Soil is turning green in my container garden

AngZMay 8, 2013

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?

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edweather(Zone 5a/b Central NY)

You say 'potting soil.' Is that what it was? It's best to use a soilless potting mix. That's what might be making it green. Sounds like some kind of algae.

    Bookmark   May 8, 2013 at 1:49PM
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The seed starting mix didn't appear to be soil. I think it was more pete moss. The generic stuff was definitely at least part soil. It was nearly black and had a funny almost chemical smell to it. I have zero experience with soils so I did not know if that was normal. If I remember right, the bag was labeled as "General Potting Soil" and below that it said it was Topsoil. Which did confuse me, as I thought there was a difference between the two...

    Bookmark   May 8, 2013 at 1:56PM
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edweather(Zone 5a/b Central NY)

That's probably the problem. The bag said Potting Soil and Topsoil, which means 'dirt.' I'm almost sure that's what is turning green with algae. If it's not too late maybe you could repot using a potting 'mix.'

    Bookmark   May 8, 2013 at 2:04PM
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I'll give it a shot. I suspect I'll just start the herbs and cucumbers from scratch again. I just hope I haven't done any damage to my tomato plant.

Thanks so much for your help!

    Bookmark   May 8, 2013 at 2:10PM
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