Celery leaves tend to be more bitter than the stalks in general, but bitterness can be intensified by all the conditions you mentioned, including high temperatures, inconsistent moisture, and poor soil. The bitter taste also gets stronger as the plant matures, so consider harvesting the shoots when they’re younger. Also look into blanching your celery before harvest—this can reduce bitterness, too. To blanch, loosely wrap the celery stalks with paper (newspaper works well) 2 to 3 weeks prior to harvesting. The stalks will lose their green color, but should also not be as bitter.
Celery leaves tend to be more bitter than the stalks in general, but bitterness can be intensified by all the conditions you mentioned, including high temperatures, inconsistent moisture, and poor soil. The bitter taste also gets stronger as the plant matures, so consider harvesting the shoots when they’re younger. Also look into blanching your celery before harvest—this can reduce bitterness, too. To blanch, loosely wrap the celery stalks with paper (newspaper works well) 2 to 3 weeks prior to harvesting. The stalks will lose their green color, but should also not be as bitter.