Most bonsai begin their growth cycle during this month, and consequently require more care and attention than when they were dormant. Also, like February, March is a month of possible extremes in temperature, and if these occur, extra care is in order.
Nearly all healthy bonsai will have new growth by now and should be kept in a sunny airy place. Be sure to rotate plants often, changing their positions so that each side will receive an equal amount of sun. If this is not done, one side or the other will become stunted or weak, while the other side will over develop.
Same as March, but be careful of days when an extremely hot sun, accompanied by a warm drying wind may require more than the usual amount of watering. Do not depend on light showers. Pine trees that do not need any more growing should be kept dry even until the new candles wilt down. This method will also keep the pine needles short and strong.
Trimming & Pruning
The long sprouts thrown out by young deciduous trees should be nipped back from time to time this month, leaving two or three buds. On the older deciduous trees they should be left until they harden and cease to grow. The longer they are left on, the more strength they can impart to the tree as a whole. It is best not to remove them until the following dormant season.
The new candles on older pines should be pinched back during April, but leave the candles on young pines and vigorous older pines for another month.
As growth is rapid during April, it is a period when a tree's healing process is most efficient. It is therefore a good month in which to kill and strip the bark from any heavy branch to make a JIN.
April is the best month to graft persimmon, and any other late spring sprouting deciduous trees.
Same rules as March. When transplanting a pine, save a small amount of soil which has some white fungus. Mix it with the new soil mixture and place it in the bottom of the pot. Pine and this fungus have a joint living relationship.
April is the first month to begin fertilizing. Do not fertilize fruits or berry bonsai with strong nitrogen content fertilizer such as blood-meal. Instead apply bone-meal which will help keep fruits and berries from falling off. Super phosphate is excellent for this too.
When new sprouts appear, watch for aphids and cut worms. Do not use a strong solution to spray or it may damage more than the insects.