Garlic and Dill Lacto-Fermented Pickles

Ingredients

• 1 gallon spring water
• 0.75 cup sea salt
• 5 pounds fresh pickling cucumbers
• 3 (2 inch) pieces peeled horseradish root
• 6 medium heads fresh dill
• 2 large onions, cut into rings
• 1 head garlic, cloves separated and peeled
• 5 tablespoons whole black peppercorns
• 3 tablespoons whole mustard seeds
• 2 tablespoons red pepper flakes
• 6 large bay leaves
• 3 cups washed mustard greens, or as needed