This is a perfect idea for people who live in very small spaces but still want to grow a little food. And we do mean "little". Microgreens are the stage between sprouts and baby greens - basically, they are seedlings.
You can grow and harvest small batches of microgreens on your windowsill for fresh picked greens throughout the long winter months.
Microgreens are tender and tangy lettuce and mustard greens that are usually harvested when they are barely a few weeks old. They are basically at the growth stage between sprouts and baby greens. This short growth span that makes microgreens possible to produce on even the darkest windowsills through the dingiest months of the year. And since the plants only need to be kept alive for a few weeks even the most beginner seed starter is pretty much guaranteed success.
As you can see, you can plant microgreens in just about anything. While shells are both beautiful and forgiving, smaller "planters" like walnut shells and thimbles may need to be watered multiple times a day.
One of the easiest and most cost effective containers to start microgreens in are recycled plastic takeaway containers and clamshell packaging. To prepare, simply punch 5 drainage holes and fill the container with well-moistened container mix or seed-starting mix to within an inch or so from the top. Evenly distribute a thin layer of seeds, sprinkling them over the soil surface with about 1/4″ of space between them. Cover the seeds with a thin layer of soil, about 1/8″ deep and water well to get them germinating. Place it with the lid of the clamshell underneath as a drip tray in the sunniest window you’ve got or under a grow light. I have positioned microgreens in various locations and even in partially shaded north light they still come up. That said, the more light and gentle warmth they get the faster they will grow. (Be careful not to cook them or let them dry out.)
Keep the soil moist but not soaking wet. Microgreens can be harvested in about 2 weeks depending on how large you want to grow them. I generally let mine grow until they have their first set of “true leaves”. The first leaves you see are called “seed leaves” since they are actually a part of the seed. “true leaves” are the second set to appear and look very different than the seed leaves.
To harvest them, you can either cut them off just above the soil or gently pull them out of the soil and cut off the roots. I find this is easier then cutting them first and then trying to pull the roots out so that I can reuse the soil. As long as there were no problems with disease or pests you can reuse the pot and soil. Just add a little liquid kelp fertilizer and till the remaining soil with a fork. and you are ready to plant your next crop. Remember the nutrients in your plants come from the soil so if your soil is depleted you will not get a healthy nutritious crop.