I did some thing similar I love starting from seed the entire process is amazing now my garden pretty much self sows for the past 5 years I've had sunflowers, tomatoes and morning glory without doing anything. Here is a container my husband made for me getting ready to bloom I have everything in there except the kitchen sink it's all my compost with renegade seeds
I don't have the heart to sterilize it so every year it's something different.