Keeping a bonsai tree is a year round commitment. Even though you might have less maintenance to do in the summer, you still need to keep a special eye on your bonsai in this volatile season. The summer care needs of bonsai trees will differ slightly with each species, but for the most part you need to keep watch of their temperature, their growth and their humidity.
You can move your bonsai tree outdoors during the summer, but don’t just kick them out of the house for three months and expect to have a living bonsai afterwords. If your area gets very hot in the day and then cold at night, you need top bring your bonsai indoors during the night.
If the heat is incredibly oppressive and your bonsai tree is not of a tropical species, you will also have to bring it indoors. Because of the increase in light and heat, you will need to water your bonsai tree more often. When you spray your Bonsai tree with a non-toxic environmentally friendly pesticide, don’t do this when the sun is as its peak.
Summer is the season for rampant growth among plants, which is not a boon in the case of a bonsai tree. You should have prunes the roots in spring, but you will also need to constantly check for sudden new growth that may quickly turn your bonsai into a full-sized tree. Depending on the species and the individual bonsai tree, you may have to pinch and prune weekly.
The proper humidity levels are another concern for summer care of your bonsai tree. When your bonsai is outside and it’s humid, you don’t have to worry about the humidity levels so much. What you are worried about is dry air in the house, which can often happen when you have air-conditioning. Try to keep your bonsai away from a draft, as this will also dry it out.
A good way to counter dry air is with misting your bonsai tree (as opposed to a full watering). You just fill a plastic misting spray bottle with water and give the bonsai a going over as often as is needed. Another good way to keep dry air from harming your bonsai is through the use of humidity trays or pebble trays. They are just shallow trays with pebbles and water in the bottom. The water in the pebble tray is not to touch the bottom of your bonsai’s pot.