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The Study Group


A reminder for new study group members and seasoned study group members.


The intended purpose of the study group is for us all to learn more about bonsai and take home skills that we can apply to our own bonsai. I am here to help guide you (not do it for you) in the process of learning bonsai and exploring the possibilities of your material.  You have a voice in the process too!  I will let you know my thoughts but I’d like to hear your thoughts and plans as well.  The only expectations I have of the participants is an open mind and an eagerness to learn.  Give me that and I will teach you everything I know!


All in all, at the end of the day, we should all be having FUN doing Bonsai.

Trees to Work on This Month

The month of February is very much a continuation of January.  Re-potting, Style or Grafting concepts apply at this time of year.  So if you were overwhelmed with Bonsai work in January, you can now relax because you have the whole month of February to catch up! This month we will continue talking about other concepts related to re-potting and some pre-Spring maintenance you can do with your Bonsai before Spring arrives.

Pot Temperature

Different trees require different temperature ranges for ideal root growth. If you can get the soil of your Bonsai to stay within the ideal temperature ranges, the roots will grow faster and in turn, the foliage will grow faster.  If the soil temperature moves out of the ideal ranges, then the roots slow down and the foliage will slow down as well.  Ideal growth ranges are different for each type of tree so you have to consider what's ideal for your trees.  For the most part, conifers tend to have a narrower growth range of 70-90 F whereas deciduous trees have a wider range of 50-90 F. These figures are from my own observations.

When it comes to re-potting your bonsai, you now have to consider all the factors that will affect the temperature of your soil. These factors include:

1. Pot size (Small pots heat up faster whereas larger pots heat up slower).

2. Clay vs. Glazed vs. Plastic (Clay and plastic pots tend to heat up faster).

3. Sun Exposure and for how long.

4. Wet soil mixes (Soils that hold water longer tends to take longer to heat up).

5. Dry soil mixes (Soils that hold less water and have more air tend to heat up faster).

This write up is not to tell you what is the right thing and wrong things to do in Bonsai but to get you thinking about how the soil temperature will affect the growth of your roots.  How fast do you want the roots of your Bonsai to grow?  Is fastest always what you need? 


An easy way for you to check out the root temperatures for your Bonsai is to get an instant read thermometer and stick it into the soil during different times of the day (Do this during different seasons as well).  Also, check the soil temps closest to edge of the pot and then closer to the trunk of the tree to observe the differences.

Fertilizing and Re-potting

Some people will fertilize their bonsai as they are re-potting.  I personally don't recommend this technique because I like to have more control of the growth of my Bonsai.  Once mixed into the soil, if you want the fertilizing to stop, you now have no way of doing that short of re-potting the tree again.  If you apply fertilizer to the top of the soil, at least you can remove it if you decide you didn't need it after all.

Often I get asked the question, "Should I fertilize my bonsai after re-potting?"  The short answer is, "no," and the long answer, "it depends."  Just ask yourself, "how much do I need this tree to grow right now?"  If you are trying to push the tree and get it really strong, then go ahead and fertilize.  If you don't want the tree to grow too fast but instead, looking for slower stable growth, then don't fertilize till a later time.

Spring Soil Cleaning

If you don't plan to re-pot your Bonsai, you can still clean up the soil.  Throughout the year, fertilizing and watering, the top soil of your Bonsai will become compacted and clogged with debris.  What you can do at this time of year is to scrape off about 1/4 - 1/2 inch of your top soil and apply new soil.  This will allow water to flow easier into the rest of the soil below.

Moss on Trunk

Other things to look for is moss creeping up the trunk of your Bonsai.  For trunks that have bark that you're trying to preserve, moss can grow onto it keeping it so wet that the bark starts to rot.  This can potentially ruin the old characteristics of the trunk is you need to keep the moss growth under control.

The best way to keep moss from growing on the trunk of your Bonsai is to never allow it grow in the first place.  Keep an eye out for moss growth and if you see it start to develop, you can apply a 50/50 mix of water and vinegar and apply it on the moss.  The pH change will cause the moss to brown out and break apart.  After application, try not to water the treated area for maximum effect.

Of course, we can't always catch the moss growth in time and before we know it, it's 1/3 up the trunk.  Generally when this happens, you can still use the vinegar technique to kill the moss, but then the dead moss will still be stuck on the trunk of your Bonsai.  After the moss is dead, you will have to go through and carefully remove the moss with forceps. Do not brush the moss away because it will knock the bark off your Bonsai.  No magic solution or trick here, just careful laborious work.  That's why it's better if we never let the moss develop in the first place.

For other Bonsai that have smooth bark, it's much easier because in their case, you can just brush the moss away. There's no bark to worry about so it makes it nice and easy.


Moss or Algae on Deadwood


Deadwood on your bonsai that is close to the soil tends to stay wet longer than deadwood higher on your bonsai. When deadwood stays wet long enough, moss or algae may start to grow on it. With enough time the wood will start to rot away and change the design of the original deadwood.  All we can do is limit how often we get the deadwood wet and if moss or algae does develop on the deadwood, it's time to bring out the plastic and brass brushes to scrub the buildup off.  Once the moss or algae is off, allow the deadwood to dry and try not to spray it with water when watering the tree itself.  Another thing you can do after the deadwood is dry is to treat it with Lime Sulfur.  This will temporarily protect the wood from water and will need to be reapplied every now and then. Just be aware that Lime Sulfur will turn the deadwood a white color.

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