If I have just purchased a bonsai, what is a good watering routine that I should start with and how should I adjust this routine regularly?
Learning how to water bonsai can be notoriously difficult and it is the main art you will need to master before you even consider pruning or wiring your plant.
It is likely before you master watering bonsai you will likely loose several plants due to over / under watering. Hopefully the tips below will help minimise your losses.
Looking after a bonsai requires daily maintenance; regardless of summer or winter you will need to check the water level of your plant every day.
The best indicater of how much water your plant has is the surface of the soil. You want to aim to keep the soil dark, but not damp. I was told to use the back of your hand on the surface of the soil and if it feels damp that is good, but if it is wet then it has been overwatered. If it is damp then no need to add any more water.
If it is dry then you need to water the plant. Soil in your plant should drain reasonably well so that your plant can absorb water easily through the soil, but shouldn't be too loose that water goes straight through it.
When watering you should be able to keep pouring until water comes to the base of the tree and the soil is completely saturated then leave the plant to slowly drain. If the top of the soil is dry because there is not much soil in the pot it is likely all of the soil is dry so don't just put a couple of slurps in, make sure you give it a good soaking.
In summer you may need to do this twice a day, in winter approximately once every three days.
If you find that your plant is very dry and the leaves are wilting you can soak the entire pot in a sink or tub to the same level as the top of the pot. Warning: don't do this immediately in the middle of a hot day. If the plant is wilting in hot sun, move it into the shade and give it a soaking once it has cooled down.
Make sure when watering that the trunk of the tree and any exposed roots aren't left soaking in water for an extended period of time.
The last two tricks I have for keeping an eye on water level in my bonsai:
If you have a layer of moss on any of your plants this is helpful in keeping an eye on your plants. Moss likes to be slightly damp, have some sunlight and may grow mouldy if it is too wet. It also sits at the surface of your por so can be used as a good indicator of how damp the soil is. Keep your moss happy then your plant should stay happy.
My second tip is to keep a plant next to your bonsai that is made up of mostly water like an impatiens. If you keep it in a smallish container it will react quickly to a lack of water, but will perk up quickly once it has been watered. Don't water it regulary, just let it tell you when it needs to be watered and this will also be a good time to give your bonsai a good watering. Impatiens are pretty hardy so won't die from the experience. In summer they will like a daily watering in winter they will need a watering about once every two or three days, the same as your bonsai.