Bonsai sprout is loosing all of its leaves, help!

Question

My boyfriend planted this bonsai from a seed almost a year ago, so not exactly sure which type it is. We keep it watered and it sits on the window in our bedroom, where it receives fresh air, sunlight, and wind. The past week or so we noticed that some of its tiny branches were becoming dry and fragile. This morning, when I went to water it, two more of its branches/leaves fell off completely! Now it only has two tiny leaves on the very top. Hopefully you can see the small branches that fell off on the soil.

The base of the sprout is still very strong, and the plant itself is not drooping or wilting; has a twig-like feel yet flexible and strong. We are complete beginners at caring for a bonsai, and are wondering if anyone has any experience or tips regarding what to do? Should we replant the entire bonsai? Maybe water it more often (soil was completely dry a few days ago, even though we water nightly, so maybe need to water more)? The bonsai is inside all day, and I am not sure if I should be putting it outside at all. We live in Hawaii, and the days can get pretty hot and humid here, especially at this time of year. Additionally, the sun is really strong; I've had other plants get sunburnt. Any help is greatly appreciated]1

Answer 1

A pretty common tree with a compound leaf in Hawaii is the Acacia family. It's a huge family with many different members and there are many particularly known for suitability for bonsai cultivation. The leaf loss could be due to overwatering so make sure that the soil can drain freely; trees in pots can become waterlogged if their owners are too kind to them.

An essential skill for any bonsai owner is to have confidence in upending the pot and removing the root ball for inspection and reorganization of the root. You may just find that the roots are wet and brown, unable to support the leaves. Outside is definitely better and only water when the soil is dry.

Acacias are very tough, so it might well come back if you can change the environment.

Answer 2

All that I can tell from the photo is that it has compound leaves. Rowan and zanthoxylem are two species I know with this kind of foliage, but not the only ones with compound leaves. Certainly Rowan (mountain ash) requires dormancy, meaning to be in temperatures below 40F/5C for a period of time for buds to produce new leaves. Being indoors just won't do for them. Zanthoxylem is semi-tropical and may not require dormancy, but does need more sunlight than it would likely get on a window sill. Even tropical species will slowly die when kept inside, simply because of inadequate light.

Put is outside, if you possibly can.