How To Prune Flame Tree Bonsai: A Care Guide

Bonsai are maintained through several processes, such as watering, feeding, repotting, pruning and wiring. This helps them keep their tidy and compact appearance while helping them to thrive as a tree.

The flame tree is called royal poinciana, flamboyant tree or fire ree. It’s a tropical species belonging to the legume family, and its flowers are large red or gold blooms that appear in spring and summer months.

In this article, I’ll detail how you can keep a flame tree bonsai alive and how to prune it!

Watering

Watering is the most critical part of keeping bonsai or any plant alive. Water is a vital substance in photosynthesis, which gives your tree the energy to function and live.

If you don’t water your tree enough, it can kill it quickly, depending on the temperature and environment.

Flame trees, specifically, need quite a lot of water, especially in summer. It can tolerate short periods of drought. However, you should always give it water if you can.

In winter, flame trees and many other trees will need less water than in summer. You should also avoid using ‘hard’ water, which is too alkaline, as flame trees prefer a pH of 4.5 – 7.5.

Underwatering

Underwatering is when your tree is not receiving enough water. Some symptoms of underwatering include the browning or yellowing of leaves and the dropping of leaves.

To avoid underwatering, I always check the moisture of the soil of my bonsai trees by poking my finger an inch deep into the soil. This helps me understand the soil’s moisture and if it needs watering.

You can also do this with a wooden chopstick if you prefer to keep your hands clean!

Ideally, the soil should be moist, not wet. You should only water when it’s slightly starting to dry out. However, you should never let it fully dry out as this will kill the tree very quickly.

Overwatering

Another vital part of keeping your bonsai tree alive is not overwatering it! Overwatering may take slightly longer to kill your bonsai, but it’s still something you need to look out for.

If you provide your tree with too much water, this can kill it. It will starve the roots of oxygen, causing them to rot and no longer function.

Some common symptoms of overwatering include the browning and yellowing of leaves, leaf drop and roots, which are miscoloured and rotten, usually accompanied by a terrible smell.

To avoid overwatering, the soil should not be constantly wet. If you’re afraid you have been overwatering your tree, you should tip the pot on its side to drain as much water as possible.

Another good way of preventing overwatering is by potting your tree in free-draining soil, such as Akadama or pumice. These soils are specialist soils from Japan and are very commonly used in bonsai. Soil such as compost is too heavy and will hold too much water, which can rot the roots if you’re not careful.

However, even if you have overwatered your tree, you still need to water it regularly. Never let the soil completely dry out, as this will desiccate the roots and cause the tree to die.

Light

Again, one of the most significant factors in keeping any plant alive is giving it the correct amount of light. It’s essential for photosynthesis.

In particular, flame trees like to be in a sunny place outside in the growing season. They can handle full sun and tolerate partial shade to full shade.

Temperature and Overwintering

An essential part of keeping your bonsai tree alive (especially in the winter) is ensuring it’s in an environment with the right temperature.

Some trees cannot handle very low temperatures, while some can. For example, maples can withstand temperatures as low as -10 degrees. However, trees like flame trees cannot handle such low temperatures.

Flame trees prefer to stay above 10 degrees outside in the growing season and shouldn’t be subjected to drastic temperature drops.

Outside the growing season, the tree should be placed somewhere, such as a greenhouse or in a house, with temperatures between 10C and 20C.

Before you overwinter your trees, I recommend spraying them with a fungicide before you put them into storage. This helps kill off any diseases on the tree which might flare up in spring and cause damage to your tree, holding back growth.

Wiring

One of the most commonly used practices in bonsai is wiring. It helps to form and keep the appearance of a bonsai tree, providing stunning images.

Wiring can be done at pretty much any time of the year. However, in winter, you can see the structure much better on deciduous trees, helping you make better decisions and get into the tree better.

Wiring is usually done with either anodised aluminium or copper wire. These both have their advantages and disadvantages.

When applying wire, you should use the wire at a 45-degree angle. This helps to conserve wire and get the best out of bending the tree. Never cross wire either, as this can restrict water movement in the tree and lead to the tree ‘throwing’ branches, which means it kills them.

You should also check every 2-3 months to ensure the wire isn’t biting into the bark of the part you’re wiring. Otherwise, this will leave nasty wire scars on it for quite a while. If you end up with wire scars, make sure when applying wire, you wire inside of those scars to prevent any further scars from being left on the tree.

To remove the wire from a tree, you should not uncoil it with your hands. Instead, opt for a wire cutter. Cut the wire at the same point along the branch, and it should come off easily. If it doesn’t, you can uncoil it slightly with your hands, but be very careful not to break the branch or strip the bark off.

However, before you start wiring anything, you should consider why you’re doing it. If you don’t have a clear idea of why you are or what you want the tree to look like, I recommend holding off on wiring until you have an idea.

Wiring shouldn’t be done pointlessly; you should have an end goal in mind.

Aluminium Wire

Aluminium wire is typically quite a bit cheaper than copper wire, which can be suitable for someone just starting the hobby.

Compared to copper wire, aluminium wire is also easier to work with. It’s a lot less stiff and can be used on most trees. However, it may not be as good for conifers such as junipers or pines.

Copper Wire

Copper wire is usually a bit more on the expensive side compared to aluminium wire. However, it can be worth it when working on specific trees.

Copper wire is much harder to work with than aluminium wire, as it becomes stiff and less malleable when you bend it. However, this can be a good thing on trees such as conifers as they need a very strong wire to keep their branches in place over a long period.

Fertilising

Fertilising your tree is an essential part of growing bonsai. If you think about it, you’ve taken a tree which usually develops in the wild with a lot of access to open soil and nutrients, and put it into a small pot where the only things keeping it alive are you and the sun.

Bonsai cannot get nutrients from anywhere else but you; you need to give it fertiliser every ten days in the growing season if you want to push a lot of growth.

With flame trees, you should apply liquid fertiliser every week in the growing season or an organic fertiliser every four weeks.

There are many different fertilisers you can use. However, the most popular brands bonsai enthusiasts use are Naruko and Biogold. These are special Japanese fertilisers, but you can still use any ordinary garden centre fertiliser as long as it’s balanced.

NPK (Nitrogen, Phosphorous and Potassium) ratios are essential in understanding fertilisers. Nitrogen helps to drive growth in the tree, phosphorous encourages and supports the formation of fruit and flower buds, and potassium allows for processes such as water movement in the tree.

In the growing season, I like using a fertiliser high in nitrogen to push growth. However, I like to tone it down in autumn to a minor nitrogen concentration and increase phosphorous and potassium to help in overwintering.

Using a fertiliser with too much nitrogen in autumn can encourage growth, which the frost can potentially kill off if it hasn’t hardened off properly.

Over Fertilising

Even though fertilising is good for your tree, it can still be harmful if you give it too much. This can burn its roots and prevent them from taking up water, killing your tree.

To prevent over-fertilising, you should only apply fertiliser every 7-10 days in the growing season. Don’t fertilise outside of the growing season if the tree has no leaves, as this will have no effect, and it’s a waste of fertiliser.

If you have over-fertilised your tree, drain it as much as possible. Submerge the pot for a while, which should help to remove as much fertiliser as possible. Hold off on fertilising the tree until it has fully recovered.

If you love propagating plants like me, you shouldn’t fertilise very young cuttings. This can burn the roots very quickly compared to older trees, leading to the cutting dying.

Pests and Diseases

Pests and diseases are the one thing to absolutely hate finding on your trees. It can affect every species of tree, even flame trees.

Some common pests include aphids, vine weevils, spider mites, and caterpillars. Pests such as aphids are most easily identifiable due to the excretion of ‘honeydew’, which is sticky and shiny. They like to bunch together on leaves. Spider mites look like tiny spiders – terrifying!

Some common diseases include black spot, rust, powdery mildew, canker disease, leaf spot, and chlorosis.

To treat pests, I usually use an organic pesticide, such as a combination of dish soap and water. This is a lot less harmful than chemical pesticides. Chemical pesticides can kill helpful insects in the garden, such as bees, ladybirds and butterflies.

Different diseases will need other treatments – however, I always opt for a chemical fungicide. Even though I don’t support the use of chemical pesticides, I do use a chemical fungicide. I like to always be on the safe side with disease, as I’ve found that organic solutions such as milk and water don’t work.

Some diseases, such as chlorosis, can be treated much easier, though; it’s usually caused by nutrient deficiencies or high alkalinity in the soil. Therefore, I like to use low concentrations of white vinegar once a month to break up hard water.

Repotting

An integral phase in bonsai care is repotting, which is typically carried out every 2-3 years for younger trees. It stands out as one of the more intimidating tasks, and finding the best time when to plant a bonsai tree is crucial for its successful growth.

When people receive their first bonsai, they are usually eager to repot it as soon as possible. If it’s not the right time (usually spring), this is a bad thing to do as it will put unnecessary stress on the tree.

Flame trees should be repotted usually every other year with a well-draining soil mix such as Akadama and pumice.A flame tree can handle root-pruning, and you should take off dead roots and any roots that circle at the bottom of the tree. Due to their acidity preference, you can add some acidic soil, such as Kanuma, into the mix.

Trees should only be repotted for a few reasons, such as being very root-bound, lacking water permeability or something stuck in the root ball, causing damage to the tree.

If you find your tree is becoming root-bound yearly, I recommend going up a pot size to prevent this. This usually occurs on more vigorous trees.

How To Repot A Tree

To repot your tree, you should loosen the tree out of the pot slightly. You can do this by tapping and pressing on the bottom of the pot if it’s potted in a weaker material pot, such as plastic. If it’s not, you can work the edges of the pot with something like a sickle or chopstick to loosen the roots. Once reduced, you should be able to push it out.

After this, I will typically loosen the roots by taking some soil off the edges and bottom of the root mass. Depending on the size of the tree, you should adjust how much you take off. For example, if it’s a very young tree, you should only take a small amount off. However, if it’s an established tree like 5-6 years old, you can get away with taking quite a bit more root off, as the roots are a lot more likely to be less sensitive. Some people like to wash the roots by submerging the tree in water, removing any soil around the roots.

I don’t use this method, as I don’t believe in England’s unstable climate enough to trust that the roots will be able to cope with this level of maintenance and cleaning. On my more significant trees, I like to utilise wedge cuts. Think of it like a slice of cake – you cut from the middle out to the edges, with a sector. This is useful for repotting, as you remove old soil and replace it with new soil each time you repot the tree, making sure there’s no old soil which won’t be as helpful or valuable as new, fresh soil.

Ideally, it would be best to prepare somewhere to repot your tree. I like to use a plant bench. However, you can do it anywhere you’re prepared to clean. Repotting can get messy, so consider some gloves and a hose.

Soil Mixes

I prepare my soil mixes before spring, ensuring it’s ready for all my trees to be repotted. I like to use mostly Akadama with some pumice mixed in for most of my trees. Many of my younger plants are azaleas, so my acidic soil mix is 40/40/20 Kanuma, sphagnum moss and Akadama.

After preparing somewhere to repot the tree, you should also prepare the new pot that the tree is going in. Otherwise, you might have to interrupt your repotting process! Remember – if it’s a seedling or a cutting, it’ll do much better in an ordinary pot than a bonsai pot. Bonsai pots are meant for established and developed trees to show them off, while younger material should be trained first and not restricted in growth to a smaller pot.

To prepare the pot, you should make sure that it’s clean. After this, you should add mesh to the drainage holes, tying them with some wire, usually aluminium wire, as copper wire is not used for this. This prevents any loose soil from falling out, but this can’t be helped on some bigger pots, and it may not be cost-effective to use this method.

I will also use tie-in wires which will help to keep the root mass in place while it grows into the soil, preventing it from falling out of the pot if, for example, it got knocked over by the wind or by a pet.

The wire holding the mesh in can be a relatively small gauge, but the tie-in wires should be a high gauge to ensure that it properly secures the tree in the pot.

After this, you should put a mound of soil in the middle of the pot and wiggle and smush the tree onto the mound. This will ensure the soil gets into the root ball, ensuring there are no air pockets underneath the trunk, ensuring that it has a lot of soil to grow into before it’s next repotted. After this, I then fill the tree with more soil.

You must firm the soil into place with something like a chopstick, preventing any air pockets from forming. You should be thorough and ensure that no more soil can be pushed down. Otherwise, this could be bad for the tree down the line and mean that you might have to repot more frequently.

After the tree is fully repotted, I like to give it a thorough watering to ensure it can deal with the stress I just put it through. In regards to aftercare, I’ll place it in partial shade for a few weeks and ensure it’s not being overwatered or underwatered, which is crucial for a newly repotted tree to survive. It would help if you also watched out for any late spring frosts, which can damage both the roots and the buds, particularly on flowering trees such as azaleas. In particular, this can kill a lot of seedlings, so whenever frost is forecasted, I make sure to put them in storage for the night.

Pruning

Pruning is a vital part of developing a bonsai. If we didn’t prune, our trees would be unkempt and not as appealing as shown!

Surprisingly, pruning is also very good for bonsai. It helps to encourage growth in the trees, and pruning dead branches can improve the tree’s health.

Some bonsai prefer being pruned in later months, such as November – January, specifically maples. This is because maples will bleed sap earlier in the year, which can kill the tree if it’s not treated properly.

How to prune flame tree bonsai

There are two types of pruning done – maintenance and structural. Maintenance is usually light pruning given to keep the shape of a tree, while structural pruning is where larger branches are removed, which can normally give an instant effect.

In early spring, you should prune your flame tree bonsai. A flame tree already quite developed and established can handle being trimmed consistently to control the vigorous growth and develop further ramification.

In winter, flame tree bonsai should have any unwanted shoots pruned.

Frequently Asked Questions (FAQ)