When considering growing bonsai trees indoors you have to bear in mind that bonsai are still trees, and trees in their natural state belong outdoors. There really is no such thing as an indoor bonsai tree. Being a "tree in a pot" (bonsai) makes no difference to that.
Many bonsai beginners visualize themselves with a collection of bonsai trees indoors, and that is probably a result of seeing pictures in books and magazines showing bonsai in an indoor setting, or visiting a nursery where the trees are under cover temporarily for convenience.
Does that mean it's not possible to keep bonsai indoors? No, but there are a number of provisos.
First of all, a healthy tree will thrive when in its natural setting. If it is not in its natural setting (such as indoors) then it may still thrive but this will depend on special care being taken to ensure that it enjoys an environment that is as natural to it as possible.
It may be easier to grow bonsai trees indoors if you live in a warm climate, but of more importance is the type of tree you wish to grow indoors. A temperate tree is at home in a temperate climate and will not like being brought indoors except in severe winter weather, when special measures should be taken to accommodate it with regard to temperature and light.
The main reason is that such a tree needs a lengthy period of dormancy each year, and that is brought on by low temperatures - around 10C or lower for 40 to 50 days. If you deprive your temperate bonsai of this cool or cold period then it will appear to carry on without ill effect for anything up to a couple of years, but it will actually be fatal.
If you live in a cold climate then even temperate bonsai trees will occasionally need protection from the cold. This is because their roots are in a shallow pot and are therefore not afforded the protection that their larger cousins in the wild are. It is common practice in these circumstances to give winter protection to even temperate trees in very cold weather by bringing them indoors, but extra steps must then be taken to ensure adequate levels of light and humidity for the trees not to suffer.
What about tropical and sub-tropical species, then? Generally speaking these can be grown successfully indoors, and would in fact need to be kept indoors in cold winter weather. However, their natural cycle should be imitated as closely as possible, as even though they don't have a period of dormancy as such, they still have a slower growing period in the winter.
Special measures have to be taken to ensure they receive adequate light. Putting them in front of a window is not good enough. The glass blocks out the essential UV light (needed for photosynthesis), and can even give the tree leaf-burn if the sunlight is fierce. The quantity of light will in any event be totally inadequate, unless supplemented with around 80W of artificial light around 6 inches above the plant for at least 12 hours a day. Either standard or fluorescent lighting can be used.
The atmosphere inside many houses is more arid than in the desert. This is usually due to central heating or air conditioning. Each indoor bonsai tree should have a sufficiently humid atmosphere, such as by being kept next to a pool of water shallow enough to dry out each day. This will prevent the build-up of algae and discourage pests.
Don't place any trees near to radiators as these areas commonly have extreme temperature ranges. Your bonsai plants need fairly constant temperatures, without extremes. Ensure there is an adequate degree of air circulation, but avoid drafts.
You will have to constantly check for moisture levels. On no account must your bonsai trees be allowed to dry out. Whilst watering outdoor plants every day is a sound policy, indoor plants have to be monitored for their requirements. They won't necessarily need watering every day. This will depend on the species and their environment. But when you do water them do so with a watering can with a rose head. Water in short bursts, to allow absorption by the soil, and repeat until water is dripping from the drainage holes at the bottom of the pot.
Indoor plants should be fed fertilizer every two weeks, according to their individual requirements. You will also have to check for mite infestation regularly. Examine the underside of leaves for signs of webbing or debris.
So, to summarize - yes, you can grow bonsai trees indoors, but you have to be prepared to take special measures to ensure their special needs are met and their environment is as close to natural as possible.
Copyright 2008 Water Fountain Gardens