Answer: Celery does best in areas with long, moist growing seasons and relatively cool summer temperatures--65 to 75F daytime, 60 to 70 at night. Some of the red varieties actually need quite cool weather--even a frost--to develop their red color. It is true, however, that young plants exposed to temperatures in the 40's for more than a week straight will tend to bolt prematurely.
I'm not sure what the difference with the commercial celery is. Celery does prefer rich soil with lots of organic matter and plenty of potassium. Prolonged dry periods can lead to bitter, tough stalks. Perhaps this was the problem with your store-bought produce.
Congratulations on your celery success! Isn't it nice to prove the "experts" wrong sometimes?
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