I love to recycle and reuse materials I have on hand, so I was especially excited to use egg cartons to grow vegetable seedlings under my grow lights. Thankfully, we use a fair number of eggs in my family, so saving up 6-8 cartons did not take too long.
The first step, of course, is to save your cardboard egg cartons. If you don’t eat eggs, then save other containers you think will work for seedlings. As you can see from the photo, the egg cartons have the advantage of offering a good amount of space to grow without taking up too much space under the grow lights. My neighbor used a plastic cupcake box from the bakery; it came with a lid, which she found useful for keeping seedlings warm. I’ve also used the bottom half of a milk jug to start seeds.
Before using the cartons, I sprouted the vegetable seedlings in plastic sandwich bags. I splashed some water on a paper towel, folded it up, and then placed seeds on it. I then folded the paper towel again so that the moisture would surround the seeds. Once that was done, I slid the paper towel into each plastic baggie and sealed it shut. Most importantly, I labeled everything. (Oh, that is so important.) The weather was still fairly chilly when I did this, so I placed the sprouts-to-be under the grow lights to get a bit of warmth. Other people have had success placing their baggies of seedlings on top of the refrigerator or near a heating source (be careful not to set things on fire, of course!).
Once the seeds had sprouted–this is an excellent way to teach children about how seeds work, by the way!–I filled each space in the egg cartons with seed starting mix. (Please see the photo.) You definitely want to use seed starting mix as opposed to soil from your garden, because the mix will be lighter and allow seedlings to get the air and water they need. Soil from the garden often proves too compacted to allow seeds to grow well. Seed starting mix also contains valuable and necessary nutrients for the tender seeds.
At first, I poured water into the egg cartons cups with a tiny pitcher, but that moved the soil around too much. I found that a spray bottle moistened the soil without disturbing the seeds. Plus, the spray bottle holds more water, so I don’t have to troop to the sink to refill as often. I aim for efficiency when possible.
I hope this post helps you when it comes time to start your own seeds. If you have tips to share, please feel welcome to add them in the comments.