1/ adequate water 2/ remineralize the soil (some call adding lime 'sweetening the soil) 3/ check how you're cutting them. i just moved so i can't find my reference book, but, slicing the cucumber from the stem end versus slicing from the blossom end during food prep makes a difference in bitterness, so the old wives tale goes. but i can't remember which is recommended to slice first, blossom end or stem end, so do experiment with that. the deer have eaten our cukes two years in a row. . . .