By Les Lonsdale

    Spring is usually considered the busiest time of the year for bonsai enthusiasts, and for good reason…there’s just SO MUCH TO DO! But this is also the most exciting season because we get see our trees entering the next phase of their development, and we have a short ‘window of time’ to make changes where needed, in order to guide them in the proper direction. So, let’s get to it:

1. Repotting – Only repot when the tree becomes root-bound, as repotting every year will stunt the development of the tree. Keep a schedule. Some trees might need repotting every year or two, but some can go 3-4 years without it. Learn the growing habits of each tree and act accordingly. Start with deciduous trees and repot before bud break – after leaves have opened, much of the trees’ energy store has been expended. To repot at this time would destroy many of the new roots and the tree might not have enough energy reserves to replace enough of them to supply sufficient nutrients and water to nourish the top growth. (exception is mature japanese maples, which respond better to repotting after leaves have begun to open.) Evergreen deciduous and conifers can be repotted next, because the timing is not as crucial. Flowering trees can be repotted after the flowers fade, if you want a show of flowers. If you are more interested in plant growth, pluck off the flower buds in early Spring and repot with the other deciduous trees. Let the trees dry out a little before repotting so the soil will be more easily removed from the roots, lessening the chance of breaking them off. Also, the tree will be more supple and thus easier to wire, if you plan on doing that at this time. Be sure to anchor tree firmly in pot using wires. If tree is not very stable, winds will move tree and break fragile new roots as they try to grow. After repotting, immerse entire pot in water for several minutes until the soil mix is saturated. Some soil ingredients do not wet out easily and a simple top watering may not sufficiently wet the entire volume of soil and roots.

• Watering – Be careful not to over water your newly potted / root pruned trees during the first month, as they may not have developed enough new roots to absorb very much water, and if they do have enough, it will create larger leaves and longer internodes than if you water sparingly. However, don’t let the soil dry out completely, which will kill the tender new roots. Some who use automatic sprinkler systems during most of the growing season, prefer to hand water their trees in the Spring in order to better regulate the amount that each tree receives.

• Fertilizing – Don’t fertilize newly repotted trees for at least a month as there are not enough new feeder roots yet to absorb the fertilizer, and inorganic fertilizer can burn new feeder roots. Also, only fertilize trees in training in the Spring, using an inorganic fertilizer. Mature trees should not be fertilized until late May or until after the first flush hardens. Fertilizing encourages coarse growth with long internodes, which is ok on developing material, but not on mature trees. After first flush hardens, begin a fertilizer program with organic fertilizer, preferably. Pines should be given a nitrogen-free fertilizer in the Spring to retard the growth of new shoots, while maintaining the health of the tree.

• Developing shorter internodes – For mature trees, in order to develop shorter internodes, stay on top of the spurts of new growth which will happen in the Spring. When you pinch out new shoots, the tree has to expend energy to replace them and the length of the new replacement stem will be shorter. Also, this will increase ramification, as where you pinch will develop 2 new buds. Placing your tree in as much sun as it can tolerate will also shorten internode distance. As a rule, one year, pinch or cut off any shoots that won’t be part of the final design of your tree, but the next year, do not make any cuts until late May. If you keep a tree pinched tight every year, the health of the tree will decline. The exception would be ‘sacrifice branches’ which are left on for a while in order to thicken up a trunk or a limb, and then cut off later. For trees in training, do not pinch or cut anything until late May.

• Pest/Disease control – Plan a pest and disease control program and buy your ingredients early in the Spring, so you will be ready to go. There are myriad’s of bugs and spores just waiting to attach themselves to those tender young leaves. Most insects attack the underside of the leaves, and many are hardly visible with the naked eye, so don’t depend on being able to see them from merely a casual inspection. To stay organized, perhaps you could get a calendar and pre-mark the days you will apply pesticide/fungicide and the days you will fertilize. Some recommend granular systemic pesticide and fungicide over sprays as they can be more effective and easier to use than sprays. Catch problems early and nip them in the bud! Spider mites favor hot, dry conditions, so if you mist and/or water your foliage frequently, it should help discourage them from making their home in your trees. By a gentle tap on your tree, you will know if you have white flies for it will send them flying about.

• Misc. – Thread grafts should be done very early in the Spring, preferably before the buds begin to swell, as tender swollen buds can be knocked off easily as the branch is threaded through the small drilled hole. On the other hand, other types of grafting and air-layering should not be attempted until very late in the Spring when the tree is in full leaf and the sap is flowing. March-April is the time to root any hardwood cuttings that were taken in the Winter, and also any semi-hardwood cuttings taken this Spring. Make a fresh cut, apply some rooting hormone, and place into a sandy mix. Cuttings take much faster and efficiently if you can apply some bottom heat, but I have found that most cuttings root OK without it. Cover the root bed with a large Tupperware tote in order to hold in humidity but keep out of full sun. Collect moss that grows in sunny locations, not that which is found in shady, wet areas, as it would have a harder time adapting to the new sunnier environment. You can find good moss in parking lots between the cracks in the pavement, or in gravel lots sometimes. And lastly, keep written records (and pictures) of your trees. Someone once said, “A short pencil is better than a long memory”, and that is very true. Records will remind you of what has been done to your tree in the past and will help you keep track of it’s progress in a more organized way. You’ll be glad you did.