By Jerry Meislik
This discussion is aimed at those who move their tropical trees indoors for the winter and then outdoors for the summer. I am one of those who can not move trees outdoors due to sudden cool snaps, even in summer, so that moving trees outside is not a possibility in my area.
In many areas of the county it is about the time of year to be thinking about moving trees from their indoor winter quarters to a position outdoors. During warm weather indoor bonsai can be moved outdoors to benefit from natural air movement, abundant sunlight and rain however this must be done with some preparation.
So what is likely to occur out of doors that will need some thought and preparation?
Spring has very variable temperatures that must be taken into account. Most tropicals will not grow when temperatures are in the range of 50F for the lows. It is best to move your trees indoors for cooler nights and outside for the warm days. Better yet, temperatures above 60F are much more likely to keep the trees happy and growing.
Increased temperatures will also mean increased watering.
Leaves and stems that are indoor adapted will burn if put directly into full sunlight. Plants kept indoors for the winter have soft, weak leaves and stems. and thin cuticle layers. These weak areas will not tolerate direct sun and will burn. A thoroughly burned tree will often have a spontaneous leaf drop and lose all its leaves. This naturally weakens the tree and forces it to use precious reserves of energy to produce new leaves.
Trees must be placed into full shade for a week, then partial shade for a week and then to dappled sun and finally to full sun. Done gradually in this fashion the tree will not drop leaves as the plant will harden off its leaves and stems and gradually adapt to full sun.
Warning!! Very, very healthy trees can be put out into direct sun. But, many of the leaves will burn and often the whole tree may go into a leaf drop. Replacement new leaves will automatically be sun adapted! This, as with deliberate defoliation, will weaken the tree and so must only be done with extremely healthy trees.
Watering needs will increase once the trees are outside and exposed to higher light, warmer temperatures and increased air movement.
Of course if temperatures remain cool water needs will in fact decrease and create water-logged soil that may promote root rot.
Out of doors wind increases evaporation and watering needs.
Make sure to secure the trees against winds that can dislodge the trees from their pots and stands.
Wire newly repotted trees into their pots to prevent wind and animals from un-planting them.
For most true tropicals re-potting is best done in the heat of summer. Plants will recover most quickly during periods with continually warm night temperatures (70-90F).
Semi-tropicals and temperate or near temperate species will do best when repotted in spring before new growth is extended.
Squirrels and others can and do chew trees. Protect trees from these chewing friends.
Dogs, cats, racoons etc. will be interested in organic fertilizers and can dig up trees looking for treats. Fish derived materials seem the most problematic. In my area bears can be a danger both to trees and to humans and they are attracted to the smells of organic decaying materials.
Close observation helps to detect insect attacks and to allow the earliest treatment possible. Outdoors, insects are usually not a problem but real problems occur when trees are moved back indoors in the fall. But that is another story.
Innocent play can topple and break trees and pots. Frisbees and all manner of flying objects can be quite dangerous to your trees.
Take precautions to hide or secure the trees.
For many indoor growers the outside time each year is the only time that their trees will grow significantly. If indoor conditions are less than ideal little or no growth occurs during the winter. Moving trees outdoors for the summer allows these trees to grow, thicken and get really healthy.
The simple planning discussed above should make the outdoor time more advantageous for the trees and less stressful to you, the owner.