Monthly Bonsai Care in North Carolina

What follows is information provided by Mr. Howard Kazan, a noted North Carolina bonsai artist and teacher. He has been practicing bonsai for over 30 years. His comments below were originally published in the newsletters of the Triangle Bonsai Society in Raleigh and is used by permission of Mr. Kazan. The reference herein to the 'Triangle Area' is a N.C. region which includes the cities of Raleigh, Durham, and Chapel Hill, which are located about 3 hours north and east of the metro Charlotte area.  The climate will be a little different there... but not much.  If you live in a different climate zone, the suggestions made herein might have to be adjusted.  The Triangle area is slightly colder than Charlotte, but for the most part, the advice Mr. Kazan provides is entirely applicable to Charlotte.

January

The primary goal of January bonsai maintenance is to keep the trees alive throughout the winter. You must allow temperate bonsai to go dormant during the winter, they must not be kept indoors, but they need to be protected outdoors.

You must protect your bonsai from extreme cold and drying winds. This can be done by mulching in the ground up to the bottom branch or by storing in an unheated building or cold frame. Most years in our area, the trees can be kept outside, as long as they are protected from strong winds, and only moved into an unheated building when temperatures drop below 30 degrees.

The trees should not dry out, but they also must not be over-watered. The trees are not going to use much water this time of year and root rot can be a problem with too much water. Do not fertilize this time of year.

Tropical and semi-tropical bonsai need more care and higher temperatures than temperate bonsai. They need to be kept indoors, with adequate light and humidity. If you do fertilize, use a weak solution.

Febuary

Basic care of bonsai should be the same as in January. This is a good time for planning. Read books, and look at photographs; study your trees, and try to imagine what you want to accomplish. The truth is that most of us lack the gift of "inspirational pruning;" we need to plan carefully. To paraphrase words from another craft, "think twice, cut once." It is a good idea to "make a decision" about a particular tree, taking notes or tagging the limbs you decide to cut. Then put it all away, and come back a few weeks later to look at the tree all over again. See if you reach the same decision a second time.

As Kazan reminded us in his lecture, this is also a good time to go out and look at trees in nature, in 

particular, deciduous species that now show the lines of their trunk and limbs. 

 

March

March begins the busiest time of the year, when you can do creative work along with the necessary tasks.
 

Repotting. Any healthy deciduous tree that needs to be repotted, can be repotted if there are early signs of root or bud movement. Buds should be just beginning to swell, once they have opened it is generally too late to root prune or repot. Continue to keep newly repotted trees away from hard frosts and drying winds; optimum recovery will occur if they are kept above 45 degrees. Until the buds have opened the trees have no need of light, so they can be kept inside an unheated building. Once the buds open, trees must be placed outside, but move them into full sun gradually so that they are not fully exposed until four weeks after repotting. Do not fertilize after root pruning until the tree has a chance to grow new feeder roots (again, approximately four weeks). Use ½ the recommended concentration as strong fertilizer can damage the new roots and even kill the tree. Be patient. Root growth will be promoted if you allow the soil to get somewhat dry between wateringsWhen the soil starts to dry, the tree responds by growing new feeder roots. Be especially careful not to allow newly repotted trees to become too wet. Place them under a shelter during rainy spells if necessary and tip after watering.

Pruning. Because you should always prune to a side shoot or bud that is pointing in the direction you want new growth, wait to prune deciduous trees until the buds begin to show signs of activity. This will ensure that the bud of interest is alive. If you are repotting, pruning should be done at the same time.

Wiring. If possible, start wiring deciduous trees before the buds swell. Once they swell, they are easily dislodged and extra care should be taken. Branches will swell rapidly during the spring, wire should be checked often to prevent damage to the bark. If the wire is too tight, but the branch has not set, the old wire should be removed, and the branch rewired. Wrapping the wire in florist tape helps prevent damage to delicate bark.

General. Inspect the soil surface of trees which are not being repotted this year. Remove any dead or disfigured moss and any compacted, crusty soil. Replace if with fresh soil. Check plants for disease and insect pests and treat if necessary. The wiring and shaping of the trees is an ongoing process and should be attended to on a regular basis.

Conifers. Most junipers, pines, etc., follow the same schedule as the deciduous trees, only several weeks later in the spring. Lift plants from their pots and inspect the root system. Do not repot until new growth (a short segment of very light color) is evident in a few root tips on the surface of the root ball.

April

Pruning, repotting and care. Most plants are breaking bud by now. Deciduous trees may be repotted up to the time that the buds begin to open. Junipers are hardy and may be repotted into April. Flowering plants are usually repotted after they have finished flowering. If the tree is weak, or you want as much growth as possible, it is best not to let the tree bloom as this uses a great deal of energy. Remove the flower buds as soon as they can be removed.

Be cautious if repotting from nursery stock. Remove rootage carefully, usually about 1/3 to ½ to maintain the health of the plant. The process may be continued over the next year or two before placing in a bonsai container.

On finished bonsai, pinch and trim new growth as it develops to maintain the original design and profile. Take special care with older bonsai for they do not respond well to drastic pruning.

For trees in training, consider letting new growth elongate to thicken trunk and branches prior to pruning. Remember to always keep the health to the plant in mind.

Check daily plants that are wired. Branches will thicken rapidly for the next month or so and the wire can easily cut into and disfigure the bark. Check small branches wired last month—they may already be set in position. Remove wire as needed by cutting with wire cutters along the curves, it is not worth breaking a branch to try to save some wire by unwinding it. If the branch is not set but the wire has become too tight, remove the old wire and rewire the branch, winding in the opposite direction.

Check plants daily. Water when the top 1/8 to ½ inch of soil it dry(depending on the depth of the container). Do not overwater.

Pests will become active the time of year. Watch for aphids and red spider mites in particular. If you use a pesticide to control pests, follow the label directions.

Fertilizer. Applications may be started this month. Remember not to fertilize newly repotted plants for several weeks, and then start with a weak solution, One low in nitrogen is best to start off with. For plants in training use a balanced fertilizer, such as 10:10:10, to encourage rapid growth. Use a weak solution often, instead of a strong one once in a while.

The main nutrients in fertilizer are nitrogen(N), phosphorus (P), and potassium (K). These are listed on containers as NPK followed by numbers such as 10:10:10, these numbers denote their ratio. The higher the numbers, the stronger the fertilizer. For bonsai it is best to stick with weaker concentrations. But what do each of these elements actually do?

Nitrogen. This is responsible for leaf and stem growth and can enrich the color of the foliage. Without any nitrogen a plant would only produce a few stunted leaves and growth would be poor. The plant’s health would quickly deteriorate because it would not be able to carry out the process of photosynthesis efficiently. Too much nitrogen and the growth will be too vigorous. Large leaves will be borne on long, sappy shoots which will soon outgrow their own strength, and the tree will be prone to disease.

Phosphorus. This is primarily responsible for root growth. It also encourages thick, sturdy trunks, helps to strengthen the plant against disease and frosts, and promotes backbudding. An excess may result in poor foliage growth and color.

Potassium. Potassium, or potash, is responsible for encouraging flowers and fruit as well as hardening off late growth before the winter. If left out of its diet, a plant will fail to flower, or if it does then the blooms will be of poor quality and the fruit will not set. Potassium also helps to build up the plant’s resistance to disease. 

May

Watering . With full foliage and warm weather, trees are now using much more water. In theory, provided your bonsai is growing in a free-draining soil, it should not be possible to over water. But many of us, especially beginners, manage to do just that. Over watering eliminates the air contained in the spaces between the soil particles and deprives roots of the oxygen they need. It also creates the conditions favored by various root-rotting fungi. The symptoms of decaying roots (yellowing foliage and lack of new growth) are not usually apparent until the damage has already been done.

Many trees will require watering daily, but avoid watering a tree that doesn't really need it. Wind can dry the soil's surface, while deeper in the pot it may still be quite wet. If in doubt check by scraping away the surface in a couple of places and adjust the frequency of watering accordingly.

Generally the best method is to water the surface of the soil evenly, using a fine spray, until the water drains out of the drainage holes. Wait a few minutes and repeat. This ensures a thorough wetting of the soil and should be sufficient for one day during the height of summer.

The best time to water is in early evening. This gives the tree plenty of time to have a good drink before morning. If you water in the morning the tree doesn't have much of a chance to refresh itself before the heat of the day. If you can't avoid watering in the morning do it as early as possible. Another advantage with evening watering is that you can douse the foliage at the same time without the risk of leaf scorch caused by the water droplets acting as miniature magnifying glasses in the sun.

A word of warning. Don't assume that a rain will do the watering for you. A bonsai acts like an umbrella and shelters the pot from light rain. It is worth the time to check for adequate moisture, even in wet weather.

Feeding. This can be a source of much confusion for the novice but the principle is quite simple. There are three ways to apply fertilizer: by placing pellets in or on the soil, by watering it into the soil and by spraying it on the leaves (foliar feeding). Each has its pros and cons and the choice is really based on your own preference.

Fertilizer pellets. Specialist bonsai fertilizer pellets are available from bonsai nurseries. They can be either organic or inorganic. Both types release nutrients slowly, which means that you don't have to worry about feeding for a while. The disadvantage is that you won't be able to adjust the feeding pattern without risking over feeding, which may "burn" the roots.

Soil application. There are a large number of soluble fertilizers available, such as Miracle Grow and Peters. These can be routinely applied once a week or, better yet, at a quarter strength with almost every watering. It is a good idea to change brands every once in a while, in order to provide a balanced diet. The disadvantage with soil application is that the nutrients wash out of the soil quickly, so you have to be diligent in your feeding regime. Also, during prolonged periods of wet weather you may not be able to feed your trees since they may not need any water.

Foliar feeding. Research has shown that a plant can absorb more nutrients through its leaves than through its roots. Many standard soluble fertilizers can be applied in this way as well as via the soil. This technique is particularly useful when your bonsai has root problems or when the soil is constantly wet through heavy rain. Foliar fertilizers are easy to apply provided you don't do so in strong sun, or the leaves may scorch. The only disadvantage is that in warm, windy weather the solution dries on the leaves too quickly and leaves a powdery deposit which is difficult to wash off.

Any of these methods of feeding are suitable for keeping an established tree in good health and vigor, but occasionally you may need to use a special fertilizer in order to encourage to tree to perform in a specific way. Before attempting, you will need to understand how each of the major nutrients affects the tree. Refer to the April Newsletter for this information.

Special feeding programs: Nitrogen (N) should be increased when you want a plant to put on a spurt of rapid growth. This applies to young, developing plants which you want to grow larger before starting to train. If the foliage is dull (not yellow - which indicates a root problem) a little extra nitrogen may improve the color.

A high nitrogen fertilizer should be applied as the tree needs it, not before. So in spring, after growth has started, or once new leaves have emerged following leaf pruning, an application of a high nitrogen fertilizer will replenish the tree's resources.

Phosphorus (P) is especially useful after repotting or when a tree is recovering from a root problem, so a little can be given at such times. In fact, a high phosphorus and potassium fertilizer will aid recovery from many ailments. Increasing the phosphorus content in the diet in late summer and autumn toughens up the tree in readiness for autumn and winter. A pinch of powdered superphosphate on the surface of the soil is an easy method of application.

Potassium (K) should be increased for all flowering and fruiting bonsai. A diluted rose or tomato fertilizer is ideal, as these are specially formulated to increase the flowering and fruiting potential. Potash can also be increased to help weak plants regain strength. Extra potassium given during late summer and autumn will help the tree combat the perils of winter. A little sulphate of potash sprinkled on the soil once a week will do the trick.

Some nurseries sell a specialist soluble fertilizer called "0-10-10" which, as the name implies, is nitrogen free and is ideal for late season fertilizing. When buying fertilizers make sure that they contain trace elements. These are only required in minute amounts, but without them your bonsai will surely suffer.

Wiring. Check wired plants daily. Branches will thicken rapidly for the next month or so and the wire can easily cut into and disfigure the bark. Check small branches wired last month - they may already be set in position. Remove wire as needed by cutting with wire cutters along the curves, it is not worth breaking a branch to try to save some wire by unwinding it. If the branch is not set but the wire has become too tight, remove the old wire and rewire the branch, winding in the opposite direction.

Pests and Diseases. Bonsai should be checked often for signs of pests and diseases. Since bonsai are small and compact, it doesn't take long for a problem to spread over the whole tree. Treat immediately.

June, July and August

Watering. During the hot summer days it is necessary to check bonsai every day to see if they need to be watered. When it is really hot, you will need to check morning and evening. The amount of water needed will depend on the heat, the wind, the amount of foliage on the tree, the type of soil and the depth of the pot. Water the trees thoroughly, making sure that the pot drains easily. Poor drainage promotes root rot.

Generally the best method is to water the surface of the soil evenly, using a fine spray, until the water drains out of the drainage holes. Wait a few minutes and repeat. This ensures a thorough wetting of the soil and should be sufficient for one day during the height of summer. Try to avoid watering a tree that doesn't really need it. Wind can dry the soil's surface, while deeper in the pot it may still be quite wet. If in doubt check by scraping away the surface in a couple of places and adjust the amount of water accordingly. 

A word of warning. Don't assume that the rain will always do the watering for you. A bonsai acts like an umbrella and shelters the pot from light rain. It is worth the time to check for adequate moisture, even in wet weather.

Feeding. Fertilizing methods and strategies were discussed at length in the last two newsletters. Refer to them as necessary. Continue with a regular balanced feed.

Wiring. Check plants daily that are wired. Branches will thicken rapidly and the bark can easily be disfigured. Many deciduous branches will already be set. Remove wire as needed by cutting with wire cutters along the curves, it is not worth breaking a branch to try to save some wire by unwinding it. If the branch is not set but the wire has become too tight, remove the old wire and rewire the branch, winding in the opposite direction.

Pests and Diseases. Bonsai should be checked often for signs of pests and diseases. Since bonsai are small and compact, it doesn't take long for a problem to spread over the whole tree. Treat immediately.   Watering the foliage helps to wash away aphids and red spider mites.

Trimming. Growth is at its peak now which means that special attention must be given to trimming new growth. On most plants growth is more rapid and vigorous at the top. Trim this top growth back hard to allow more light and nutrients to be distributed to the lower branches. This generally holds true unless a height increase or trunk thickening is desired. If this is the need, then trim where necessary to maintain the desired shape.

On finished bonsai, pinch and trim new growth as it develops and elongates to maintain the original design and profile. For trees in training, consider letting new growth elongate to thicken trunk and branches prior to pruning. Remember - always keep the health of the plant in mind.

Light. Rotate trees at least once a week so that all sides receive the strongest light available. 

September

Watering. During hot days it will still be necessary to check bonsai daily to see if they need to be watered. The weather should cool during the month, so the need for water should diminish. The amount of water needed will depend on the heat, the wind, the amount of foliage on the tree, the type of soil and the depth of the pot. Water the trees thoroughly, making sure that the pot drains easily. Poor drainage promotes root rot.

Generally the best method is to water the surface of the soil evenly, using a fine spray, until the water drains out of the drainage holes. Wait a few minutes and repeat. This ensures a thorough wetting of the soil. Try to avoid watering a tree that doesn't really need it. Wind can dry the soil's surface, while deeper in the pot it may still be quite wet. If in doubt check by scraping away the surface in a couple of places and adjust the amount of water accordingly.

A word of warning. Don't assume that the rain will always do the watering for you. A bonsai acts like an umbrella and shelters the pot from light rain. It is worth the time to check for adequate moisture, even in wet weather.

Feeding. Fertilizing methods and strategies were discussed at length in previous newsletters. Refer to them as necessary. New members may request copies of these newsletters. Reduce nitrogen this month, eliminating it completely by the last week. This will reduce the risk of forcing new growth that will remain tender and may be injured by frost. Continue to apply phosphorus and potassium to promote the growth of roots and trunks, strengthen the plant against disease and frosts, promote back-budding, and encourage the development of flowers and fruit, as well as hardening off late growth before winter.

Wiring. Watch trees that are still wired. In autumn trunks and branches will thicken, therefore you must check plants and remove any wire that is too tight as the bark can easily be disfigured. Many deciduous branches will already be set. Remove wire as needed by cutting with wire cutters along the curves, it is not worth breaking a branch to try to save some wire by unwinding it.

Pests and Diseases. Bonsai should be checked often for signs of pests and diseases. Since bonsai are small and compact, it doesn't take long for a problem to spread over the whole tree. Treat immediately.

Trimming. This becomes progressively less necessary this month, with the exception of junipers which may continue to grow for awhile yet. Trim where necessary to maintain the desired shape of the tree.

Pruning. Prune only if really necessary. Pruning now may encourage new growth which will not harden off before winter.

Light. Continue to rotate trees at least once a week so that all sides receive the strongest light available. Toward the end of September start to "harden off" indoor bonsai that have been kept outdoors by gradually moving them to a location with less light. Continue to do this over the next few weeks to condition them for movement indoors.

Repotting. Autumn is a good time for repotting flowering quince, apple, persimmon, pear, and early varieties of apricot and cherry. Rapidly growing trees such as tamarix and willow can stand a second repotting. Nursery stock can be root pruned, but do not cut back as much as when root pruning in the early spring. The roots will not have as much time to adjust before cold weather comes.

October

Watering. The weather should cool during this month, so the need for water should diminish. Reduce watering accordingly. You don't want to drown them in the fall after keeping them alive through the heat of the summer!

Feeding. Now is the time to switch to no- or low-nitrogen fertilizer, helping the trees to put on more wood and encourage root growth to get ready to go through the winter. Fertilizing methods and strategies were discussed in previous newsletters.

Wiring. In autumn trunks and branches thicken, therefore, you must check plants that are still wired and remove any wire that is too tight, as the bark can be easily disfigured

Weather. Watch out for extreme changes in weather. If sudden frosts are predicted, shield your sub-tropical trees from the cold - bring them in to protect tender foliage. Tropical trees may need to be moved inside to their winter homes. If there is a spell of warm weather, temperate plants may be fooled into sending out new growth that will be easily damaged by the next frost. Avoid this by keeping trees in a cool, shady location during very warm spells.

This is a good time to start thinking about where your temperate bonsai will overwinter. During most years in our area, trees don't need to be moved until December, but it is good to be prepared. One of the surest ways to kill a temperate bonsai is to keep it inside the house during the winter. The trees need to go through all the seasons, protected from extreme cold and drying winds, but they do need the dormant season.

Maintenance. Clean out the trash, dead leaves, seed pods, etc. from your bonsai in preparation for overwintering. You may want to spray your tree with a fungicide and insecticide to cut down on unwanted pests.

November

Watering. The weather should cool considerably during the month, so the need for water will diminish. Slack off on the watering now, water only as needed.

Feeding. Now is the time to switch to the no- or low-nitrogen fertilizers, helping the trees to put on more wood, encourage root growth and get ready to go through the winter. Fertilizing methods and strategies were discussed at length in previous newsletters. Refer to them as necessary. New members may request copies of these newsletters.

Wiring. Watch trees that are still wired. In autumn trunks and branches will thicken, therefore you must

check plants and remove any wire that is too tight as the bark can easily be disfigured. If the branches have already set, remove the wire.

Seasonal Care - Focus on Wintering. At this time of year, there is always some uncertainty as to the protection required for Bonsai during the cold months ahead. There is no formula that will allow overall coverage of the diverse plant material available. In addition, climatic conditions may vary appreciably within each plant hardiness zone. This is further complicated by scattered microclimates that may exist within each zone. As a result, the information supplied here will focus on the three generally accepted categories of grouping plant material. These are identified as Tropical, Subtropical, and Temperate.

To be most effective, it is recommended that members obtain a detailed map of plant climatic zones. These zones are based on average minimum temperatures for the area within each zone. the information in these maps is supplied by the United States Department of Agriculture. The maps themselves appear in plant catalogs and many horticultural publications.

Raleigh and the surrounding area is close to the transition between zones 7 and 8. Zone 7 has an average minimum temperature of 0-10 degrees Fahrenheit. Zone 8 is somewhat warmer at 10-20 degrees Fahrenheit. To ensure adequate protection, we should consider ourselves in Zone 7. As a plant's hardiness is determined by its cold tolerance, it becomes obvious the plants that cannot endure a cold temperature of 0 degrees Fahrenheit will suffer damage or death if not protected from such conditions. One other factor must be taken into consideration. The hardiness is based on plants growing in the ground, not in containers exposed to the elements. As the root zone is more tender than above ground growth, the same plant growing in a container can be damaged at temperatures 15-20 degrees higher than if it were growing in the ground. To protect Bonsai properly, it will first be necessary to identify the species under consideration. This may be done by consulting textbooks written specifically for the purpose, by visiting local nurseries or the N. C. State Arboretum, or by consulting with other TBS members or horticulturists.

Once the plant has been identified, the hardiness (minimum tolerable temperature) is determined using the same references stated previously. The hardiness should place the plant into one of the three general categories (temperate, subtropical or tropical). Use the following guidelines for each category.

Temperate Region Plants. Keep the Bonsai container on the display bench until it is subjected to two hard frosts. This should ensure dormancy. They may be left on the bench throughout the winter, but should be given protection when the temperatures drop to 20-25 degrees Fahrenheit. This may be accomplished by moving them into a cold greenhouse, a cold frame, onto an unheated enclosed porch or a garage. They may also be placed under the display bench or eaves of a building and then mulched with pine straw or bark up to the first branch. Semi-cascades and cascades may be tipped onto the side of the container as long as drainage is not impaired. Try to place the plants out of direct sunlight to discourage them from becoming active too soon. Construct a shade screen if necessary. Periodically check and water if soil becomes dry. If left outside, especially on the ground, check for intrusion by rodents. they will forage and eat bark from some trees. Unless absolutely necessary, do not take temperate Bonsai into the house or other heated areas. Make an effort to keep them in an area where the mean temperature remains below 45 degrees Fahrenheit and slightly above freezing. Deciduous trees require no light during dormancy. Broadleaf and needle evergreens will remain healthier if allowed to receive some daylight.

Subtropical Plants. These Bonsai must be given more protection than temperate Bonsai. They should be kept in a sheltered area with daytime temperatures around 40-55 degrees Fahrenheit. Night temperatures should be 5-8 degrees lower. When necessary, apply water at room temperature. Do not expose them to freezing temperatures, but do allow them to receive ample daylight but not direct sun. Subtropical plants also require a dormant period during the cold season. Do no apply any nutrients during the dormant period.

Tropical Plants. In their natural growing areas, tropical plants experience fairly constant temperatures and light conditions throughout the year. They thrive in the tropics where temperatures seldom fall below 60 degrees Fahrenheit. To simulate their natural growing environment they must be placed in a heated greenhouse with temperatures maintained at least between 60-75 degrees Fahrenheit during the day. Night temperatures should be lowered by 4-8 degrees, but never let it fall below 60 degrees. These plants should not be placed close to a window due to the temperature drop in the immediate area. Tropical plants will continue to produce new growth during this period but at a somewhat reduced rate. As a result, they should be pruned when necessary. Reduce fertilizer to half the rate applied during the peak growing seasons of Spring through Autumn. Tropical plants do best under humid conditions. This is unlikely to occur unless some method is used to increase the air moisture content. This may be a simple device such as a humidifier or even a humidity tray filled with gravel and water placed under the Bonsai.

For those of us that do not have the convenience of a greenhouse, our homes must act as a substitute. The general growing conditions and requirements remain the same for indoor placement. What the Bonsaist most do is attempt to simulate the natural tropical growing environment inside the home. This may not be an easy task. Some may think that the solution is to grow or purchase an "indoor" Bonsai. This is very misleading, for it implies that the plant was specifically grown for indoor culture. In reality, there is no such thing as an "indoor" plant. Plants are placed indoors because they cannot tolerate the subtropical climate experienced in temperate areas. With this in mind, a grower stands a better chance of success knowing that they must create an artificial environment that simulates the plant's natural growing habitat. 

December

In the Triangle area all outdoor plants should be dormant by now, all tropical and semi-tropical plants should be inside.

Outdoor, dormant bonsai still need to be cared for over the winter. Protect trees against extreme cold and drying winds. Trees may be buried in the ground up to the first branch (surrounded by mulch, not soil), stored in a cold frame, or kept in an unheated garage or shed. The goal is to keep the trees cool so that they remain dormant, but prevent them from being subjected to rapid freezing and thawing.

It is important not to let the trees dry out completely. They will use a lot less water during the winter, but they need to be checked periodically. When you do water, water thoroughly, so that the water drains out the bottom. This will allow you to assess the drainage of each pot and ensure that the roots at the bottom do not dry out. If the water does not drain out easily, you will need to find out why and correct the situation to prevent the roots from rotting from too much water. Never water when the trees are frozen.

Check for insects, pests and mildew. A fungicide spray will keep the mildew down.