The tulip festival website mentions that they are:
Open Every Day April 1-30 9 a.m. to 5 p.m.
Is it possible to visit the tulip fields earlier than that? I would like to take some nice photos, as well as try and beat the weekend crowds.
The tulip fields come up to and are clearly visible from the sides of many ordinary roads through the farmland of the Skagit Valley. These roads are open 24/7 and you can drive along them, park on the shoulder, and take beautiful pictures of the tulips at whatever hour of the day you like. The "opening hours" listed on the website are for the administrative offices, which are of quite limited relevance to tourists.
Source: I used to live in the Skagit Valley.