Cornell University recommends mixing one part sugar with four parts water to make a sugar solution for hummingbirds. A higher sugar content of one part sugar in three parts water could help hummingbirds obtain more energy during cold, rainy or foggy conditions.
According to the University of Kentucky, high sugar content could attract unwanted insects such as butterflies and bees. Most flowers that these insects feed on have an average nectar content of 42 percent.
The University of Kentucky recommends adding more water to the hummingbird sugar solution if it is too sweet. Change the solution so that it contains one part sugar in five parts water.