If over-watered, the plants may develop large leaves and lots of green growth at the expense of flower buds. For more blooms, it is recommended to water deeply, but less often.
Try to plant in a location that enjoys partial sun and remember to water moderately. Ideally plant in loamy and potting mix soil and try to keep the ph of your soil between the range of 6.0 and 8.0 as Endless Summer likes to be in weakly acidic soil to weakly alkaline soil.