Hibiscus plants require consistently moist soil to produce the most blooms. Water hibiscus plants at least once a day, except on rainy days, making certain to saturate the soil around the root ball completely. Increase watering to twice or three times a day when temperatures exceed 80 degrees Fahrenheit.
To help perennial hibiscus plants survive the winter months, be sure to water them well before the cold temperatures arrive to keep the roots and stems strong. While all hibiscus plants love water, some cultivars, such as Scarlet Swamp and Confederate Rose, prefer consistently damp, swampy soil and even tolerate some flooding.