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About this product:
Rating of 4.2 from over 590 customer reviews.
About this store:
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Styrofoam is environmentally harmful in a sense, but probably not as much as repeatedly buying bleached wood pulp that is trucked around every year. You'd certainly be releasing more CO2 emissions that way. Nevermind that unlined paper cups mold and begin to disintegrate after watering or that waxed paper cups are lined with petroleum distillate.
You raise a valid concern, but unfortunately you tried to answer it with likely little basis in valid evidence. Styrofoam is a simple and very stable molecule. There is no strong indications that growing in Styrofoam cups at the seedling stage has significant effects on absorption of toxins into fruits and vegetables that come months after transplanting and have roots mainly in soil that never contacted Styrofoam. Then you'd have to look at whether watering washes away the theoretical leaching you are concerned about.
Like I said, I think your concern is valid, but where is the evidence of this measured contamination in growing seedlings in well drained potting soil in Styrofoam cups? Some studies show minor effects, and some even show beneficial effects, but in both cases, the researchers are purposely contaminating the soil with levels of polystyrene microplastics that would not occur from starting plants indoors for a few weeks. Even storing food in direct contact with polystyrene is considered safe so long as it isn't heated.
"Research suggests that polystyrene microplastics can sometimes stimulate plant growth, particularly root elongation, potentially by increasing carbon and nitrogen levels in the plants."
I buy a 20 pack of 16oz Styrofoam cups and a 14 pack of 20oz Styrofoam cups from Walmart for a couple dollars.
I put herbs in the 16oz. cups. I put big plant mass vegetable on the 20oz. cups.
Should be able to get at least 10 years of crops out of them, and protected from sun in the garage, I wouldn't be surprized if they last decades. Styrofoam is also an excellent insulator for the roots from rapid temperature swings. On year five now.
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Terrible reading comprehension. I offered no advice in that comment. I just summarized available evidence and requested more evidence if someone found it.
I've tried similar systems. They don't really work well.
Now after close to a decade of dedicated seedling production - I've settled on a 2-phase system.
1 - I start seedings in an Aerogarden seedling starting tray - where I let them sprout, and grow to about 4-6" tall (for tomatoes)
2 - I move them into round ~4" pots, with these carrying trays: https://www.greenhousemegastore.c...3417606343
The system works well, and if you invest in the pots and trays, they should last you for a decade or more.
I use the Aerogarden as well for seed starting. I did a test this year with Lavender. I put most of the seeds in the Aerogarden and some in one of those Jiffy seed starter trays that holds like 10 plants. The ones started in the Aerogarden are 3 times the size of the plants in the Jiffy seed starting tray. 100% germination rate for both methods. The only thing I don't like about using the Aerogarden is that you have to pot them up so you are doing double the work.
Our community has rated this post as helpful. If you agree, why not thank rayoroa
I do soil blocking. As other people have said: you really do need a specific soil blocking mix for these things. you can't just put seed starter in or whatever your normal mix is. It's totally different
1) air hits all sides of the block and dries out fast without proper moisture control
2) the blocks will fall apart without proper structural mix
If you decide to do this: google Elliot Coleman seed block mix. That mix is tried and true way of doing soil blocks.
Once you perfect this method, it's much better than cups. You can do a lot of seedling starts much quicker and the transplants are much healthier. What happens is the roots will hit the edge of the soil block where the soil meets the air and then the root stops and the plant will shoot out a new root. This is called air pruning.
What you end up with is a much healthier plant with a great root system. Using this method you can even start things that normally don't transplant well like peas, beets, and cucumbers.
I've tried a bunch of things for starting seeds and rooting cuttings. The best, easiest, and most reliable I've found are Rapid Rooters or Root Riot plugs and cubes. They're peat-based, more similar to Aerogarden pods than Jiffy pellets though - very airy with just the right water holding capacity, piece of cake to transplant, natural, and everything I've grown in them loves them. Coco coir is also fantastic, pretty cheap, and somewhat reusable. Or coir + perlite to keep the mix light. You can learn a lot from cannabis growers, even if that isn't your thing, because they do not play around with anything that works poorly.
Last edited by SeanD1497 March 27, 2025 at 01:27 PM.
I've tried a bunch of things for starting seeds and rooting cuttings. The best, easiest, and most reliable I've found are Rapid Rooters or Root Riot plugs and cubes. They're peat-based, more similar to Aerogarden pods than Jiffy pellets though - very airy with just the right water holding capacity, piece of cake to transplant, natural, and everything I've grown in them loves them. Coco coir is also fantastic, pretty cheap, and somewhat reusable. Or coir + perlite to keep the mix light. You can learn a lot from cannabis growers, even if that isn't your thing, because they do not play around with anything that works poorly.
Agree with pretty much everything you say. I start with Rapid Rooters or Coir/perlite mix. For tomatoes, which you pretty much have to pot up, I use the cheap nursery bags[amazon.com] which allows for air-pruning. I don't think they are truly biodegradable, but there is about as much plastic in 300 of these bags as in one 5 gallon pot, so I don't feel so bad tossing them out.
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Have this, it is a dumb shape for a soil blocker and very inefficient. Before you spend a lot on a high quality traditional soil blocker just use the tray method
Pack a tray with firm, moistened soil mix, then score it into evenly sized blocks using a knife or spatula. Press lightly to separate them, make a small indentation for seeds, and mist with water to help them hold their shape. Once seedlings sprout, transplant the blocks directly into the garden—no pots, no waste!"
Agree with pretty much everything you say. I start with Rapid Rooters or Coir/perlite mix. For tomatoes, which you pretty much have to pot up, I use the cheap nursery bags[amazon.com] which allows for air-pruning. I don't think they are truly biodegradable, but there is about as much plastic in 300 of these bags as in one 5 gallon pot, so I don't feel so bad tossing them out.
I've used bags like that, too, and they do very well. Same deal as container gardening with fabric pots, which is super easy, as far as air pruning.
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You raise a valid concern, but unfortunately you tried to answer it with likely little basis in valid evidence. Styrofoam is a simple and very stable molecule. There is no strong indications that growing in Styrofoam cups at the seedling stage has significant effects on absorption of toxins into fruits and vegetables that come months after transplanting and have roots mainly in soil that never contacted Styrofoam. Then you'd have to look at whether watering washes away the theoretical leaching you are concerned about.
Like I said, I think your concern is valid, but where is the evidence of this measured contamination in growing seedlings in well drained potting soil in Styrofoam cups? Some studies show minor effects, and some even show beneficial effects, but in both cases, the researchers are purposely contaminating the soil with levels of polystyrene microplastics that would not occur from starting plants indoors for a few weeks. Even storing food in direct contact with polystyrene is considered safe so long as it isn't heated.
"Research suggests that polystyrene microplastics can sometimes stimulate plant growth, particularly root elongation, potentially by increasing carbon and nitrogen levels in the plants."
I put herbs in the 16oz. cups. I put big plant mass vegetable on the 20oz. cups.
Should be able to get at least 10 years of crops out of them, and protected from sun in the garage, I wouldn't be surprized if they last decades. Styrofoam is also an excellent insulator for the roots from rapid temperature swings. On year five now.
26 Comments
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Now after close to a decade of dedicated seedling production - I've settled on a 2-phase system.
1 - I start seedings in an Aerogarden seedling starting tray - where I let them sprout, and grow to about 4-6" tall (for tomatoes)
2 - I move them into round ~4" pots, with these carrying trays: https://www.greenhousem
The system works well, and if you invest in the pots and trays, they should last you for a decade or more.
Our community has rated this post as helpful. If you agree, why not thank rayoroa
1) air hits all sides of the block and dries out fast without proper moisture control
2) the blocks will fall apart without proper structural mix
If you decide to do this: google Elliot Coleman seed block mix. That mix is tried and true way of doing soil blocks.
Once you perfect this method, it's much better than cups. You can do a lot of seedling starts much quicker and the transplants are much healthier. What happens is the roots will hit the edge of the soil block where the soil meets the air and then the root stops and the plant will shoot out a new root. This is called air pruning.
What you end up with is a much healthier plant with a great root system. Using this method you can even start things that normally don't transplant well like peas, beets, and cucumbers.
Sign up for a Slickdeals account to remove this ad.
Pack a tray with firm, moistened soil mix, then score it into evenly sized blocks using a knife or spatula. Press lightly to separate them, make a small indentation for seeds, and mist with water to help them hold their shape. Once seedlings sprout, transplant the blocks directly into the garden—no pots, no waste!"
Leave a Comment