My friend and I have been growing green onions in planters in our school classroom for a research project. We had planted them in Miracle-Gro soil, water them every day (except for weekends but we give them extra water on Friday), and placed them next to a large window. We had grown them for about 6-7 weeks when we came back from a weekend and noticed that they were definitely dead or dying. Personally, I garden at home but I’ve never dealt with green onions or container plants.
We did some research as to what might help the plants grow better when we plant them again but we haven’t been able to find anything that directly relates to our problem. We had our plants set-up in two separate containers, each with 4-5 holes on the bottom, and sitting in larger black containers. They were planted about an inch or two of soil and we put several seeds in each of the holes we made. The plants took about a week to germinate and then started growing well, with them all growing upwards. After a few more weeks the green onions stopped getting any wider and became limp. We pulled a couple out to discover that they had no, or very thin, roots.
What are we doing wrong? We were wondering if they needed more sunlight or hotter temperatures? Or if there was a different soil or a fertilizer we should use? For our project, we won’t need to actually harvest the green onions, but we will need them to be healthy and growing as we expose them to different substances. The photos I attached show the plants when they were growing well, they’ve since become limp and are laying down across the soil.
Onion seedlings have very small and shallow roots. They need to be monitored for moisture quite closely. Also if they are over watered with poor drainage the seedlings may perish.
I suggest sowing the seeds quite densely and then thinning them out as they mature.
They will need good light once they have sprouted.
6 to 8 hours of sunlight. You may want to add a grow light for enough light.