Why is celery sometimes bitter?

Here are some tidbits I found:

"In addition, evaluate the celery to ensure that it does not have a seedstem--the presence of a round stem in the place of the smaller tender stalks that should reside in the center of the celery. Celery with seedstems are often more bitter in flavor."

"Improper environmental conditions, primarily high temperatures at maturity along with stress conditions such as drought or low fertility can cause off-flavored celery. For maximum quality celery must be grown under suitable environmental conditions and a constant level of available moisture."

i moved from tennessee to pennsylvania about 8 years ago. the celery in tennessee was always so refreshing i would snack on it nightly to keep my calorie count down. when i moved here i was so disappointed--the celery is bitter year-round. i'm commenting because i bought a nice bunch of celery 2 days ago and when i took a bite last night, it was so bitter i threw it out. i wish i knew if there was anywhere to get celery around here that is edible.

Sorry never had this happen before.

Maybe the celery was abit old.

Or Maybe it was abit young & hadnt matured

nope i have never had bitter celery before