I grow catnip.When we get real hot,I DO have to water it more.its leaves will go limp durring the day,but when evening comes will perk back up.we've been hot the last 3 days (triple digit heat index with temps in upper 90s)The plant
growing in more shaded area does fine& the plant my cat plays in its roots are shaded.(kinda mixed in with cannas)maybe try mulching the plant some it will help hold in the moisture longer.