Antelope State Poppy Reserve comes alive each spring with the seasonal surprises of the Mojave Desert Grassland habitat. The duration and intensity of colors and scents vary from year to year. Although the wildflower season generally lasts from as early as mid-February through mid-May, the park is open year-round from sunrise to sunset. Fall is also a pleasant time to visit, as the days are normally warm with milder winds. Antelope Valley.