The good news is that hardy hibiscus will survive outdoors in Zones 4-9. The bad news is that for the plant to thrive and bloom well, it needs a spot where it receives full sun. A location that sees at least 6-8 hours of direct sunlight a day is best. If you situate your hardy hibiscus where it gets only half a day of sun, it may produce few blooms, if any (and the blooms will appear later in the season). In addition to full sun, the plant prefers rich, well-drained soil. Because your garden has sandy soil, you'll want to amend the planting hole liberally with compost or well-rotted manure.