What do I do to enhance the red color. I have had several plants in a moist sunny area between my driveway and several walks for about 10 years. Minimal red color is present if at all. The plants are healthy and spread rapidly as expected. email@example.com or 201 919 4166. I live in NW NJ zone 6.
The color is usually more intense in hot weather and with more sun. Another possibility is that some of your plants have reverted to a non-variegated, all-green form and are taking over. This can happen because most variegated plant varieties (those with multicolored leaves) are mutants that are less vigorous than the all-green form of the same species. This article explains why it happens:
If you still have any plants that have the red color, prune out the green plants around them to encourage the multicolored form to grow.