Pinching back (finger pruning) and trimming of terminal growth results in secondary growth further back on the branch. The result is increased fullness of the foliage which causes the tree to appear more mature. If such grooming is not done, the most vigorous shoots will grow thick and strong. The upper branches of a tree always grow more vigorously than lower branches. Failure to groom the top branches will encourage top heavy growth and the withering of the lower branches. If done properly pruning will result in delicate twigs at the apex and strong lower branches.

Pruning of conifers such as junipers, spruces, cedars, larches and cryptomeria is done with the fingertips. Hold the branch (near the tip that is to be pruned) between the finger and thumb. With the other hand, grasp the leading shoot and gently but firmly pull the shoot straight towards you in one quick motion. On a mature bonsai you should pinch shoots all over the apex and on the lower branches as necessary.

Pines and deciduous trees are usually scissors trimmed. Hold the end of a deciduous stem. Then use your scissors to cut through the stem immediately above a leaf. Pine candles can be trimmed by placing a fine, sharp scissors at the base of the candle - make sure not to cut any surrounding candles. Many club members prefer to use their fingers to twist off two thirds of the candles. Pine candles can still be shortened in May. If there are three or more candles to each bunch start pinching the largest, then in a few days the next in size, and so on until all have been reduced. This procedure promotes new breaks on the branches, shortens internodes, reduces the length of the needles, and encourages growth of the weaker candles.

When your spruces show new growth use the same candle pinching technique to promote breaks and control the length of internodes. Your junipers will need constant plucking during the growing season.

Excess moisture and sunshine will cause long internodes on deciduous trees. Let the leaves develop. Then be sure to cut back to two or three leaves on each branch. Do not prune the entire tree at the same time. Wait. At seven to ten day intervals you can prune about one fourth of the tree each time. The desired ramifications of your bonsai are achieved mainly as the result of spring and early summer pruning. Do not neglect pruning your trees in May.

By now the sawfly has descended on the pines and the aphids on the quince and maples. Soon we will have really hot weather and the red spider mite will wreck havoc on our junipers and Alberta spruce. Inspect plants daily for any signs of insects. Red spider mites can be identified by placing a piece of white paper below a branch. Tap the branch. Then inspect the paper for minute dots. If the dots move spider mites are present. A hard spray of water will discourage the insects. If they persist, spray with Kelthane or Malathion. Always read the labels of insecticides and follow the instructions.

Most of our members prefer a coarse soil because it promotes root growth and prevents root rot. However, such a soil retains very few nutrients. Thus, it is important to apply a liquid fertilizer on a regular basis. I try to remember to fertilize at half strength every week. In addition I use Osmocote (a slow release fertilizer) whenever I repot.

Watch closely all trees that have been wired - especially maples. May is a time of rapid growth. Wire cuts can easily occur. Remove a wire that is about to cut into a limb. You can always rewire.

(Editor’s Note: What Jim says about rapid growth is absolutely true! I wired my Japanese Maple last year. I did it kind of late, so when it came time to over-winter, I left the wire on and stuck it in the ground. I checked it over the winter-no problem, everything looked fine. When I dug it up and started prepping it for this year’s round of hopeless labors, it still looked just fine. However, the recent warm trend has set off genuinely explosive growth, and wires that "looked fine" only a week or so ago now need to be removed. I also already yanked all the old wire off my semi-cascade azalea, and will do the same on my cascade juniper by the end of the week. It’s a simple rule: Ignore old wire at your peril. By the way, some of my trees are already showing signs of spider mites, so get ready!)