When we're talking about hard, or semi-hard, cheeses, we're talking about cheeses that are firm to the touch, have a low moisture content, and hold their shape when brought to room temperature. Think cheddar, not Camembert. And the good news for those who are trying to keep hard cheeses mold-free and tasting good for as long as possible is that these cheeses are pretty robust. According to the experts at the California Milk Advisory Board, the shelf-life of hard cheeses like Parmesan or Gouda is four to eight weeks, but that's only if you can learn how store hard cheese correctly.
Since these cheeses are fairly robust, there's not much you have to do to store hard cheese properly. The cheese experts at the Wisconsin Milk Marketing Board recommend that you refrigerate your cheese, between 34°F and 38°F, and keep it away from other foods that smell strongly because "cheese easily absorbs other flavors." You also want to keep your cheese covered, because exposure to air will dry out the cheese and make it look brittle.
But you also want to make sure your cheese has a chance to breathe, especially if you're trying to keep it from getting moldy. That's because a too-tight wrap will keep in the moisture and restrict oxygen, which "encourages the growth of bacteria and molds, not always the cheese’s own," writes Harold McGee in On Food and Cooking: The Science and Lore of the Kitchen.
If you plan on eating that block of Monterey Jack in a day or two, you can get away with keeping it wrapped up in plastic wrap. After all, that's how most cheese are sold in the supermarket. "If you do not plan to consume these cheeses within a few days after its original package is first opened," and are looking to extend the shelf life of hard cheese, note the experts from the CMAB, "consider removing their original plastic wrap and re-wrapping in parchment or wax paper, which allows the cheese to breathe." They then recommending putting that re-wrapped cheese in a "covered plastic container or an open resealable-type food storage bag," and opening the bag or container a couple of time a week to let in fresh air.
What do you do if hard cheese gets moldy? Well, if your block of cheese is big enough, and the mold is only on the surface of the cheese, you can probably get away with slicing off the moldy bit before eating. According to food safety specialists from Clemson University, "Remove at least one-inch around and below the mold spot," adding that you should, "Keep the knife out of the mold itself so it will not contaminate other parts of the cheese."
Now go forth, and enjoy that cheddar without worrying about mold.