Bonsai Tree Care
by Erik A. Olsen Copyright © 2004
For Bonsai, every season brings a new type of care, as you will see
from the following information. Keep in mind by maintaining up your
bonsai tree care
regimen regularly, your bonsai will continue (or start!) to flourish.
If you live in a region that experiences hard freezes during the
winter, then some species of Bonsai will require extra protection from
the elements. This would include Bougainvillea, Elephant’s Food, Ficus,
Lantana, and Natal Plum and so on. The best option would be to move
the Bonsai close to the house or under a deck or porch prior to the
Place each of them on a table, bench, blocks, or something else, as a
way of elevating it. Next, take a piece of newspaper and cover the
pots. To make sure the newspaper does not blow off, use clothespins or
some other type of anchor. This way, you will eliminate damaging,
vertical drafts. Keep in mind that you do not want to use plastic for
If you have a garage, crawl space, or some other place that is not
heated, that too would work. In this case, you would still place the
newspaper on top of each pot. If your Bonsai does experience damage
from frost, wait to trim it until you begin to see new frost.
Additionally, you want to reduce the amount of watering you give the
Bonsai during the colder months. Typically, you would coordinate your
watering with the current dew point so if you generally water your
Bonsai once every two weeks in the winter but the dew point is
exceptionally low for several days, then you might want to water more
often, just during that time.
It is important for your Bonsai Tree Care that it not be fertilized in the winter.
Instead, you want to wait until you see the beginning of buds.
When roots and stems freeze, there is both chemical and physical
change. First, it is important to understand the three phases of
1. Water freezing in the Bonsai’s soil
2. Inter-cellular water freezing in the Bonsai’s tissue
3. Intra-cellular water freezing in the Bonsai’s tissue
Frozen Water in the Soil
Typically, this occurs when the water in the soil when the temperature
of the three phases is the highest. In nature, water rarely freezes at
a temperature of 32 degrees. However, in soil when ice forms, small
particles are left that solute. In other words, the soil is not
actually frozen, but the ice crystals in the soil.
While some people will tell you that freezing does tremendous damage
to Bonsai, the truth is that the cells of the plant or tree are quite
rigid and used to this type of pressure. Considering that the plants
and trees generally used for Bonsai have been around for more than
1,000 years, it should provide you with some reassurance that your
Bonsai will not die.
Now, if the roots are frozen for long periods and at extremely low
temperatures, it is possible that some damage could occur. If you were
worried about this, remember that plants to have built in mechanisms
that keep them from freezing completely.
Plants have another natural mechanism in which they expulse water from
the cell protoplasm, which is located in the inter-cellular spaces.
What happens is that changes in the cell membranes allow water to
leave the cell, and instead, go into the spaces. Therefore, the water
that does freeze is within the space and not the actual cell.
Finally, when freezing occurs in the intra-cellular portion of the
plant, the cells will die since they freeze. You would typically see
few branches the following spring from this happening. The plants and
trees however do have a built in mechanism referred to as, “Supercooling.”
With this, the sap will stay at liquid temperature so it does not
Each of the three stages has its own freezing point, as shown below:
1. 32 to 23 degrees F
2. 23 to 14 degrees F
3. -4 to -40 degrees F
Keep in mind that the root systems of plants do not necessarily go
through the same level of hardening. For this reason, you will see
that some trees have their roots underground where they are not
subjected to rigid temperatures and other trees have their roots above
When a tree is taken from the ground and then placed in a pot to be
trained as a Bonsai, you need to remember that depending on the type
of plant or tree, you could be subjecting the root system to
temperatures and an environment that it has never experienced. When
this happens, the tree could die.
For this reason, it is crucial for proper bonsai tree care that
it be protected during the in
wintertime, especially in the first few years of change. The best way
to provide protection is to place the Bonsai in the ground outdoors
during the winter so that it is in its natural protected state, or if
you do put it in a pot, add mulch. As long as the roots are not
exposed to killing temperatures, it should thrive. However, if the
plant or tree does die, do not be overly surprised.
Another problem relating to frozen soil is that while typically this
is not a problem for the Bonsai, there are exceptions. First, if the
temperature of the above ground tissues should rise dramatically where
the soil water stays frozen, then transpiration of the water might
occur from the shoots.
As the Bonsai grower, you can help avoid the problem by creating some
type of windbreak for the tree. Excellent options include using a
greenhouse or coldframe. Even if you have an area in the garage or on
a porch or deck, that too would work. If the Bonsai is outdoors,
again, make sure it has plenty of mulch built up around the base.
To keep this all straight, you can refer to this guide any time you
· If the Bonsai will be created from a temperate plant, it will go
dormant in the fall. At that time, shorter days and falling
temperatures will be a consideration. When exposed to shorter days and
lower temperatures, any frost will encourage the plant to begin cold
hardening, as a way of sustaining itself through the cold months.
· Bonsai from temperate plants will need to have a time of “chilling”.
This will help break the dormant time, thus starting re-growth.
Typically, this time is considered anywhere from250 to 1,000 hours
with temperatures ranging from 34 to 50 degrees F.
· Any buds, leaves, or shoots above ground from temperate plants that
have gone through the cold hardening phase can generally handle very
· The Bonsai roots from most temperate plants will not cold harden,
which you would find in above ground plants. Therefore, they are very
susceptible to low temperatures, becoming damaged quite easily.
· Freezing soil it not always a threat to your Bonsai. However, if the
Bonsai has frozen soil and then exposed to long periods of shoots
being in the cold or drying winds, you could have damage or dying
· Always allow your Bonsai to go into its dormant state and cold
harden properly. For instance, exposure to the first fall frosts is
· Keep your Bonsai in an enclosure or pot that is well watered and
where temperatures can be controlled all winter long.
· Any plants that are removed from the protected area during cold
temperatures could cause the plant/tree to die
Spring is a busy time for Bonsai in that you will be working with
re-growth, new growth, potting, and styling. In addition to this, you
may have some potted Bonsai that have been in their pot for two years,
meaning these too need to be pruned, shaped, and repotted.
However, to change the appearance of your Bonsai, this is the time to
consider something different, which could be done by repositioning the
tree in its current pot. If you prefer, you can completely change the
style, whichever you prefer. When you begin to see new leaf buds, you
want to pot or repot the Bonsai to ensure they have adequate internal
reserves to keep growing while the feeder roots are absorbing
nutrients. However, if you do not provide the Bonsai with root
pruning, then these feeder roots will become active quicker.
When working on your Bonsai during the spring, you should find a shady
place out of the wind, and preferably with a 30-degree dew point. To
ensure the root balls stays moist, you also want to keep a spray
bottle on hand. During the spring, you will be cutting various parts
of the tree so you want to make sure you produce clean cuts by having
If the plant is young, then it will require more pruning of the roots.
To accomplish this, the tap should be removed along with the larger
roots, using concave cutters. Take care not to cut anything except the
roots. Spring is the time of the year when you will fertilize the
Bonsai, using components of Nitrogen/Phosphorus/Potassium. The
Nitrogen will benefit the leaves and stems, the Phosphorus the roots,
and the potassium, the flowers.
While you could use non-organic fertilizer, your Bonsai will actually
do much better with organic matter. For your repotting soil, the tree
would do well with a little application of slow-release, solid
fertilizer that contains micronutrients. Now is the time to examine
the growth of the roots. If they have not grown as much as you would
like, then change the soil to one that is coarser and that drains
Additionally, reduce the amount of nitrogen, while increasing the
level of phosphate. Finally, the roots should be left alone for a
minimum of two years. Make sure the tree is out of direct sun and
wind, for at least one week. Then very slowly, you will introduce it
to these elements so it can adjust naturally.
Although you will still water on a regular basis, initially reduce the
amount you give the tree. This transitional time will help your Bonsai
look better. Then after two to three weeks, you will add organic
fertilizer. If you have a Pine or Juniper, you would also want to add
fish emulsion once a week. Then any flowers should be cut off at the
end of their blooming period so the Bonsai will look stunning the next
In most cases, you would not want the trunk or branches to become too
bulky. To make sure this does not happen, any new side buds and
branches should be maintained at a shorter length. The best guideline
is that active buds should be limited to pairs, keeping no more than
two buds per branch. Going back to Pines and Junipers, these may
require weekly trims to help ramifying growth.
Summertime always presents unique challenges for Bonsai but with the
proper information and tools, you can maintain your plant’s health.
As an example, the following tips will help your Bonsai not just
survive but thrive during the summer months:
· Make sure you are using fresh, healthy soil
· Every week, rotate your Bonsai about one-quarter turn so that the
entire plant receives an equal amount of sun and fresh air
· Keep the Bonsai well trimmed, specifically species that tend to get
out of control such as elms and junipers
· Pay attention to the water levels along with the retention for the
type of soil you are using
· After noon, make sure your Bonsai has an overhead shade cloth
· Place your Bonsai on slatted workbenches on the lawn or gravel and
then in the morning, soak the ground. Then, occasionally, provide the
Bonsai a good misting.
· While setting your Bonsai near a pond or swimming pool is fine, be
very careful about placing them in pans of water in that the sun can
reflect and cause problems
· Set your Bonsai in groupings but make sure none of them are touching
· Protect your Bonsai from the western or hot afternoon sun
· Grow your Bonsai in a growing bed as opposed to pots
· For maples and other thin-edged leaf bearing Bonsai, water them with
reverse osmosis or distilled water
· Fertilize the Bonsai regularly using half the normal strength
· If you notice any wilted leaves, reduce the amount of water and
place the Bonsai in the sun
· Remember that only your larger Bonsai should be placed in full sun.
For instance, plants such as elephant food, bougainvillea, Texas
ebony, junipers, and dwarf myrtle would do fine in full sun but any
Bonsai that are root-pruned or ones you have recently repotted.
· During the late summer and early fall months, be sure you use
fertilizer that is high in phosphate. A great blend would be 10-60-10,
which helps the buds build a reserve for the following spring.
For the fall, you need to be careful with your Bonsai, not allowing
them to get out of control. Many times, species such as elms,
junipers, and pomegranates grow very fast in the fall so you will need
to keep new growth pinched back.
One of the most important things to remember during the fall is that
you need to monitor your water retention for the soil mix very
carefully. If you are not cautious with this, you will easily over
water, killing or severely damaging the plant.
Giving your Bonsai a fertilizer high in phosphate, using a blend of
10-60-10 is beneficial. What happens is that this type of blend will
help the buds maintain a reserve so that in the spring, they can
flourish. Additionally, for your juniper and pine Bonsai, you probably
want to wire them during the fall, constantly checking them for fast
growth that could cause scarring.