The paper towel method (also known as the baggie method) is helpful for germinating seeds that require constant heat and moisture, such as hot peppers.
While our first instinct is to bury seeds in soil to get them to sprout, certain seeds actually need light to germinate. This is a common reason some seeds fail to germinate—not because they’re old or need heat, but because they require exposure to light.
The general rule of thumb is to plant a seed at a depth of two times the width (or diameter) of the seed.
If you’re finding that your seeds are slow to sprout, the reason may be inconsistent moisture. Fortunately, the solution is as easy as dropping a handful of seeds in a cup of water for a few hours to soften their seed coats and move them further along in the germination process.
To do so, gently scrape off a tiny part of the seed coat with a razor blade or nail clippers, or lightly rub it with a nail file or sandpaper. Just don’t overdo it, or you risk damaging the embryo inside if you go too deep or remove too much of the seed coat.