Ah, the banana. It's the simplest of snacks with its self-contained, eco-friendly natural packaging. But timing the ripening of this cheery fruit requires some planning that most every other item in the produce department doesn't need.

Here's why: Bananas are rarely perfectly ripe when you buy them at the supermarket. This is not an accident. Unlike many fruits and vegetables, bananas actually continue to ripen after picking, so a banana that's fresh before it even reaches the grocery store would become overripe much too quickly for most shoppers' tastes.

But what do you do with that rock-hard fruit if you want a perfectly ripe banana right now? And what if you're craving banana muffins, but the bananas at the store still light yellow, or edged with green? Here are some tricks for ripening your bananas faster than nature intended.

Have a Day or More? Try The Paper Bag Technique

As bananas ripen naturally, the peels give off ethylene gas. The higher the concentration of ethylene in the air surrounding the banana, the faster it will ripen. Commercial banana producers use ethylene gas to control ripening in order to send bananas to retailers at specific stages of ripeness.

You can take advantage of ethylene's ripening properties at home by putting your banana into a closed paper bag; the paper will trap ethylene while letting in enough oxygen to help move the process along. For even faster ripening, add an apple, pear, apricot, or avocado—they also release ethylene. However, do not to keep the bananas in plastic bag, which doesn't let in enough oxygen and can actually inhibit ripening. That's why the bananas at your store are often bagged in plastic, to keep them from ripening too soon.

Depending on how under-ripe your bananas were to start with, paper-bag ripening will take 1-3 days; putting the bag on top of your fridge or another warm location can speed it up even more. Check them daily, and when the bananas are firm and bright yellow with no trace of green, they're good for eating raw. Once brown spots start to appear, you can use them for baking.

Have a Few Hours? Bake Them in the Oven

What if you want to make banana bread today, not in two or three days? To speed-ripen bananas in the oven, preheat the oven to 300 degrees and line a baking sheet with silicone or parchment (the bananas may leak a little during baking). Place unpeeled bananas on the baking sheet with some space between them, and bake for about half an hour, checking every 15 minutes to see if they're soft enough. The more under-ripe they are to start with, the longer it will take to ripen them. The peels will turn black, and the fruit will be soft—too mushy for eating raw, but great for baking. Let them cool before handling.

Have Just a Few Minutes? Pop Them in the Microwave

You can zap firm yellow bananas to soft ripeness in just a few minutes. Poke unpeeled bananas all over with a fork or knife, then put them on a paper towel or plate and microwave on high for 30 seconds at a time, repeating until they're as soft as you want them. They won't be quite as sweet as the oven-ripened versions, but they'll be mashable for your muffins and quick breads.

Now that your bananas are ripe and ready, try one of these recipes: