Is filtered light ok?
Will sage grow in sunlight filtered through a thin transparent flexible plastic-like screen such as the material which some trash bags are made of? I have some sage growing in my garden and want to plant more. However, some bug eats it when I am not around. I know that I can spray it with a bug killer but I think that building a small green house might be a more permanent solution. I can make a small green house from a wooden frame and walls made of the material described above. I already know that the soil is ok. Will the sage still grow in the filtered light?
Sage is a hardy perennial plant that grows best in full sun. You can use the material above to create a mini greenhouse. Another option is floating row cover. This is a lightweight non woven fabric that offers protection from frost, insects, wildlife, etc. Take a look at our website for ways to use it https://extension.umd.edu/hgic/floating-row-cover
You will have to experiment with the reduced light. This will be common in the fall and winter months. No chemical controls are recommended. Sage can tolerate some insect pests and usually will not kill the plant.
Sage needs a well drained soil especially over the winter months or it will suffer from root rots. http://extension.umd.edu/hgic/topics/sage