Guest Author - Haidy Ear-Dupuy
Sunlight in the summer
Unlike the sun in the winter, the summer sun can be hotter and can often damage the leaves of your orchids. If you are to move your orchids outside for the summer, make sure to put them in the shades first and slowly move them into partial shade after a period of around one week. For phalaenopsis, it is best to keep them in filtered sunlight rather than direct sunlight.
If growing them indoor, the same sunny location near the window in the winter can be too hot for your orchids in the summer. If you find that your orchidsí leaves begin to turn yellow in spots and that they feel hot to the touch, you can try moving your orchids away from the window, farther from the source of light to reduce the heat.
For orchids outdoors, you can water more if the heat is intense and your area does not have rain,--twice a week if your plant is in a porous pot with large potting medium. For those in more humid climate the orchids can capture moisture from the air and you can water less, once a week should be sufficient. For vandas orchids and cattleyas, they can take more sun exposure than the phalaenopsis.
If you are to hang them in rows, you can put the vandas and cattleyas in the front, towards more sunlight and the phalaenopsis and dendrobium towards the back. Generally, the larger the surface area of the leaves the more sensitive it is to sunlight, you can put the orchids with the smaller leaves closer to the sun.
For orchids indoor, make sure that you feed them and water them well at each session, usually about once a week and pay attention to the color of the leaves. As they get more sunlight the leaves tend to turn lighter green. Darker green leaves are generally the plants that do not have as much exposure to the sun.
Pay careful attention to your orchids and make sure that the blemishes on the leaves are not from virus infection. Generally, a burnt leaf would not spread while a leaf infected with pests or other plant virus tends to spread on multiple leaves and in multiple patches, even on leaves that are vertical. The burnt leaf tends to be the horizontal ones that gets the most heat from the sun.