You may read how easy juniper bonsai care is. However, like any bonsai they are easy, if you know how.
Consider this bonsai as an "outdoor tree."
Most are sun loving!
Growing them indoors is possible, but definitely much more complicated, and not recommended.
Junipers should be kept moist but not soaking wet. They even like to dry out a little between waterings. If you have fast draining soil, watering should not be a problem in your juniper bonsai care.
If you have 'heavy' soil, it holds a more water and often stays too wet. This situation can eventually create a bad fungus in the soil. Long term, it can kill your tree. It is especially important for junipers to be in coarse, fast draining soil ("bonsai soil".)
One of the obljects of bonsai is to keep them about the same size as when they are considered "finished." To accomplish this, root pruning is required. Root pruning also keeps your bonsai healthy. How often depends on the variety of plant, the size of the pot and your climate.
For junipers, the best time of year (in most climates) is fall or early spring. For a detailed description of root pruning read this article by bonsai grower Brent Walston.
If you have plants of any kind, you will occasionally have pests. One of the most insidious is the red spider mite ... and it especially loves junipers.
The first clue of mites is usually a grayish cast to the needles. A clue to the more advanced stages of this pest is dense cobwebs.
Since mites are almost invisible to the naked eye, a simple way to check is with a white piece of paper. Place the paper under a branch, tap the branch and look closely. If you see something red, tiny and crawling around on the paper, you have a problem. Mites can easily spread to other plants.
.Don't wait, treat problems immediately!
Another pest (and potential disaster) is the Juniper twig girdler. (Fortunately, it isn't a problem that often.) Periploca nigra, is a small moth whose larvae can significantly damage a tree. It's difficult to see, because it chews under the bark.
Sprays do not kill borers! The best way is to eliminate them is to find them and dig them out. Sometimes there is more than one.
Even if you think you've got them, use a systemic insecticide.
The cycle of this moth is scary. Once they pupate, the moths return to the same plant to lay their eggs. The entry point is difficult to see without a magnifying glass. The first sign may be frass (looks like sawdust.)
And sorry, but this is not the only larvae that can attack your bonsai, read more about "frass," borers and what to do!
Hopefully, you will never get any of these pests. However, they are a good reason to make 'daily observation' a part of your juniper bonsai care.