Certified GKH Gardening Expert
Pink is normally a sign of overwatering. It may also have some yelow color. It can also signal a lack of nutrients, change in temperature (generally cooler), or a chemical reaction to sunlight (not as common).
If the soil is wet around the plants, back off on watering and allow them to dry out some. You may also want to have the soil tested to see if there is anything missing and then correct it. Not much you can do if it's caused from a sudden shift in the weather, though they should recover on their own if this is the case.