Chinese Elm Bonsai Tree Care Guide

Ulmus Parviflora

Chinese Elm bonsai trees are probably the most common kind of bonsai and generally the first one most people will own. Without some information on how to look after them, they are also usually the last ones they will ever have after they struggle and then finally give up.

They are tough and able to survive the hazards of life indoors, difficult for any tree. Chinese Elm has very small leaves, rugged bark, fine branches and nice roots. Large trees have real charisma and the wow factor. Small ones can be bought cheaply.

The tree is semi-deciduous and will either keep or partially loose its leaves depending on the conditions in which is it kept.

Location

To my mind, location is the biggest factor in success when keeping bonsai trees indoors. A coffee table isn’t going to work in the middle of a sitting room. A bookshelf will be too dark. Almost everywhere that you see them in films and on TV won’t work, the bonsai tree has been put there for the filming. Sorry to burst the bubble, but it’s quite true.

Bonsai require a bright position, if you are going to keep one in the house please avoid dark corners. Indoor bonsai trees want plenty of light, so a bright sunny windowsill works well. The main problem with this is that in summer, it will be very hot. ideally, you want the light without the heat, which is hard to do.

Solutions to this problem include bigger pots, bigger trees, drip trays, mist spraying and moving the bonsai tree in summer. A bigger pot relative to the tree will provide a larger reservoir of soil, meaning that the tree will dry out less quickly and that the moisture in the soil evaporate, making the air around the tree more humid.  A bigger tree is more robust generally, as they have more roots. A drip tray underneath the pot will collect some water and more humidity. Mist spraying will again increase the humidity (you get where I’m going here – they like a humid environment.) If you can, a few months outside will help a lot, do this in summer, to avoid the dry, hot window in summer.

I sometimes say to customers “When you go into the garden in spring, take the bonsai tree with you. When you come back in at the end of summer, bring it back in”.

If outside, the tree is not fussy. I grow them outside in full sun, partially sun and full shade. They are all very happy.

When I first started growing bonsai trees, I used to think that Chinese Elms were sensitive to the cold. Over the years and with experimentation, I have found that they are amazingly hardy trees that can withstand cold temperatures down to around minus ten degrees. The big plus in growing them outside this that the leaves are much smaller and the growth is much tighter, as they the not putting out big leaves in an attempt to hoover up as much light as possible.

“Do you remember that horrible winter a few years ago when it dropped to minus 15? That is the only winter that I have lost Chinese Elms to the cold.” Another shop quote.

Watering your Chinese Elm Bonsai Tree

Aim to maintain an even level of moisture. Balance is key. You can rot plants’ roots through too much water. Equally too little water has more obvious consequences. If the leaves curl up and go dry and crispy, this is a sign of drying out.

Indoors, the most simple way to water is with a cup or jug. Just pour water onto the soil surface. Water until water runs out of the holes in the bottom of the pot. Most of the roots are in the bottom portion of the pot, so if you only give them a bit of water, the top will look wet, while the majority of the roots are actually dry.

You can also dunk the whole pot and soil in a bowl of water in order to make sure that you haven’t missed any part of the root mass. After that, leave it to drain on the kitchen drainer or outside.

What about mist spraying?

Yes, some people do this, the idea being to increase the humidity around the tree. It will increase the humidity around the bonsai. I need to point out though that I have had Chinese Elm bonsai trees growing on my south-facing kitchen window for years and have never ever mist-sprayed them.

Pruning your Chinese Elm Bonsai Tree

“Will I have to prune it?” is a frequent question I get asked asked at our place. The answer is most definitely yes. Don’t worry, it’s a good thing! The most simple answer to the question of how to prune Chinese elm bonsai trees is to let each shoot grow to a couple of inches and then to prune back to the first four leaves. You’ll notice that they start off quite small and get progressively bigger as the new shoot grows.

You are usually aiming to maintain the existing shape, IE a triangle shape with a dome crown. anything that breaks this silhouette can be removed. Plus, any shoots that grow downwards can be removed. Trees in nature don’t tend to do that.

You want your Chinese Elm bonsai tree to get bigger and better over time. So how can this happen? I always say that it won’t magically expand or rise over time like a Yorkshire Pudding does. Instead, the pruning is like topiary – you carefully prune the tree allowing bits of growth to continue in the way that you want it to.

The aim of the game is often to increase the twiggyness of the bonsai tree, rather than the height. Think about it – one cut shoot generally leads to two smaller side shoots, which when cut lead to four smaller shoots.

Feeding your Chinese Elm Bonsai Tree

Feeding can be done all year round with a tree kept indoors. Use either a low-strength liquid feed or slow slow-release granular feed. If you’ve just received a Chinese Elm and are looking into how to keep it, don’t feed it for the first few weeks. Give it a chance to settle into its new environment before starting to feed.

When grown outdoors, we feed them from spring to autumn.

Repotting your Chinese Elm Bonsai Tree

Chinese Elms grow quickly and should be regularly repotted. Very small bonsai will want repotting for two or three years to keep them in the best of health. Here is some helpful advice on how to do this.

Slightly larger Chinese Elms will probably be repotted every three years. Let’s define slightly larger as bonsai that you would need two hands to pick up. Perhaps less than this for very large ones.

Problems with Chinese Elm Bonsai Trees

If you are reading this page, there is a strong possibility that you already have a Chinese Elm bonsai tree and are having problems. Let’s look at some of the most common health problems now.

Yellow leaves on a Chinese Elm Bonsai Tree

This is the big one! It’s the main question that we get.

“Help, I’ve got this Chinese Elm and all of the leaves are going yellow and falling off!”

Me: “How long have you had it? Where are you keeping it?”

“I’ve just got it, It’s in the house.”

Okay, so it works like this – as we said earlier, Chinese Elms are not fully evergreen, nor are they fully deciduous. Most, if not all, bonsai sellers grow their Elms either outdoors or in greenhouses and polytunnels. In these locations, the light is very bright and the air is humid from all the water going everywhere when they water, usually with hosepipes. It is usually a very good, if not perfect growing environment – bright, humid and cool. Your house is not like this. For one thing, your house is dark. Even a windowsill is much darker than its previous location. The drop in light levels affects the tree. It reacts to the drop in light. If it’s winter when you’re reading this, some of the trees outside have no leaves in the darker months of the year. Your Elm thinks winter has well and truly arrived.

As we said earlier, it isn’t fully deciduous though, so it does not mean that it will be without leaves for months. It normally takes about a month to start growing again. Small green buds at first which burst into new leaves. Remember also that it is hot in your house. Confusing for a tree – it’s got dark but warmer, is it winter?! The answer is that it’s an adjustment process that the tree has to go through. It has to adapt the the new location. It isn’t easy for it either. Panicking, people sometimes think it’s the roots and try to repot them, further affecting the tree at this stage. They also often pour water on the tree constantly until the roots have rotted away. Sometimes, they think the tree is cold. Someone told me once that they put the tree in the airing cupboard because they thought it looked cold. Dry, artificial heat from radiators is deadly to them.

So what to do if this is happening? Get the location right – a bright location, away from radiators Not too much water but not too little either.

Remember that outdoors, nature can provide these conditions with little fuss. This is one of the reasons why we try to encourage people to grow bonsai trees outdoors if at all possible. It’s so much easier.

Little Flies all over your Chinese Elm Bonsai Tree

If your Chinese Elm bonsai tree has little white or green flies on it, don’t worry. It only takes one little greenfly to wander over to the tree and it’s found a safe home away from predators. These flies don’t need a partner to produce babies. A single one can cause an infestation. How to get rid of them? You can use any method that gets rid of them from other plants. Insecticide sprays such as Provardo or Roseclear work fine. There are also numerous more natural remedies, which I won’t go into here, but are easily found with further internet research.

Long, leggy and weak growth on your Chinese Elm Bonsai Tree

It’s location again! A tree going in a dark location doesn’t know that it’s in your house. The tree thinks it’s in a wood with larger trees above it, stealing the light. The tree’s solution is to grow long shoots, searching for more light. Warm indoor air also encourages leggy growth. I use the rhubarb example at this point sometimes. You can force rhubarb to grow by putting a black bin bag over it. It makes the rhubarb grow long shoots – more for crumble and fewer leaves. This is happening to your tree. Chinese Elms that grow outdoors tend to have tight growth and nice small leaves. Chinese Elms grown indoors tend to have larger leaves (to hoover up more sunlight) and longer, leggier shoots (to get to the light.)

Weak or no growth on your Chinese Elm Bonsai Trees

Life takes its toll on bonsai trees kept indoors. It’s like if you have some, though not quite enough food. You’ll be ok for a while but eventually, you’ll become weak. You’ll look fine for a bit but after too long, it will start to show. It tends to be after a year or more.

The solution is some time outside in the sun and fresh air. When I say some time outside, please remember that trees live at a different pace to us. I mean months outside, not a few days.

Is my Chinese Elm Bonsai Tree dead?

It’s not easy to keep bonsai trees indoors, due to everything we have been talking about. If your tree has no leaves leaf at all, you can check to see if it is still alive:

Scratch the bark in a few places on the branches. You’re looking for the green cambium layer, which is just underneath the bark. if the tree is still alive, this will be a nice green colour, if it’s brown, that part of the tree has died. Quite often it is still green. If so, Chinese Elms bud from very old wood really well. If that part has died, it should be cut off.

If it does look sick, time outdoors is generally the best thing for it.

 

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