Here's another reason to choose natural charcoal over charcoal briquettes, which have chemical additives like lighter fluid embedded inside: You can use them after you've grilled up dinner. Natural, additive-free charcoal has potash, a nutrient that plants love. After the charcoal has cooled off enough (about 48 hours after use), you can take the ash and spread it around the garden as a natural fertilizer. You can also mix it in your backyard compost bin to help increase the carbon content and create a richer compost. If you have larger charcoal pieces that didn't burn down into ash, mix them in with orchids to help them thrive, too.