Mahogany Row Studio

Bonsai Articles

Posted by Rob Kempinski on Jun 04 2007

You’ll find some hopefully interesting articles I have written about bonsai.

Japanese Black Pine in Florida Care Sheet - by Rob Kempinski, ©2007, Melbourne, Florida
Florida covers the southern range of Japanese Black Pine heat tolerance, yet with proper care they will thrive. But because of our long growing seasons, Florida growers can get more out of the Japanese Black Pine growing cycle that someone up north. Japanese Black Pine grow nearly 10 to 11 months a year here, barely slowing down for winter. That is almost twice the duration of a growing season in a northern zone. However, Florida is a big state, so the techniques mentioned here might not work as well in the northern tier, while they would work even better down south.
Three aspects dominate Japanese Black Pine development – growing conditions, needle thinning and pruning.
Growing Conditions – Between Christmas and the end of January, Japanese Black Pine enter what will pass for a dormant period. While the trees have slowed down, it is repotting time. It is safe to do root work on them. Highly recommended is pure sifted Akadama soil ( a clumpy type of clay soil from Japan) for Japanese Black Pine. The trees grow unbelievably fine root pads in this medium. The root hairs grow right into the soil particles. If you don’t use Akadama, then use a very fast draining soil – something like a mix of large particle sandblast sand, Turface, Haydite, or lava rock and a little pine bark. Japanese Black Pine like lots of water, but they don’t like wet feet. Therefore, when there is lots of rain fast draining soils will prevent root rot. When repotting, take it easy on Japanese Black Pine, especially old ones. Remove no more than a third of the roots at a time. Pay particular attention to how you handle the trunk as old flaky bark adds character to pines. Rough handling of the trunk will rub off the bark and spoil the look of the tree.
Watering a Japanese Black Pine entails a little more caution than a typical tropical plant. The trees need water only when the top level of soil has dried. The frequency of watering will depend on the root mass, wind, temperature and rain, soil composition, amount of sunlight and health of the tree. Do not blindly water every time you water your ficus or buttonwoods. This will kill a Japanese Black Pine. In the winter water intake goes down significantly. It is not unusual to water only every 3 or 4 days in the cooler months.
When using an inorganic soil mix, feeding becomes very important. Some pine enthusiasts advocate using organic fertilizer exclusively on Japanese Black Pine. But inorganic fertilizer, such as Miracle Grow granular, offer more convenience and less smell. Second, the organic fertilizer can really clog up soil during monsoon conditions and lead to root problems.
The key to growing a Japanese Black Pine bonsai is to encourage growth on some branches and back budding on others. On tropical trees a hard pruning and defoliation accomplish this. On pine trees, the approach differs with needle thinning and pruning at the right time being the method. But before you get to that, the first point to consider in working on a Japanese Black Pine is where the tree is in its design cycle. Seedlings, or recently pruned nursery stock have different development approaches than a finished bonsai. For instance, needle size reduction should not be practiced while striving to grow branches. Also, as with all tress, only work on healthy Japanese Black Pine. Applying these techniques in our southern zone could be fatal to a weak Japanese Black Pine.
Needle Thinning – by Christmas, the Japanese Black Pines have finished with the last batch of needles. So they need to be removed to make room for more needles, to get sun on the branches to let interior shoots grow and encourage back budding, and to get air circulation inside the tree to prevent fungal attacks. With a healthy tree, needle thinning again in August. will encourage a second flush of growth. The theory being the tree still has almost 4 months to grow. This is equal to the total growing season in more temperate areas. Also remove damaged needles (broken while wiring, by insect chewing or by fungus) throughout the year.
Removing needles to get the inside branches to grow represents one aspect of energy balancing. Many authors mention this in mysterious ritualistic sounding techniques – but it is really simple. If a needle shadows another needle, it won’t do its job of photosynthesis. It will eventually fail and whither. Similarly interior buds will not develop. A Japanese Black Pine strives for maximum sunlight so it will divert its nutrients to the branches getting the most sun. Hence the top of the tree will grow more than the bottom. And outside branches will grow more than the inside. The goal in bonsai is to control this growth and to help the tree balance its vigor between the exterior and the interior of the tree and between the upper branches and the lower branches of the tree.
Needles make food for the tree. The more needles on any given branch the stronger and faster that branch will grow. By reducing the number of needles on strong branches, you slow down that branch’s ability to produce food and hence slow its growth. This gives the weaker branches a chance to gain strength as they grow.
In doing needle thinning, think of the rule of opposites. Strong branches have less needles after pruning. Weak branches have more needles. Leave at least two pairs of needles on all the vigorous branches. On weak branches you can leave as many as 5 to 7 pairs of needles. The older needles are the ones that are on the woody stems of the tree. However, if you have been diligent in prior years needle thinning than the old needles will be the ones closer to the nexus of the branch. Often, new buds pop at the site of a plucked needle. Exactly how many needles to leave depends on how well you observe your tree and what you want to accomplish with each branch. Hard fast rules really don’t apply, especially in Florida with our long growing season.
Pruning Branches – When pruning branches you will be mostly cutting shoots, sometimes called candles. Occasionally, if restyling a tree you may need to cut a woody branch. Always do this after careful consideration as it takes significant effort to regrow a branch on a Japanese Black Pine. For balancing energy, keep in mind the state of the tree. For recently styled nursery stock, you may need a vigorous shoot to grow a tapering apex or to cover a chop scar. For sacrifice branches, let them grow with only a slight needle thinning and slight pruning.
Again, depending on the developmental state of the tree, some of the very vigorous shoots may need to be pruned, especially at the apex and periphery of the tree’s silhouette. Needle thinning may not be enough. The goal is to balance the vigor among the shoots. After pruning, it may be necessary to remove some current needles from the very vigorous shoots.
When pruning, general bonsai rules apply. Always prune to a bifurcated node. That is have only two branches emanate from a node. The reason is that Japanese Black Pine will swell more quickly if there are 3 or 4 branches emanating from a node. Avoid bar branches as they divert the eye and can also cause ugly localized swelling. On nursery stock though, it may be difficult to totally eliminate a bar branch as young pines tend to grow branches at nodes. If you absolutely can’t eliminate a bar branch – don’t. Use wire to move the mass of the foliage to either different levels or to hide the bar joint.
Never prune a branch so that no green remains. Japanese Black Pine will hardly ever bud from a branch with no needles.
Candle pruning encompasses an area of extreme variation in technique. For simplicity purposes, trim candles when they are just starting to show needles. Trim them as far back as you can consistent with the development needs of the tree. That is, for example, on a branch needing length, you can leave the trimmed candle several inches long. For a finished tree, trim the candles short. On a healthy tree, prune twice a year- when repotting in January and during the second cycle in August. A few weeks after pruning, new buds will pop at the cut sites. Go in with tweezers and remove all but two of the buds to permit bifurcation from the start. If a branch is weak, you can leave one or two extra buds for a few months but never more than a year. Always wire after needle thinning and pruning. Invariably you will break some needles while rewiring, so don’t totally finish the needle plucking until after you have wired.
Needle Length reduction – Only strive to reduce needles on established and healthy trees. Also keep in mind that needle reduction is temporary. The wonderful trees you see in the magazines or at the major shows have had their training regimens planned to have the short needles for the shows. The key to needle reduction is to time the pruning so that the needles have less time to fully grow in the remainder of the season and to cause the tree to expend its resources growing those smaller needles. This is a problem in Florida as our trees hardly stop growing. The twice a season needle thinning and pruning technique will reduce the needles somewhat. It seems counter intuitive, but cut the weak candles first and then about two weeks later cut the strong candles. This gives the weak candles more time to make the new shorter needles. You will have very short needles for the rest of the year. Much more could be said about needle reduction, such as reducing water and feed, or allowing the tree to get pot bound but those are techniques that individuals have to learn based on their own soil, watering, weather and other circumstances.