Flowering Bonsai is a vast part of Bonsai and not an easy subject to condense into one article. However, I have been asked to touch on the subject, so here goes…
Most Bonsai species would develop flowers at some point if left to grow into bushes, but we don’t see flowers very often because most plant species produce flowers at the ends of long new shoots and these are the shoots that need to be removed to keep the tree shape. Some species, like Bougainvillea, produce flowers from old wood (like the trunk) fairly easily, and with some careful pruning one can still retain the tree shape and be rewarded with a good display of flowers.
There are, however, not too many indigenous species that are well known for producing flowers. Erythrina Caffra can produce some wonderful flowers, but it requires subtle techniques to coax even just a few buds out – even experienced Bonsai growers struggle.
The most famous flowering Bonsai come from the Azalea family. Of this family, a group called Satsuki is particularly well known and includes thousands of varieties all originating from the Tokyo region of Japan. Satsuki definitely deserves a full article – look out for this in future issues.
When dealing with flowering Bonsai, it is important to realize that even though one can reduce the size of the leaves of most trees, the flowers and fruit do not reduce in size. The only way one will get small flowers on a bonsai is if the variety of plant is one that already has small flowers. One can perhaps reduce the leaves of a citrus Bonsai to quite a degree, but the subsequent fruit will be of the regular size that one buys in the supermarket.
Something else to consider with flowers, is that flowers are the plant’s way of attracting insects and birds for fertilisation and reproduction. Most plants produce flowers from middle to late winter so that their own offspring begin to grow in spring when the conditions are best. If the flowers bloom naturally in a dry period, too much water during this period will not produce flowers. For a good show of flowers in almost ALL plants (garden plants too), one needs to hold back on the water for a period of time – normally two weeks to a month – leading up to the display time. Water less but still give it water otherwise the plant will die. Once the plant blooms one must take care not to water the flowers themselves as this can stain them and even make them rot.
Flowering Bonsai needs more fertiliser than non-flowering Bonsai. Fertilisers contain three main ingredients; Nitrogen, which promotes the growth of stems and leaves; Phosphate, which is needed for buds and flowers and improves the colour of the blooms; and Potassium, which improves the general strength of the plant and also helps with the growth of leaves and stems. Most fertilisers will display the various quantities in a ratio like 5:3:1 (5 parts Nitrogen, 3 parts Phosphate, and 1 part Potassium). A ratio like this, with a high middle number, will be a good one to use on flowering Bonsai shortly before it is to produce flowers. Avoid fertilising towards the end of summer though, because the plant will soon go into winter sleep mode and all the additional Nitrogen would either get wasted or worse, confuse the plant’s natural clock, and it might begin growing again at a time when it should be resting.
Finally, dead blooms must be removed from the tree as soon as possible. This is because while they remain on the tree it will attempt to revive them and continue to give them food. Once they are removed the tree can use the nutrients for the remaining flowers.
Here are some flowering species to look out for, but there are many more so don’t be afraid to experiment:
Wisteria – pictured here.
Pyracantha – small red or white flowers and small red berries.
Cotoneaster – white or pink flowers.
Serissa Foetida – small white, pink or mauve flowers. It can be very sensitive to temperature change. Avoid variegated leaf varieties.
Azalea – Satsuki in particular.
Grewia Occidentalis (Crossberry) – pink or mauve flowers.
Dalbergia Armata and Dalbergia Multijuga – clusters of small white or creamy yellow flowers.
Coddia Rudis – small bell-shaped flowers.
Erythrina Caffra – large orange to red flowers.
Eugenia – clusters of small white aromatic flowers.
Schotia Brachypetala, Schotia Capitata or Schotia Latifolia – all three varieties can produce beautiful red flowers in dense bunches.