Fill a large pot with the pickling cucumbers and cover them with ice cubes. Allow them to sit for at least 2 hours, or up to 8 hours, to enhance their crispness. Once the time has elapsed, drain the cucumbers thoroughly and pat them dry with a clean towel.

In a large saucepan, combine water, distilled vinegar, sugar, pickling salt, and the pickling spice wrapped in cheesecloth. Bring the mixture to a rolling boil, then reduce the heat and let it simmer gently for 15 minutes, allowing the flavors to infuse.

Meanwhile, sterilize the canning jars and their lids by submerging them in boiling water for at least 5 minutes. Once sanitized, carefully pack the cucumbers into the hot jars, ensuring they reach about ½ inch from the top. Place one head of fresh dill and one clove of garlic into each jar.

Pour the hot pickling liquid into each jar, filling them up to ¼ inch from the rim. Wipe the rims with a damp paper towel to remove any residue. Secure the lids and screw the rings on firmly, ensuring a tight seal.

Position a canning rack at the bottom of a large stockpot and fill it halfway with water. Bring the water to a boil over high heat, then carefully lower the filled jars into the pot, ensuring a 2-inch gap between them. If needed, add more boiling water until it rises at least 1 inch above the jar tops. Bring the water back to a vigorous boil, cover the pot, and process the jars for 5 minutes.

Using a jar lifter, carefully remove the processed jars and place them on a cloth-covered or wooden surface, ensuring they are spaced a few inches apart. Allow them to cool completely. Once cooled, press the center of each lid—if properly sealed, the lid should not flex up or down. If any jars have not sealed correctly, refrigerate them and consume within two weeks.

Store the sealed jars in a cool, dark location for optimal preservation. For the best flavor, let the pickles develop for at least one week before opening.