I have live butter lettuce that I bought from the grocery store that I planted. It tasted fine before I planted it. Now that it has been growing for a few weeks it tastes bitter. Anything u can do?

Welcome to NGA, @SuzieEss !

Your lettuce plant might just be past it's prime; lettuce does tend to get bitter as the plants age, particularly in hot weather.

Yes, lettuce has a somewhat short window for which to grow it. Afterwards it bolts, trying to go to seed or actually going to seed. Tastes bitter then.