The fantastic Juniperus procumbens nana

The following article was written by Brett Simon

Introduction

This shrub is native to the southern parts of Japan. Commonly known as the garden juniper, it is a fantastic species for bonsai. They are mostly used as trees for beginners. Most of the new talent comps around the country use these as stock trees to work on. I know I have worked on a few and was in fact one of the first tree I ever bought and owned as a bonsai.

In Japan they are not very common as bonsai as they are thought to be too easy. I personally have never understood this. It grows well in all parts of South Africa, takes easily from cuttings, is easy to train and transplants well. What more could a bonsai grower wish for!!

Juniperus procumbens is a mounding juniper. This means that it needs to mound up foliage first before it will elongate. If we need to lengthen a branch we need to let the foliage build and mound before it will send out a runner.

Insert: Note how the foliage at the base of the elongated shoot has mounded up. This strength allows the shoot to elongate.

Juniper's strength comes from there foliage. This means that extra energy is stored in the foliage. For this reason we should never remove more than 70% of the foliage in one go. Please note that this is for a healthy tree. Removing 50% of foliage from a sick or weak tree may cause it to die. I have seen growers do this and the tree was fine however we are taking a chance by doing this. We always need to treat the tree the best we can. So to be cautious stick to 50% at most unless you feel confident that you know the tree will bounce back well.

Cuttings/Air layering

Cuttings can be taken at most times of the year but I have had best success in late spring. I have taken cuttings as thick as my thumb and they have grown well although best is that about the thickness of a pencil. The only time I would not try cuttings is in the middle of winter.

I use akadama and pumice for my cuttings in a 70/30 mix. I have at least a 90% success rate. I don’t use any rooting hormone although I am sure it will not hurt to try.

Air layering is best taken in summer. Always leave some green below the section where you plan to take the layer. This will allow sap flow to continue. Roots normally form within a month or so. Once the bag or pot you used is full of roots it may be separated. I usually wait till the following spring to do this. Make sure you use a black bag to cover your layer this will help prevent algae from growing.

What to do and when?

I have been asked many times what to do when on a juniper. Below is a timeline of when is best to do the following. Please note that I will never give a date as we live in a country that is vastly different. You need to watch your tree and it will tell you when. I have given about times by season.

Styling /Repotting

The first thing to note is that the best time to style a juniper and to repot a juniper is the same. However you cannot perform both in one season. If you need to do both I would repot first and let the strength from the foliage build the new roots and following season you can style, provided the tree grew well.

The best time of year to style a juniper is late winter/early spring just before the new growth starts. The tree will start to “green up” from its winter dull colour. We can do heavy bending and reduce foliage at the same time, as the new spring push will let the tree recover.

If you plan to do heavy bends on main branches it is a good idea to first wrap that branch with Raffia. Always remember to wrap the raffia in the same direction as you are going to apply the wire. Clockwise if you are bending to the right and anti-clockwise if you are bending to the left. I prefer to use copper wire on junipers as I can use a thinner gauge to hold the branch. Just remember that you must use a wire that will hold the branch in place once it has all the new growth on. If you use a wire that is too thin it will start to drop as that branch gets heavier with all the new growth. Leave wire on until it starts to bite in.

Be sure to catch Brett's video on heavy bending of junipers here.

Late winter/spring is the same time that repotting is best carried out. Once you start to see the new growth emerge, this is the best time to carry out repotting. If you repot do not remove foliage. The stored energy in this foliage will help the tree build new roots. You should never bare root a juniper. Always leave a portion of the old soil. If it is in really bad soil you can remove half that bad soil in one repot and then the next time you repot remove the other half.

The second best time to style a juniper is early autumn as the second flush of growth hardens off. Again this would be the second best time to repot if needed.
The reason this is a good time is that the cambium is thickening which causes wounds to heal quickly. Note that not as much work can be done as in spring.

Insert: Before styling in spring. Tree has been allowed to grow freely. Foliage has built up and the tree is strong.

Insert: After initial styling. The tree had much of the foliage removed and two major branches were removed and made into jin. The roots were not disturbed at all. Wire was placed only on structural branches. In this case many of the strong growing tips were left on the tree so that growth could continue.

Yes the previous owner had grown that cascade branch for 15 years but I had seen a much more compact tree inside.

After the initial work the tree was fed well and allowed to grow freely. The more foliage it put on the stronger it became. The deadwood was left untreated to dry out.

Insert: Two years later the tree was repotted into a growing pot. After it recovered it was given a styling to begin building the pads. Note this was done in autumn as the tree showed good growth after the repotting done in spring.

The following year it was allowed to grow freely. Only trimmed to keep shape.

Insert: After a year of feeding and light trimming the tree was ready for another styling at the beginning of spring.

Insert: The tree after the styling

After four years of building the tree and maintaining it, it was ready for display. All that was done in these four years was to follow the yearly cycle as described.

Insert: The tree on display only four years after first work started. The only thing now was to get it out of the training pot as it looked way to big for the tree.

After another year the tree was finally put into a pot which I felt suited the tree.

Deadwood/Creating Shari

Deadwood can be cleaned at any time of year. A simple scrub with water and a toothbrush will remove any algae. We can then treat with lime sulphur.

Bark flakes on junipers when it is old. This makes a perfect hiding place for insects to hide. Removing the flaking bark helps to minimize this. Peel away the flaking bark with a sharp scraper. If you hit “white” then stop. Little nicks of the live vein will heal over quickly. If you wish you may then scrub the new bark with a brass brush, this will cause the bark to redden which looks great against the white deadwood (this is a matter of opinion, each to their own).

If we want to create Shari (deadwood along the live vein) or simply widen the deadwood it is best done in late summer/early autumn. The reason being is that the cambium is thickening, which in turn heals the new cuts very quickly. A good idea is to apply putty type wound sealant along the live vein to stop it from drying out. We don’t want to do this during spring and summer as the sap flow is strong and the cambium separates from the hard wood very easily.

Pruning

Always prune junipers and never pinch. The constant pinching will weaken the tree over time. Try cut between needles and always back to a growing tip.

Always cut to two branches, any more in one junction and the branch will swell. This process is called bi-furcation. Simply put it is 2 branches, which become 4, which become 8, each time splitting into two. In three years you can have a very ramified branch.

After the spring growth hardens off (the new light green foliage starts to take on a darker green) we can prune to help shape the tree. This waiting till the foliage has hardened off also allows the tree to rebuild its strength after using much of it in the spring push. The tree will then put on a second growth. This second flush is not as strong as the first and should not be trimmed again till autumn.

Maintenance

In early autumn it is a good idea to “thin” out the foliage. We remove all weak growth that has no growing tips. This foliage is actually using more energy than it is giving back to the tree. We remove crotch growth (the only time we keep crotch growth is if you have a long branch and need foliage further back, we then use this growth to cut back too. It must however get strong enough before cutting back to it).

The reason for this is to allow light back into the tree. If this is not carried out we end up with an overgrown bush in a year or two. By opening up space we allow the light into the inside branches which in turn encourages back budding. This back budding can then be used to cut back to so we can keep the shape of the tree. If we don’t the tree will just get bigger and bigger.

When cleaning the tree it is also important to clean the underside of the pads. This gives a crisp feeling and defines the pads. The following pictures show what has just been done to the tree. It is now autumn and time to carry out maintenance.

Insert: The tree after strong growth this season. If left many of the internal branches will die due to lack of light.

Insert: The tree after cleaning up the pads. Notice how the under side of the pads are flat, defining the pads. Also note that the deadwood has been cleaned and that lime sulphur has been applied. Also cleaned the pot for good measure.
There was no wire used in this process. Just by cleaning we have given shape back to the tree.

Common faults

I have seen many procumbens nana that have been made into bonsai with the following “faults”. This makes the tree look artificial and man made. We need to try and steer clear of these faults or redesign a tree that has them.

The first and most common is the cascade style of this species. Procumbens naturally like to grow down, they are after all a ground cover juniper. The fault comes in when the first bend going down on the cascade branch is a loop or curve and not a sharp angle. A branch that comes out of the trunk at more than a 45 degree downward angle is considered natural. I see too many that have been wired down and a semi circle or loop has been formed. Watch out for this. This is a fault that starts at the beginning of the tree and is hard to rectify.

The Herringbone look is another. Remember that at any one junction there should be only two, the trunk is considered one. This means that only one branch should come out of the trunk at any one point. Also try to stagger branches left to right and try and differ the spaces between them.

Allow branches to thicken up. The previous owner of the tree above took 15 years to get that cascade branch to thicken to the right size (he has forgiven me). This makes the tree look in proportion. I often see I trunk that has all the branches coming off it too thin. Take your time, you will be rewarded in the long run. I have rushed this before and ended up with a tree that looked ok but those thin branches always bugged me. I eventually cut the tree back and started again losing so much time.

Want to read some tips for better junipers? Find them here.

Conclusion

Juniperus procumbens is a fantastic tree for bonsai whether you are a beginner or an experienced grower. There are so many design possibilities and the tree is very forgiving. If a juniper procumbens is treated correctly the needle foliage will actually become scale like foliage. The tree above has much of this and my goal is to see how much I can convert to this. It is not very difficult. Follow the steps at the right time of year as above and you should see results.

Be sure to view my Juniper gallery for more inspiration.

Happy growing!

Brett Simon is a prolific bonsai artist and grower in the Western Cape of South Africa. He has and continues to contribute much to the local bonsai fraternity. Not deterred by convention, Brett loves to experiment with techniques and species. His enthusiasm is contagious and I am certain you will look at your procumbens junipers differently now.