April Care Calendar
By April you should have completed all of your repotting. It is better to wait until summer defoliation time or fall to repot rather than risk killing the new growth on a plant by repotting after buds have opened. Pine repotting can be undertaken after candles have begun to elongate, but this should only be done in emergency cases and should be done with much caution.
The onset of the growing season means that bugs have become active as well. Keep an eye out for ants which bring in scale and aphids to suck the life out of your trees. Control the ants with bait around the base of your stands. Aphids can be killed with a mild soap or almost any insecticide. Scale, mealy bugs and many other pests might require systemic insecticide like Malathion or Orthonex. However, before resorting to these highly toxic compounds try using spurt of water to remove the pests; this will have to be done multiple times over a few days, but can give you the same results as the nasty smelling toxic chemicals. Keep your eyes on the plant afterward for signs of continued infestation.
Since your plants are now growing you should be fertilizing them. It is generally agreed that the fastest growth in bonsai can be attained by using a combination of slow-release fertilizer and fast-acting liquid fertilizer. The slow-release, either something like Osmacote or an organic balanced fertilizer like rapeseed cakes or powdered fertilizer, provides the plants with a constant source of nutrients which are not available in the soil since it is composed of almost all inorganic material. The liquid fertilizer gives the plant a boost of nutrients, but only for a short period of time right after it is applied. Most liquid fertilizer will be completely washed out of the soil the next time that you water your plant. Use Miracle grow or other brands in 1/2 strength once per week for fast growth.
If you want slower growth use only the organic slow release fertilizer applied once per month or less. This type of feeding should be used on refined trees, especially deciduous, and trees that you want to remain slender.
Pines should start off the season with 2-4 cakes of fertilizer or 2-4 teaspoons of powder buried in the top of the soil in pockets depending on the size of the container. Larger containers require more fertilizer.