As we know bonsai are our beloved tree; that needs full time caring. If a bonsai is left with no care for a certain period of time, he might fell sick and die. In order to avoid your bonsai from losing leaves / falling off / turning yellow and dead branches, you need to proper care for it; to bear in mind those most important aspect in growing and caring bonsai (watering, light, humidity, temperature, air circulation, soil, fertilization).
Thus if it happens that your bonsai leaves turn yellow, there are some possible causes for that:
- First of all - some bonsai defoliate (drop leaves) when their environment changes. If upon the tree’s arrival some leaves have dropped or turned slightly brown that does not mean the bonsai is unhealthy. Defoliation is the natural result of being in the low-light environment of a shipping box. In some cases, Styrofoam popcorn must be used to safely pack unusually shaped bonsai. Organic popcorn packaging made from corn starch reacts with moisture from the trees and can dissolve. When you receive your tree, place the box in a shaded area to unpack. Inspect tree for damage to branches or leaves. Water soil if dry. Place each bonsai in protected shade for at least one week before moving to a sunny location.
Beside this natural cause, you could think to two more causes:
- First would be dehydration, which is the obvious choice. To remedy this, you need to consider feeding enough quantity of water (be careful not to drown your bonsai).
- The second possible cause is insect infestation. Meal bugs and spider mites are the usual culprit. Get yourself some plant-safe insecticides and get rid of the insects that plague your bonsai.