Has anyone used these "sponges"? I have a problem...

I bought these spongelike plugs on ebay, they are approx 1.5 inches tall and an inch square which is tapered at the tip. Very spongy but supposedly made of "composted organic materials" such as peat and bark, bound with some kind of polymer. Seeds germinate very readily in them and the roots travel through them very very easily & quickly. So it sounds all good, right? .... .... ...
Well, a few plants seem to sprout and remain yellow - such as tomatoes, parsley and par-cel (herb), brugmansia (but not datura). I planted the yellows in soil... now the new tomato leaves are green but the brugs are still yellow. I misted with kelp water and watered in a weak fertilizer but no change. Could it be the pH? or something else?

Any help is appreciated - I really like the way these sponges work but if the plant won't be healthy, it's not gonna fly.
Eileen

Maybe you need to consider a diluted liquid fertilizer? Does it say anywhere on your product what amount of nutrients it contains?

Here's the auction - I don't think it has built in fertilizer, so as soon as my sprouts had a couple true leaves I used diluted fertilizer solution to water ... that's why I wondered if it is the pH ... do you think some nitrazine (pH) paper would tell me anything?

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2386268187&category=43555

Are your starts/sprouts getting enough light? But it sure could be the PH since the auction doesn't mention what type of bark was used in their manufacture. Soak on eof the plugs in some distilled water for a bit and than test with your litmus or nitrazine paper.
Lets us know what you find out....this is very interesting to me as I ma working on developing a starter plug myself.

RikerBear

Riker, Worms Way has a starter plug they sell in bags of like 25 or 50. They told me people go crazy for them and they use them as well. It might be some interesting reading for you or a comparison. They sure looked nice and rich but I did't buy any. I think we are all looking for the best, easiest and clean way to go. ;)

Thanks Badseed, I'll look into those :-)

Park Seed has some that they call bio-sponges. I've got some seed planted in them. A few are up, and so far doing well. I'll report if any problems arise.

yellow leaves make me think they're too wet and the roots might be rotting.

Hmmm, maybe they were wet at times, but not consistently. The sponges are extremely porous and the roots are all over the place (and look healthy). And I have the stuff under growlights too. I think it might be a fertilizer problem. As soon as I gave a full strength dilution a couple times, they really greened up. The herbs recovered first, then tomatoes, now sloooowly the brugs are catching up. Although pH might be a contributing factor...now where's that nitrazine paper? I'll post again once I've tested pH. I'd love to hear about the Park Seed bio-sponges, maybe they would be a better choice.
Thanks for all the help!
Eileen

By the way, my name's Eileen too. Not too often that I see it spelled our way. Have a great day!

I haven't used this particular 'sponge'. I do use the Park-Starts cylinders with best results. Especially starting Petunias. Very high germination rate. Each year I use this system more and more.

The cylinders are composed of pasteurized, disease-free peat moss held together with a flexible binder that holds several times its weight in water.

Water from the bottom with a weak solution of fertilizer. When transplanting, bury the cylinder below the soil surface to prevent excessive wicking.