How to Prevent Blossom End Rot Using Eggshell Seed Starters

Each spring I start seeds inside on the windowsill to get a jump on the growing season. It's getting to be that time of year again, so I've been saving my eggshells to make these cute seed starter cups.

Functional and practical, they are not only a great way to recycle your eggshells, they also help prevent a fairly common plant disorder called 'blossom end rot'.

What is Blossom End Rot?

Blossom end rot occurs when vegetables can't absorb enough calcium from the soil and the flesh on the blossom end (not the vine end) of the vegetable breaks down, turns black and dries up.

By planting your seeds in eggshells, the disorder can be avoided because as the eggshells breaks down, it releases calcium into the soil. You can purchase a commercial product called Rot-Stop to spray on your vegetables, but I would rather let the eggshells prevent blossom end rot naturally.

All plants need calcium and can benefit from being planted in eggshell cups, but certain crops are more susceptible to blossom end rot including tomatoes, broccoli, Brussels sprouts, carrots, celery, squash, lettuce, peppers, melons, and eggplant.

Making Eggshell Seed Cups

To make your starters, crack your eggs, leaving about 2/3 of the shell intact.  Rinse out the egg reside.

Poke a small hole in the bottom for drainage with a pin, then scoop a bit of seed starting soil into each shell (mix some coffee grounds in to the soil for an additional nutrition boost). Press a few seeds into each shell and loosely cover with a bit more soil.

Mist with water and set your shells in the egg carton on the windowsill or in a warm spot in your house. Cover them with plastic wrap to retain more of the moisture. Keep the soil moist and you should see sprouts in no time!

Planting your Seedlings

Remove the plastic wrap once the seeds have sprouted.

When you are ready to transplant your seedlings, crush the shell a bit with your fingers or remove the bottom part to allow the plant roots to escape, and plant the seedling, shell and all, in the ground.

If your seedling outgrows the shell before it's time to go outside, you can plant the shell cup in a larger pot or container until it can be moved outside.

Watch my step-by-step video tutorial.

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  1. This is the first I've heard about Seed of the Month club. I should join!

  2. This is a great idea for shells!

  3. Love it! I always have a problem after my plants blossom. Not this year though - now to start saving my eggshells!

  4. Amanda ( The Kitcheneer)March 15, 2015 at 4:02 PM

    I usually start my seeds inside, but in those mini planters. I will have to try using eggshells this year! Thanks for the tutorial!

  5. Interesting! I would like to grow plants for my own mini garden, this is very neat! Can you use store eggs? (I know it's a crime to buy store eggs when you have hens, but mine aren't laying much yet!) ;)

  6. If you put a tomato plant in the grown can you sprinkle the crushed egg shells around each plant to help the blossom end rot?

  7. Hi Nanma, Yes, you can put crushed eggshells around each plant for blossom end rot. I have done this and it works very well, just work it in a little around each plant and water. I have done this after I spotted end rot on a few tomatoes and this prevented the remaining ones from developing it. It's probably a good idea to do it early on (when the plant first starts to set fruit) to avoid it altogether. That's what I'll be doing from now on! I also reapplied the eggshells about halfway through fruit development. Hope this helps!

  8. I didn't wash out my egg shells before adding the soil and seeds. Will this cause a problem? they are starting to smell a bit.