Soil is turning green in my container garden
About a month ago I set up my first container garden. I've got one tomato plant purchased at about 6" tall and everything else I started by seed: Cucumbers, Thyme, Chives, and Lettuce.
I used the same soil for for everything: generic potting soil in about 3/4 of the containers with seed starting soil in the top 2 or 3 inches.
All containers do have drainage holes. I have fed them once per week (per box instructions) with Miracle Gro Tomato Food. It states that it can be used for all vegetables so I've used it on everything.
Now, 3 maybe 4 weeks later everything but the lettuce has a very fine layer of green on it. It's a very deep green. I mixed up the soil around the tomato plant about 3 days ago when I first noticed it and so far the green has not come back yet. I haven't touched the soil for everything else since the sprouts are all still very small and I didn't want to damage them.
Does anyone know what this green stuff is? Is it harmful to the plants?