Harvest cucumbers for pickling when the fruits are 4 to 5 inches long. With some pickling cultivars, it may be necessary to pick daily to prevent them from becoming overgrown. If just one cucumber is allowed to fully mature, the entire vine will quit producing.
If you plan to use them fresh, wait until they're 7 to 8 inches long. Use a sharp knife or pair of scissors when harvesting, and leave a short length of stem on each fruit.
Cucumbers can develop a bitter taste when soil moisture is inconsistent so keep the soil around the plants evenly moist. Most of the bitterness is concentrated in the ends of the fruits, so cut them off prior to slicing the fruits. Cucumbers will keep for 1-2 weeks in the refrigerator.