The Surprising Reason You Should Never Start Seeds In Eggshells

In an effort to be more environmentally conscious and sustainable, gardeners around the world have come up with lots of clever ways to reuse things in the garden that would have otherwise ended up in a landfill. While this is commendable, there are surprising reasons why not all of these practices are actually beneficial, and some could even be detrimental to the healthy growth of the plants you're going to lovingly care for. One common idea that you may have come across is to start your seeds in eggshells. 

On the surface, this kind of makes sense because eggshells are organic, so we would expect them to decompose in the soil. But if you've ever put eggshells in your compost (and you should do this with one proviso), you'll most likely find that when you're collecting it to add to your garden, the shells are still intact. That's because they take absolutely ages to break down, by which time your little seedlings will have died because their tiny roots simply couldn't break through those immensely tough shells. Even though there are plenty of benefits of starting seeds instead of buying plants, you don't want your efforts to go to waste, which is why you should avoid starting them in eggshells.

Now that you know your seedlings are not going to survive if you plant them straight into the garden with the shells intact, there are a couple of things you can do. You could just gently remove the plants from the shells, taking care not to damage the roots, and then plant them straight into the garden. Alternatively, you can follow the instructions on how to use eggshells as seed starters, and crack the shells to ensure there are plenty of spaces for the roots to come through and travel into the soil below. 

You also shouldn't expect the calcium in the shells to nutrify the soil, because this can take years too. The calcium carbonate which gives the shells their tough exterior can be released and made available to the plants only when the shells have decomposed.

What about adding those shells to your compost? Eggshells are certainly compostable, but you need to break them up first. The ideal method is to grind them into a fine powder with something like a coffee grinder. In a study conducted by the Alabama Cooperative Extension, the researchers found that finely ground eggshells were as good as adding pure calcium to the soil, and even better than adding agricultural lime. On the other hand, coarsely ground eggshells provided very little benefit at all. Finally, as an alternative, you can simply reuse empty food containers as perfect DIY seed starters for a different type of sustainable solution.