Keep vegetables submerged below the brine at all times

The single most important safety rule: everything being fermented must stay below the liquid surface. Vegetables exposed to air above the brine are where mold grows. Use a glass weight, a small plate, a zip-lock bag filled with brine, or a cabbage leaf pressed on top.

Why It Works

Lactobacillus bacteria thrive in anaerobic (no oxygen) conditions. Mold and harmful bacteria require oxygen to grow. As long as food stays submerged in the acidic brine, the environment is inhospitable to dangerous organisms.

Tips

• Check daily during the first week and push down any pieces that float up
• Glass fermentation weights ($8-12) are the most reliable hands-off solution
• A zip-lock bag filled with brine placed on top works as an improvised weight
• If a piece of vegetable floats above the brine and develops mold, remove the moldy piece — the submerged portion is usually fine