Whoa, finally. Spring has sprung. For short-summered gardeners like me, it is particularly important to get started early. My gardening team and I start many tender annuals indoors. We avoid purchasing seedling trays or pots and try to start most seeds in biodegradable handmade pots. Cardboard tubes, newspapers, grapefruit halves are great options—we use eggshells.
To get crackin’, eat lots of eggs. Prick a small drainage hole in the bottom of the shell with a pin or needle. To remove the contents, create a small opening in the shell—about the size of a dime—with a sharp knife. Reserve the egg contents for cooking my friend Jenny’s Back Pocket Quiche. Carefully pinch the opening until 1/3 of the shell is removed. Wash each eggshell. Surprisingly, it does not take long for hungry, motivated gardeners to have a full carton of clean, empty shells.
Select some seeds. Really, any annuals will do. For a nice selection, see previous post on Spring Planning. My gardening team is partial to fancy pinkish flowers and cherry tomatoes.
With small green fingers and thumbs, fill each eggshell with damp seed-starting mix to about ¼ to ½ in below the shell opening. Place the soil-filled shells into an egg carton. Using tiny finger, create a small indentation in the center of the soil. Follow the instructions on the seed package for proper planting depth. The general rule is to plant three times deeper than the size of the seed. Place a seed or two into the indentation and lightly cover the seed with soil. Use a permanent marker to label each eggshell with seed type. Moisten the soil again gently with a few drops of water. Allow the water to saturate the soil before adding more water. Be careful not to drown them!
There are so many many types of seeds. In a typical dormant seed, like a French bean or sunflower, two future cotyledons occupy most of the interior. The outer covering is called the seed coat. The seed coat is usually hard and protects the softer parts of the seed. There is a tiny hole in the seed coat called the micropyle. When the seed is ready to germinate, water is absorbed into the seed through the micropyle. Rapid growth of the seed’s embryo ruptures the seed coat, allowing the radicle to emerge in search of nutrients. The radicle becomes the root of the plant. The hypocotyl, the space between the radicle and the colyledons, extends and emerges from the soil. The hypocotyl is exposed to sunlight, straightens out and develops into a stem. The cotyledons, two thick, leaf-like thingies, become new green leaves. The tiny plumule rises up between the cotyledons and develops into the plant’s true leaves.
Clearly, seed germination is highly dependent on water. So, to help retain necessary moisture, cover the egg carton lightly with a large transparent plastic container. Monitor your seedlings daily for growth and water needs. They should be kept evenly moist, but not saturated. You should begin to see sprouts in 10 to 14 days, depending on seeds selected. When the seedlings emerge, they will need space for growth, and sunlight for photosynthesis. In general, sunlight on a warm windowsill is best. Keep them in inside until they have 3 to 4 true leaves.
By the time playground weather comes around, your eggshells will house a flock of able-bodied, rosy-cheeked seedlings. Before moving them out of the hen house, take a few weeks to “harden them off”—gradually introduce them to their new growing conditions. Move the “egglings” to a shady spot for increasing amounts of time, several days in a row. Bring them back inside or cover them if temperature looks like it will drop. Progressively increase the amount of time and sunlight they receive outside until they appear ready to venture out on their own. This gives the seedlings a chance to acclimate to sunlight, drying winds and climate changes. On a cloudy day, plant them directly in the ground, crushing the bottom part of the eggshell so the roots can emerge. Water the transplants well, but gently.
Why use eggshells? Eggshells provide good moisture retention for germination, less transplantation shock, a good source of beneficial calcium (especially important for fast-growing tender annuals), and the obvious environmental and monetary advantages.