Not really. Actually, there are not research papers or medical textbook shows that looking at greenery will improve eyesight. Greenery does not have any magical sight-improving qualities nor can any color in the spectrum improve your eyesight one bit.
But why so many people think that greenery can improve eyesight, the reason is that greenery is usually at a distance. A grass patch, a group of trees is usually at least a few meters away from us, if not more. This means the eye is focusing at an object far away when we look at greenery. The eye muscles have to change the shape of the natural lens of the eye in order to help it focus for near. The medical term for this muscle action is called accommodation. The more the eye accommodates, i.e. the more near work we do, the more the short-sightedness will increase.
These muscles are relaxed when we look far. This is why we always hear about good eye care habits that include reducing time spent reading, writing and using computers/hand-held devices; and to look far away after every half hour of reading/writing. So, while it is not likely that looking at greenery will help "improve" our vision, it will do us some good for us to look at greenery, or more accurately, looking at objects that are far away as it will help us prevent an increase in short-sightedness.
It is said that looking at the green plants will be helpful for your eyes. It is reasonable because it will help you reduce visual fatigue. But looking at the green plants will not cure your short sighted eyes. Instead, it will improve your eyesight. You'd better choose some time to do such exercise.
Yes, green can improve eyesight.
Absorption and reflection of light is varied with different colors. In which, the reflectivity of green is the lowest. Modern science has proved that green plants can decrease the irritation of eyes and can absorb drastically UV.
And the following tips are also useful:
1. Focus far and close. First look at a green tree or grassland 10 meter away for 25 seconds, then lift your hand up, 30cm from your eyes and slightly above eyes, look at your hand carefully for 5 seconds. Away, close... practice for 10 minutes every day.
2. Make eye exercise. Massage around eyes, have your eyes relaxed.
3. Close eyes and roll eye balls. Exercise eye muscles.
4. Some foods are good for eyes, like medlar, chrysanthemums, carrot.
Nope, but it could help you to reduce eyestrain. We always hear people say green makes eyes better, that is to say, this color could make you feel more relaxed somehow, especially after you starring a computer or TV screen for a prolonged period. However, it could make your muscle of eyes relax instead of improve eyesight. Normally you need to look at natural green things, as you said, green trees far from you could relax your eyes. However, it is always harmful to stare at one object for a long time without moving your eyeball, no matter what the color of it is.