QUESTION: I want to start lettuce from seeds. What’s the best way to start the seeds? What happens if you plant lettuce seeds too deep? -Kimmie R.
ANSWER: Seeds that are planted too deep in the soil may grow into weak, feeble seedlings or fail to germinate at all. If it’s been buried too far under the surface of the soil, the seed may not get the light it requires to sprout. If Romaine lettuce seeds that are planted too deep manage to sprout, the lettuce may fail to form a heart. Getting the planting depth right is especially important with very small seeds like those for lettuce plants.
A rule of thumb you can use if your seeds didn’t come with instructions—you can calculate the appropriate planting depth for a particular seed by multiplying its diameter measurement by three. Depending on the variety of lettuce you are planting, seeds should be buried at a range between an eighth of an inch and half an inch deep.
Most lettuce seeds are so tiny that they barely need to be covered at all: just a light dusting of soil over the lettuce seeds will suffice. In fact, some gardeners recommend not actually burying your lettuce seeds at all, since they’re so tiny. Instead, you can sprinkle the seeds on the surface of the soil, gently pressing them with your hand so they’re securely situated. Then mist the seeds to moisten the soil.