You should start to bring your bonsai out of their winter storage and place them on their benches. Sometimes you will find an excessive amount of moss. If moss covers the entire surface of the soil it will limit the flow of air and moisture to the root system and must be thinned. If moss is growing up the trunk of your bonsai it must be removed. Failure to remove moss on the trunk can be fatal.
Some bonsai experts clean the trunks of their bonsai in the spring.
Inspect each of your bonsai carefully and be especially alert for old wires. Remove all old wires. If old wires are not removed the bark can be permanently scarred because of the rapid growth of branches and the trunk in the spring. After you've removed the wire if the limb does not hold the desired position you will have to rewire the limb. A bonsai is, by definition, confined to its container.