I reused a container that had potatoes and nasturium in it last year for lettuces this year. I did Jericho Romaine, Red Sails leaf lettuce and a Mesclun mix. They all taste bitter to me. One of the Mesclun lettuces tastes hot. Are my taste buds just not used to home grown lettuce, or could my soil be bad? If so, is there anything I can do? I grew these all from seed and they're beautiful! I'm just not lovin' the taste!
If you're used to bland, grocery store lettuces like iceberg and Boston, dirt-grown lettuce does take getting used to. I speak not as a lettuce grower, but as someone who has been served many many many home grown lettuce salads. Try mixing with other, milder lettuces to get used to the taste, picking the lettuce earlier while it is younger and the flavor is milder, using more dressing, adding tomatoes, sunflower seeds, Parmesan cheese, other stuff. I tell myself that the flavor is the vitamins.
Don't know if it's hot up there but the heat plays a big part in bitterness. If when you cut the lettuce and you see a white milky sap the lettuce is too old and is probably bolting from rapid growth due to the temps. Summer is not a good time for lettuce...Spring and Fall is best when it's cool if it ever does cool off.