Tithonia Also called mexican sunflower (Tithonia) Three- to 4-inch, sunflower-like blossoms on 4-foot-tall plants. Orange-red flowers with light centers. Soil and Light Drought resistant. All soil types. Full sun. Planting Sow 4 to 6 weeks early inside, or outside after frost danger. Comments Use bushy plants as temporary hedges. Grows quickly in hot weather.