can do, if the tree is strong it will beat the disease on its own.
One of the most common problems with Blue Spruce is a fungal disease. This is especially true in an area with high humidity. Symptoms of fungal disease are black spots on the needles, as well as yellowing and falling off.
To cure the disease, make sure there is good air exchange around the spruce. Clean all dead needles and branches. Spray the spruce with an aqueous solution of copper-based fungicide. Repeat the spraying in a few weeks.
Read more: Why Are My Blue Spruce Trees Turning Brown?
One of the most common Blue Spruce pests is the Yellow-headed Spruce Sawfly. These insects have long, narrow bodies and long wings. They can travel considerable distances and infest a variety of spruce species.
The female lays eggs on spruce branches in the spring. When the larva hatches, it begins to feed on young, soft needles. A few dozen grubs can do a lot of damage to a spruce tree and make it look ugly.
To get rid of these pests, wash off the larvae with a stream of water and crush them. Next, spray the Blue Spruce with horticultural oil or neem oil. This will prevent new eggs from hatching and kill the larvae.
If nothing works, use a systemic insecticide several times at 2-week intervals. Although toxic, it is very effective.
A multi-purpose balanced fertilizer is best for Blue Spruce. Make sure the fertilizer is made into slow-release pellets. Apply it once a year in early spring before the buds begin to push. That’s it, now the tree has everything it needs for the whole season.
Avoid frequent applications as this can damage the root system. In this case, the needles will turn brown. Also, do not fertilize spruce for the winter as this can cause the tree to grow and frost will damage the young branches.
Another thing you can do is to mulch your spruce with compost. Compost is a good organic fertilizer that protects the roots from overheating and rapid soil drying. Make sure the layer of compost is no more than 2 inches thick and there is at least a 1-inch gap between the trunk and the mulch.
The only effective way to propagate Blue Spruce is by grafting, of course, if we are talking about propagating a variety. This way you can get an exact copy of the mother plant, i.e. all the varietal characteristics will be fully transferred to the new plant.
Unfortunately, it is very difficult to do this with our own hands. You will need quality plants on which the grafting will be done. You also need a sterile and ventilated greenhouse. The whole process can take several years.
It is also possible to propagate Blue Spruce by cuttings, but the number of rooted cuttings will be less than 10%. For this reason, this method is not commercially viable.
And the third way of propagation is by seeds. This way you will not get plants with varietal characteristics. Most of the seedlings will be green just like in the forest. But if you take seeds from an interesting variety, some seedlings may surprise you.
The best time to transplant a Blue Spruce is late February or early March, depending on the climate in which you live. You need to wait until the soil has thawed but the buds have not yet started to push.
A few days before moving, water the Blue Spruce with 2 gallons of water.
Choose a cloudy day as the plant can lose a lot of water in sunny weather. For the same reason, transplant in the morning or evening but not in the middle of the day.
Dig up the spruce as gently as possible. The fewer roots you damage, the easier it will be for the plant to survive the transplanting.
Gently move the spruce to its new location. Dig a hole twice as big as the roots. Fill it partially with a mixture of native soil and soil conditioner.
Place the Blue Spruce in the hole so that only the roots are buried in the ground. The trunk should remain above the ground. Fill all the empty space in the hole with the soil mix and water with 2-3 gallons of water.
Place a garden umbrella over the tree if the weather is too sunny. The umbrella can be removed after a few weeks.
Read more: How Do You Transplant A Blue Spruce?