The Juniperus scopulorum ‘Blue Arrow’, commonly known as the Blue Arrow Juniper Tree is a popular choice in many areas.
It is a Coniferous tree from the Cupressaceae family and is an attractive evergreen. It is also known as the Blue Arrow Rocky Mountain Juniper.
The most striking features are the blue-green color and the narrow straight columnar structure. A mature tree will reach a width of 4 feet (1.2 meters) and a height of around 12 feet (3.7 meters).
It has many uses in the garden as they are used for hedging, as accent plants, and pot plants.
- 1 Blue Arrow Juniper Tree Care
- 2 The origin
- 3 Blue Arrow Juniper Tree Care In-Depth Guide
- 4 Pests and diseases
- 5 Diseases
- 6 Frequently asked questions about the Blue Arrow Juniper tree
- 6.1 Why are my Blue Arrow Junipers turning brown?
- 6.2 Are Blue Arrow Junipers susceptible to root rot?
- 6.3 Will deer and other wildlife eat my young Blue Arrow Juniper saplings?
- 6.4 Does the Blue Arrow attract birds to the garden?
- 6.5 Is the Blue Arrow difficult to look after?
- 6.6 What type of garden is the Blue Arrow Juniper best suited to?
- 6.7 If I am planting the trees in a row, how far apart do I place them?
- 7 Conclusion
Blue Arrow Juniper Tree Care
The other benefit of the Blue Arrow Juniper Tree is that it is easy to grow and requires little maintenance. It can handle a range of soil conditions, temperatures, and water supply. So long as it has full sun and well-draining soil it is generally healthy and happy.
The tree does produce somewhat insignificant flowers but the blueish-silver berries that form towards the end of spring through winter add to the appeal.
The growth speed of the tree is medium, not slow but not exactly fast. A mature tree will grow roughly 15 to 18 inches (38 to 46 cm) per year. The average lifespan of the Blue Arrow Juniper Tree is 70- years.
The origin of this cultivar dates back to 1949. This is where it was selected as a seedling at the “Pine Grove Nurseries, Clearfield, Pennsylvania.”
It has become a popular choice among gardeners and landscapers and is often used as a substitute for the more common Skyrocket (Juniperus scopulorum ‘Skyrocket.’) This is largely due to the striking appearance as well as the ease of maintenance.
Blue Arrow Juniper Tree Care In-Depth Guide
Fortunately, the Blue Arrow Juniper is not too fussy about the type of soil it grows in. It can handle most soil types and a wide range of pH levels.
If you want it to be ideal, aim for slightly acidic soil. The only specific soil requirement is that it is well-draining. The roots do not want to stand in water.
If you are planting a new Blue Arrow from a garden center, it is always best to prepare and enrich the soil to give it an easier start. This will allow the plant to adapt to the new environment and start to grow with ease.
Planting the Blue Arrow Juniper Tree
Once you have decided on the location or locations for the planting of your new Blue Arrows, mark out the exact spots. Clear the area and dig a hole that is slightly deeper than the bag or pot it came in and twice as wide.
You can add some mulch around the sides of the hole but do not allow them to come into contact with the tree.
The mulch will help to retain water while the tree is establishing itself. You can also add a rooting aid such as Mycorrhizal root grow. Again, this just helps it to settle and adjust faster.
Remove the tree from the bag or pot and carefully loosen the roots. If they have formed a tight cluster from being pot-bound, you need to be patient.
Use a hose to loosen the roots if necessary. Place the tree into the hole and ensure that the trunk is planted to the exact same depth as it was before. Fill the hole with a mixture of half rich organic compost and half the original soil.
Firm the soil down. Do not create a mound or hollow, simply flatten the soil. Water the new plant immediately and then every few days for a few weeks.
You can replant at any time of the year although spring is ideal.
The Blue Arrow Juniper Tree can tolerate a wide range of temperatures once it is established. It likes full sun and can handle hot dry conditions but is also able to withstand cold winters. This makes it extremely versatile for a wide range of locations.
The plant zone is listed as suitable for zones 3 to 7. In reality, if planted correctly, it grows almost anywhere.
The Blue Arrow is often planted in areas that prove to be too cold for the popular Mediterranean/Italian cypress (Cupressus sempervirens). This variety does not handle cold winters while the Blue Arrow will come out simply fine.
Given the hardiness of the tree, it can be used in many locations. The main factor to bear in mind is that it wants full sun. As we have mentioned above, you also want an area where the soil drains well. A boggy marshy area will not be suitable.
The Blue Arrow Juniper Tree is highly versatile. The neat and attractive columns make it ideal for screening.
It will make a spectacular display when planted out as a privacy hedge. The shape and color also make it a great accent plant particularly if you are looking for a vertical accent in certain areas. It also looks good in general garden positions alone or in clusters.
Another way the Blue Arrow Juniper Tree is used effectively is in pots. This will obviously inhibit the growth of the tree, so it is best to go for pots of a decent size.
Ensure the pot has drainage and is positioned in full or near to the full sun. The rest of the care advice will be the same for potted trees, but they might need a bit more watering than those in the ground.
The root system of the Blue Arrow is not invasive like many trees but will spread as it searches for water.
Do plant it too close to boundaries, walls, or paving. The fibrous roots could potentially cause damage to structures that are very close to the base of the tree.
How to take care of the Blue Arrow Juniper Tree
These are low maintenance trees that, once established, need extraordinarily little care or treatment. They are hardy, tough, and resilient.
Here are the main things to keep in mind when caring for your Juniperus scopulorum ‘Blue Arrow’.
A newly planted tree will require regular water until it is well established. Once the Blue Arrow is happy it will be tolerant of most conditions.
It can handle lots of water while it is also drought tolerant. The key is to have well-draining soil as it does not like to stand in water.
If water is not an issue and it has been a particularly dry spell or an extended hot period, it might help to give your tree a deep penetrating soak every so often.
Do not simply splash water around the base as this will do more harm than good. Let it soak deep into the soil.
In extremely hot dry areas, it is wise to add a layer of mulch around the drip line of the tree. Not only will this help to keep moisture in but also prevents weeds from growing at the base of the tree.
Trees planted in pots will require water from time to time. Again, ensure there is good drainage. If the tree is not getting rainwater, give it a good watering once every 7 to 10 days, more if it is extremely hot.
Being a tough hardy plant there is little need to fertilize the Blue Arrow excessively. All plants need nutrients so feeding the tree can only help to make it more robust and attractive.
A slow-release organic fertilizer or all-purpose fertilizer can be used to enrich the soil around the base of the tree from time to time. Two to three times per year should be more than enough unless you have particularly poor soil that is low in organic matter and nutrients.
You can give them fertilizer at any time of the year, but early spring and summer is the most important time. Do not place the fertilizer close to the trunk as this could cause root burn.
Feed potted Blue Arrows the same way.
There are two ways to propagate the tree, cuttings, and seeds.
Propagation from cuttings
The Blue Arrow Juniper can be propagated from cuttings. The process can take some time and patience but is not that difficult provided you follow the correct process. The best time to take cuttings is in summer.
Select a healthy plant and look for new cuttings that are just starting to harden but not yet too woody. It is recommended that you take many more cuttings than are needed as your success rate will not be 100-percent.
Take the cutting in the morning and pot them immediately.
This is the process that needs to be followed:
Prepare the soil for the cutting in advance. Use perlite and peat moss in equal amounts in a large container and add water. Mix the soil and water and allow half an hour for the water to be absorbed. You want a wet consistency but not a runny mixture. Add more water if necessary.
Use a pot that has a hole for drainage. A 6-inch plastic pot is ideal. Fill the pot with the mixture you have prepared.
Using sharp shears that have been disinfected, cut off a length of roughly 6 to 8 inches. Remember to look for healthy new growth that is just starting to harden.
Remove all the needles from the lower third of the cutting. You can cut shallow slits in the exposed stem to aid in water and rooting hormone absorption.
The clean tip of the cutting end needs to be dipped in a quality liquid or powder rooting hormone. Use the product according to the directions. Ensure you are using the correct root hormone for semi-hardwood cuttings and that the tips are coated generously.
Push the coated end of the cutting into the prepared soil mix. You want to insert it to a depth of between a third and half of the cutting. Using a spray bottle, mist the cutting and secure a plastic bag over the pot. Use clear plastic and ensure it is kept away from the cuttings.
The cuttings need to be placed in a warm and bright environment but not in direct sun. A temperature of 60º to 70º F is ideal.
Remove the bag and mist the plants daily and add water to the soil mixture if it becomes dry.
Only take the bags off once new growth is visible. The cuttings could take as long as 6 to 8 weeks to root.
Propagation from seed
This is a delicate and intricate process that takes time and effort.
This is the process to propagate the Blue Arrow Juniper tree from seed:
The Blue Arrow produces berries, and these are mostly found in winter. Collect the fresh ripe berries. Select healthy berries that are undamaged and that are ripe.
You then need to soften the outer layer. Do this in a solution of 1 gallon (3.8L) of water to a teaspoon of . Leave them to soak for a day or two. Remove, rinse, and allow to dry.
Using a mesh, remove the pulp by rubbing the softened berries. Place the extracted seed into a bowl of water. Use only the seeds that float as those that sink will not germinate.
The next step is to boil a pot of water and turn it off once boiling. Place the seeds into the hot water. This will scarify them. Once the water has cooled remove the seeds and allow them to dry again. Another way to scarify the seeds is to rough them up with a file or sandpaper.
Place the seeds into a resealable bag that has been half-filled with moist sand or peat moss. This needs to be placed in a warm area, ideally, between 68 and 86º F. Ensure it stays moist and mist if necessary. These need to be left for 2 to 6 months.
The bag then needs to be refrigerated at about 41º F for 3 to 6 months.
Once this stratification process is complete, plant the seeds out into a seed tray. This should be filled with potting sands or moist peat moss. Insert them to a depth that is the same as their diameter. Cover the tray with plastic wrap to keep the moisture in.
The tray should be placed in a warm bright area but not in direct sunlight. Once the seeds have started to germinate the tray can be moved into more direct light.
When they have grown to the size of the tray compartments they can be potted out into larger pots. Ensure these have good soil and drainage and water every few days.
Once they are established and healthy, they can be planted out into the garden. This is best done in spring.
Most people will find that the Blue Arrow Juniper Tree needs little to no pruning. If it is looking scraggly or there are unhealthy parts or untidy branches sticking out, you can cut these back to neaten the tree up. This can be done as and when they are noticed.
The only time that pruning is essential is if your tree is diseased. If you cannot treat the problem quickly and effectively you want to prune back the infected area as well as the area surrounding it. This will prevent the disease from spreading further. Destroy the pruned material.
If you find you are having a problem with disease control it could be a lack of airflow. In this case, prune selected areas to thin the tree out and improve ventilation.
If you are growing the tree in a pot you might want it to be closer to perfect. You can train the growth from a young age.
In spring, cut back the terminal tips to maintain the think upright profile of the Blue Arrow. This thins the tree out slightly to open it up and remove any dead or dying growth.
Pests and diseases
While a healthy Blue Arrow is tough and resilient, they are not immune to pests and diseases. One needs to keep an eye out for certain problems.
The main pest concerns are the juniper scale, Spruce spider mite, and bagworm. Aphids and caterpillars could also be a threat in some areas.
Twig blight and canker are the main diseases to watch out for. There are a few others that are also a potential threat. We will look at each one in turn.
Juniper scale (Carulaspis juniperi) presents with remarkably similar signs to spider mite. Once infested, needles on the tree will turn brown or yellow after a while. Entire branches might start to die. When left untreated it looks unpleasant and the infestation could kill the tree in a few years.
You need to inspect the tree regularly, particularly if you notice any signs of distress or discoloration. The scales are exceedingly small, often looking like tiny bumps. They are more common on the underside of infected needles.
They can be white, gray, or black, depending on their age. They also generally leave a sticky trail known as honeydew.
Over time, this secretion builds up and leaves dark shiny patches over the needles. It normally attracts ants.
This needs to be treated with an insecticide specifically for scale or Juniper scale. It is important to inspect the tree after use and reapply as required. This might need to be done several times to remove the problem.
Spruce Spider Mite
Another problem is spider mites specifically Spruce spider mites (Oligonychus ununguis). These pests are small and hard to detect.
The mites suck sap from the tree with sharp mouths. Small yellow spots are often visible after they have been feeding. This is easier to notice than the mite itself. You may also see brown or dropping needles.
After a while, small “webs” might be noticed. Again, this infestation makes the tree look unsightly and could eventually kill it after a few years.
Unlike normal spider mites that appear in the hot dry season, Spruce spider mites are more prevalent in cold times. They are often controlled by predators in the warm summer months.
For this reason, you want to try to avoid insecticides if possible as these will also kill off natural predators such as ladybird beetles. Killing these predator insects could make the problem worse in the long-term.
Fortunately, there are insecticides available that will help to control the Spruce spider mites while causing minimal harm to their predators.
Look at the label carefully and do your research. Another way to treat the problem is with a strong jet of water. This might need to be done frequently to be effective.
A serious infestation might require a stronger insecticide. Place a sheet of white paper below a branch and hit the branch.
You should be able to see the mites on the paper. If there is a significant number, the tree is at risk. Select a pesticide specifically for spruce spider mite and inspect it regularly. Reapply until you are sure the problem has been sorted out.
Bagworm (Thyridopteryx ephemeraeformis) is another pest that enjoys conifers and is sometimes a threat to the Blue Arrow Juniper Tree.
A bad infestation will eventually kill the tree while milder amounts simply inhibit the growth of the tree.
The moths are relativity small with the female being yellow and the male dark and hairy. The larva has a silk bag that tapirs at the end.
This fills with plant matter as the larva eats. It grows up to around 2 inches.
When the larva emerges and mate, the female can produce as many as 1000 eggs before dying.
Again, these pests have several natural predators that help to keep them in check. You can also manually remove and destroy them when spotted.
If the infestation is severe a bacterial insecticide should be used. Follow the instruction on the product for the best results.
As with most pests, the best defense is to keep the tree healthy. Aphids generally prey on weak stressed trees.
Most people are familiar with aphids and they should be easy to detect and identify. The aphids that attack junipers are larger and darker than average aphids.
They also leave a trail of honeydew as they eat and again, this often attracts ants.
The first type of treatment advisable is to manually remove the aphids (and the ants if present) by hand or with a strong jet of water.
If this is unsuccessful or the infestation is rampant, buy an aphid specific insecticide and use it as directed.
This is identified by browning or graying of the tips of the branches. It sometimes spreads deeper down the branch. This needs to be treated by pruning all areas that are infected. Removed material should be destroyed, and a fungicide applied to new growth.
There are several types of canker that affect different plants and trees. The main one that attacks Junipers is known as Seiridium or Cypress canker. This is a serious disease that can cause extensive damage.
Part of the challenge is that it can take a year before any signs of infection are visible. You will eventually see browning or yellowing as branches die.
The canker then spreads to other branches. Untreated or left too late the tree can die.
Below the affected branch you might find a red-colored area sunken in. This often contains fruiting matter, blister-like lumps, and bumps.
These are known as pycnidia. When it is wet, they open and sap drips from the edges of this area. Infectious spores are released when this happens and the canker spreads.
Infection can be caused by animals or insects that have eaten part of the tree or from garden equipment that has cut or damaged an area. Hail and bad weather are other potential causes.
In some instances, the canker is contained and does not spread. It can simply be removed, and the infected parts destroyed.
It is also more likely to affect plants that are stressed and unhealthy as a result of drought or other stress factors.
There are no chemical means to control this disease. It must be done manually by removing the affected parts as well as the area immediately above and below the infection.
If the tree is badly infected and the canker has spread, it is best to remove the tree altogether.
There is some evidence that fungicide that contains macozeb could reduce the chance of infection and possibly slow the spread in an infected tree.
The best way to prevent it is to ensure the plant is healthy and has sufficient nutrients and water. You also want to ensure it is not damaged by garden equipment or wildlife. When cutting or pruning ensure the equipment is sharp and sterile.
Frequently asked questions about the Blue Arrow Juniper tree
Why are my Blue Arrow Junipers turning brown?
There could be several reasons for this. Diseases such as twig blight are one of the reasons or it could be a pest infestation such as spider mites or scale. See the section on diseases and pests above to identify and rectify the problem.
Although rare, it could be due to a nutrient imbalance if the soil is particularly poor. Soil can be tested to see if this is the case and a quality well-balanced fertilizer will remedy this problem.
Are Blue Arrow Junipers susceptible to root rot?
This is very unlikely but possible if the soil is soggy and has poor drainage. The trees are tolerant but do not like to have their roots wet for extended periods. Make sure the area you plant has soil that drains well.
Will deer and other wildlife eat my young Blue Arrow Juniper saplings?
While this is often a problem it is fortunate that deer and most other grazers normally avoid the Blue Arrow.
Does the Blue Arrow attract birds to the garden?
Birds are especially fond of the berries that grow from late spring through to winter.
Is the Blue Arrow difficult to look after?
While it is not indestructible it is extremely hardy and tolerant of a range of conditions. It is not too fussy about the soil quality, water, and temperature. It is also tolerant of pollution. Full sun and decent drainage are the main things you need to ensure.
Once established there is little work to do and the Blue Arrow will give pleasure all year-round.
What type of garden is the Blue Arrow Juniper best suited to?
It will look great in a range of garden styles and is an extremely versatile tree. It is popular in Mediterranean styles, formal gardens, and Zen-style environments.
Many people use one or several Blue Arrows to add height and create an accent spot in the garden. They can also be used for privacy screening and hedges.
If I am planting the trees in a row, how far apart do I place them?
If you want to create a screen effect, plant them 3 feet (1 meter) apart. This is measured from the center of the trunk.
The Blue Arrow Juniper Tree will look good in most gardens which is why it is such a favorite with professional landscapers as well as gardeners. It has a variety of uses and looks great all year-round. What is more, is that it is a low-maintenance plant that is easy to grow and care for.
You have little to worry about when it comes to climate, watering, soil, fertilizer, pruning, and even pests and diseases. If you do not already have any, consider adding a few Blue Arrows to your garden.
Given the popularity of this tree, they are normally quite easy to find and pricing is reasonable. Invest in a few Blue Arrows, you will not regret it.
Marcel runs the place around here. He has a deep passion for houseplants & gardening and is constantly on the lookout for yet another special plant to add to his arsenal of houseplants, succulents & cacti.
Marcel is also the founder of Iseli International Commerce, a sole proprietorship company that publishes a variety of websites and online magazines.