Why Is My Juniper Bonsai Turning Yellow?

Junipers are a great tree for bonsai and they are evergreen, meaning they should be green all year round. If you suddenly find that your juniper bonsai turning is yellow it can be pretty worrying.

You need to work out what is wrong and you need to do it quickly. Sometimes yellowing on a juniper is nothing to worry about, while a lot times it can indicate a big problem and you tree could very quickly get worse and ultimately die if you do not try and fix the problem.

While I can’t tell you exactly what is wrong with your juniper, I can explain the common causes of yellowing in juniper bonsai and you can try and work out if any of these are the cause of your issue.  

Old Foliage Dying Back Will Turn A Juniper Bonsai Yellow

As junipers are evergreen they don’t lose their leaves in autumn, but their foliage can often get old and is no longer efficient for the tree, so they will shed it, which means it can turn yellow and brown before dropping off.

This is more common in needle style junipers, where you will see the older needles being shed, but it can still happen with scale foliage too.

This is nothing to worry about and is just the tree getting rid of some older parts it no longer finds useful. If the rest of the tree is looking healthy and growing well, and you can clearly see that it’s just old growth from a few seasons ago, you don’t need to worry. It just looks a bit ugly, but it’s fine.

Inner Foliage Turning Yellow

If you start to notice the inner foliage on your juniper bonai turning yellow, it probably means it is not getting enough light to those areas.

This can be a sort of problem, but it depends what you are trying to achieve with your tree.

If you are noticing this problem then your tree is probably looking a little bushy and the outer foliage is probably looking very healthy and therefore blocking the light to the inner parts. You probably want to trim this a bit to let some light in to the inner structure.

While you might not be worried about keeping the foliage in there, it is better to allow light in. A lot of the foliage in the inner areas will be old or weak, so it will shed at some point anyway, but that’s not the point. There will still be a lot of dormant buds in there and you don’t want them to die.   

You want to make sure these buds get light so they can grow in the future. If you want your tree to become more compact you will want these buds to grow, so you can cut back to them and reduce your branch lengths.

Do Juniper Bonsai Turn Yellow In Winter?

Junipers are evergreen, so we don’t expect any change during the year, however, that isn’t always the case.

Juniper bonsai are not going to drop their foliage like a deciduous tree, but you may find they turn a different colour.  

It will depend on what species of juniper you have but they can go a slightly different shade of green and even start to turn yellow or even brown in colour during winter. Some species of juniper even get a sort of purple tint to them.

This can all look pretty troublesome, especially if they go a sort of yellow or brown colour, but this is totally natural and is just a reaction to the cold weather.

Once spring comes they will change back to their more usual shade of green. Just wait it out and everything should be alright. 

Poor Pruning Will Turn A Juniper Bonsai Yellow

If you prune your juniper bonsai poorly, your tree may turn yellow, although it is usually more of a brown colour.

This happens if you cut through the foliage in the wrong place, such as through the foliage itself, rather than in between it.

This makes more sense if you think of needle junipers, and you cut the needle in half, rather than cutting just below the needle and removing the whole thing.  Cutting through like this will cause the area to go brown as it heals.  

This will also happen if you have blunt scissors. If they are blunt they do not cut cleanly, they basically crush the tree and tear it off, which damages the area and causes it to also turn brown.

If you have done this, it is nothing to worry about. Your tree will just look ugly for while, but you should make sure your tools are sharp and that you know where you should be pruning in the future.

Stress Will Turn A Juniper Bonsai Yellow

If your juniper bonsai is stressed in any way it is probably going to result in the foliage turning yellow. This not good and you need to fix the problem.

If your tree remains stressed it is only going to become weaker and ultimately die. Everything I discuss below is a form of stress for a tree, so your problem is likely going to be one of, or a combination of the points below.

Water Problems Will Turn A Juniper Bonsai Yellow

Getting watering right is very important. If you get this wrong you can very quickly kill your tree and the yellowing of the foliage can be a sign that you are doing it wrong.

Under Watering

If you do not give your juniper enough water it is going to dry up, turn yellow and die. This can happen pretty quickly, so you really do not want your tree to dry out.

If you your tree is yellow and bone dry you need to water it quickly. There is a very strong chance your tree is dead, but you just have to try and water it and hope it didn’t dry out to much.

Over Watering

Over watering can also make the foliage of a juniper turn yellow, but this problem usually takes longer to show itself.

If your tree is constantly sat in water it will basically drown. The roots will start to rot and die and then tree has no roots to take up water and you will start to see the yellowing occur.

You will need to stop your soil getting so wet if this happens and then look to repot into better soil in the spring.

(You can read more about – What Is Overwatering A Bonsai Trees?)

Bad Soil Will Turn A Juniper Bonsai Yellow

Bad soil can cause your juniper bonsai to turn yellow, but this is usually because it is either drying out too fast or is staying wet for too long, which of course means you are going to end up with under watering, or over watering, which I just talked about above.

You want a bonsai soil that is going to drain quickly, but still hold some dampness. This will stop the soil being too wet or too dry and help you avoid the yellowing of the foliage.

Humidity Will Turn A Juniper Bonsai Yellow

Humidity is not really a problem for junipers, it’s more the lack of it, which is what you will find in your house.

Junipers should be grown outside. Most people who grow them inside usually start to see yellowing and this is normally from them being too dry.

It can be sometimes be from a lack of light, but I think most people do try and place their tree near a window, the issue is that most homes have radiators under the window. All that hot dry air is not what a juniper needs. This will probably kill your tree, let alone turn it yellow.

 If you are growing your tree outside you are not going to have this problem.

(You can read more information about – Can You Grow A Juniper Bonsai Tree Indoors?)

Lack Of Light Will Turn A Juniper Bonsai Yellow

A lack of light will cause any trees foliage to go yellow, especially junipers. Again, if you are growing your tree outside this probably won’t be an issue unless you have you tree in constant shade, or your outer foliage is blocking some of the inner growth like I talked about at the start.

Most cases of a yellowing from a lack of light come from people growing indoors and having their tree nowhere near a window. If your juniper is inside, it really needs to go outside.

A lot of bonsai trees can also burn if they get too much sun, which can turn them more brown, than yellow. Junipers do not really suffer from this. They are pretty tough and do enjoy the sun. So long as they have enough water, too much sun should not be an issue for them. 

(You can read more information about – How Much Light Does A Bonsai Tree Need?)

Lack Of Nutrients Will Turn A Juniper Bonsai Yellow

Junipers will react like any other tree and turn yellow when they have a lack of nutrients. This isn’t very common as most people growing bonsai trees tend to fertilise their trees often, arguably too often.

If you have your tree growing in poor soil, or if it has been in the same soil for a number of years, then it may be slightly deficient in some nutrients, especially if you have not been fertilising.

Some fertiliser will quickly green your tree up, but you should really make sure you have ruled everything else out first. Fertilising a tree that is weak from some other cause can harm the tree more. fertilising a weak tree can overwhelm it and an make it worse.  

Root Problems Will Turn A Juniper Bonsai Yellow

A lot of yellowing in juniper bonai can be caused by the roots. Juniper roots are quite fussy and you have to be careful when working with them.

Over Pruning Roots When Repotting

When you are repotting a juniper you need to careful with the roots. You cannot just hack them back like you can with a deciduous tree.

Taking too much off can seriously weaken the tree and can cause yellowing. However, it usually causes these areas to actually die back, as the tree just hasn’t got the roots to support the top the tree. 

Root Rot

I’ve already touched on this in the watering section, but basically if your tree is too wet, the roots can rot. This means they start to die and then when a tree has no roots; it can’t send water up into the tree, so everything starts to turn yellow and die.

As I said before, you need to deal with this and make sure the rot is not getting any worse. Really the tree needs repotted into good soil and the dead roots removed. This is extremely stressful for a tree and its chances of survival can be very low.

(You can read more information about – Root Rot In Bonsai (What Is It? and How To Fix It))

Junipers That Are Pot Bound

As juniper roots are sensitive we tend to wait a while to repot. We may not repot them as often as a deciduous tree. This means there is more chance for the tree to fill the pot up with roots and get pot bound.

When this happens the pot is so full that water struggles to get into the pot. This results in the tree acting like it is under watered and it can turn yellow.

If your tree is pot bound you will have to repot it in spring, but until then you will need to make sure that you are watering more and really trying to get as much water into the pot as possible.

Over Working A Juniper Bonsai Will Turn It Yellow

Junipers are sensitive and you can not over work them. While they can take a lot, they do get stressed by bonsai work, especially if you do too much at once. 

You should try and space your work out. don’t prune, wire and repot the tree all on the same day, it’s going to be too much for it and stress it out, which can lead to yellowing of the foliage.

Do some work and then give the tree time to recover before doing the next procedure. You just need to take junipers slow and steady.

Pests and Disease Will Turn A Juniper Bonsai Yellow

There are plenty of pests that are attracted to junipers and they can cause yellowing of the tree. Usually they do not directly cause the tree to turn yellow, but their attacks can weaken the tree, which can in turn make the tree so stressed that it turns yellow.

You should be checking your tree often for problems and dealing with them as soon as possible. If you leave it your tree will only get weaker and can ultimately die.   

Conculsion

As you can see there are a lot of things that can cause a juniper bonsai to turn yellow. Some of these are harmless, but a lot of them are not.

Basically if your tree is stressed it can turn yellow. You need to work out what is causing the stress and then correct it. If you can do this quickly enough your tree should be able to recover and bounce back to full health.

I have two junipers and you can follow their progressions – Pftitzer Juniper Progression (2017-Now) and Squamata Juniper Progression (2017- Now)