i would raise the lights a bit.. 3 inches is a bit extreme for a seedling. i start around 8-9 inches and work down to around 5-6 inches once they have a set of true leaves.. after that, they'll be able to make more use of the light and you can drop the lights to 3 inches when they have about 2-3 sets of true leaves. you can stunt growth if the lights are too close when they are just emerging and the light will just cause too much heat and tend to dry out the seedling because they don't yet have the root mass needed to be able to absorb the needed water.

i also limit the light to around 14 hours , i think 18 is too much when they are starting out and after they have more leaves you can give them more light.. the first 2-3 weeks you don't see a lot of top growth, most of the energy is being directed to forming the root structure first.

Ok, Ill make sure to raise the ligths right away and see if they like it better!

Thanks for the advice and feel free to give me more things to try =)

i would keep the fan off as well, or at least position it so it's not blowing at the seedling but rather at the fixture/bulbs to move the hot air away. fan will just suck the moisture from the seedling.. once they start getting bigger fan is good.

good luck!

Anything else to change or do?

There was an interesting comparison about seedling growth on another forum.> GrowDan rockwool "vs" Rapid Rooter grow plugs... Nothing can be done this season but you might rethink using rockwool cubes next year.

habjolokia z 6b/7, I know I should have patience but still I thought theyd grow faster than this, especially the tomatoes which are only 3-4inces high and were sown 1 month ago. I dont mind the time that much but I also want to know if I can do something else better =)

the_northeast_chileman, yeah I read that and will rethink for next year, although I will use a hydroponic drip system so rockwool slabs seems easy. I read alot of good things about rockwool before I tried this, guess theres pros and cons with everything.

What about my temperatures, are they ok?

tomatoes grow much faster then peppers. Also Chinense grow slower than Anuum varieties. I don't know which you have but this is something to be aware of (although Chinense once established grow pretty fast). Also I noticed a good amount of algae in your cubes. Algae can suck nutrients at a fast rate. If you were to cover your cubes with black plastic the algae would be starved of light and die off. You are only a few weeks into growing. After a month or so you should see much more growth. It can take 2 to 3 weeks for decent sized true leaves to grow. I generally wait for the first set of true leaves before I transplant. Transplanting can damage roots structure (some of them are only a cell wide before that). After you have 3 sets the plants will take off! (provided proper nutrition and pH).

> There was an interesting comparison about seedling growth on another forum.> GrowDan rockwool "vs" Rapid Rooter grow plugs... Nothing can be done this season but you might rethink using rockwool cubes next year.

there is nothing really wrong with rockwool, the problem is that it's easier to over water because they hold about 3 times more water than the other type of plugs.. so if they are too saturated the plant/seedling growth will be stunted due to suffocation.

when i use rockwool i always soak for a bit then i squeeze the cubes until it feels damp, but not too wet. kind of like a wrung out sponge.

I read somewhere that the algae wasnt a problem more then it didnt look good since its only on the outside of the cube?

And its really hard to get the right amount of water to the cubes. Soaking them before planting is one thing but when i have to water them theyre getting really soaked and ive had some problems with dampening off.. They get drie out pretty quickly too :/

Since I started this thread Ive gotten my EC and pH meters. I had pH 5.5 and EC 1.7 in the latest solution. I have now made two solutions, one for the plants thats made very little progress, pH 6.4 and EC 0.7. For the more developed plants im now going with pH 6.1 and EC 1.14.

ive also transplanted some of them, mostly the cucumbers and tomatoes. Those transplanted has been covered now to protect some from algae. Feel free to comment on what I should do differently and give me more suggestions how to do it better :)

Yes, some sallad and herbs there too, theyll be moved to an Ebb and Flow system any day now.

I started peppers at the same time you did and mine are a lot bigger. I think it's too cold, especially at night, and they are being over watered. Maybe try jacking up the temperatures to allow evaporation to occur faster, like the other poster said, rockwool tends to over saturate them, which they don't like. Plus they like it on the warmer side anyways. As they get older they should be able to deal with the over saturation, it's just hard on a young plant cause they can only suck up so much.

i've been using rockwool for on and off for about 6 years and never seen algae like that. i would try watering the cube when they dry out with some chamomile tea, about a tea bag for 1/2 gal. of water (steep it like you would any other tea) and let it cool then water the rockwool with it.. it should help kill off algae/mold without harming the plants.

i also think you're over feeding.. my meter reads in PPM, but looking up the EC to ppm chart, 1.7 is very high fertilizer concentration. for seedlings, you want to start them off around 200PPM, which is about 0.3-0.5 EC depending on the conversion chart you use.. naturally, pepper plants don't like a lot of fertilizer. i never go above around 600PPM. from my experience that is about the "sweet spot" for mature peppers. for tomatoes, from 800 up to 1000PPM for a mature plant. so to recap, start seedlings around 200PPM, once they're around 4 inches tall, increase to 300PPM, and slowly keep increasing about 100PPM each time as they continue to mature. once they're well over 12 inches tall then you can go to around 600PPM (for peppers anyway)..

if you're still using a fan, that is probably what is drying your cubes.. as i mentioned before, keep the fan from blowing directly on the seedlings (unless you're trying to dry out over saturated cubes).

i never liked bottom feeding when dealing with multiple plants because some will always over absorb the water (the ones closest to where you're pouring at), while others get very little. my advice is to start using a measuring device, like a syringe with a blunt tip. insert the blunt tip into the corner of each cube. that way each cube gets the same amount and you don't risk over saturating them.. i would say 6-8 mil should be enough for each cube. it's a bit more work having to water individually, but in the long run you'll run into less problems. i will say that top feeding only becomes a problem when you're adding too much water, this is one of those cases where less is more :)

IDK anything about those cubes, but they don't seem to be working for you. I would get them out of those things and into a traditional well draining potting mix.

I agree with peter. Move them into a well draining potting mix. You should have 4-6" plants by now.

I tried chamomile, maybe set the algae back some, dont know. I think the reason I have such horrible algae growth is because of overwatering, the surface was too wet..

Started watering with a syringe, that was a great suggestion! Much easier to control saturarion! Thanks!

Peter and esox07, the reason I stick with cubes is that I will transplant them to rock wool slabs in my greenhouse with a drip system circulating water later.

I have started som new cubes again just to test some of the many leasons I think Ive learned, see if they get better results. Ive also ordered some root riot cubes for testing. Maybe Ill do it differently next season.

Yah, I would certainly try something different. Your plants should be much bigger by now.

I planted these on March 14th.

March 14th? As in 2 weeks before that picture?....I assume you meant February 14th? If you planted those on March 14th I think you should call the Guiness Book. ;)

Those cubes seem to not drain and soak up water and look dense, not to mention contaminated with some kind of algae, and I can't imagine peppers being happy in them. Peppers like an airy well draining mix. But I have no experience with this hydroponic greenhouse stuff. I'm just saying... it doesn't seem like it is working. I'm not sure I really understand the allure of hydroponics.

60F at night is probably too cool. Pepper seedlings want it warmer.

Sorry, February 14th.

THis is what plain oil potting soil can do:

Those look great!

Ive done quite alot of reading during last year and found that rockwool seems to be popular amongst commercial greenhouses and since I have a dream to maybe open one some day I thought I should start testing them now.

Im quite convinced that Ive been over watering them and possibly over feeding. The cubes has been too saturated leading to heavy algae growth and stunted plants. I filled the tray they stand in with water, letting the cubes soak up from the bottom. But to make sure all cubes got some water I filled the trays with water, letting them stand in water for up towards a day before it evaporised/plants used it.

Yesturday I transplanted about 30 more plants to the bigger cubes, leaving 30 left in small cubes to be transplanted in a couple of days. I now have about 60 plants in the bigger cubes and they seem to be recovering and starting to grow now at last.

Perhaps you should try posting on the hydroponics forum.

I think OP realized it's being over watered, threads basically solved. I'd add that with cold nights of 60F and plants growing in a wet sponge basically put these plants to a crawl. Also 60F is very cold regardless of how wet it is because it's not growing in soil. That rockwool isn't exactly a good heat sync/temperature conductor. At 60F in the night, those rockwool cubes would be very cold, on the flip side, with soil, this wouldn't happen because soil can store energy and heat better, thus it would take a lot longer for soil temps to reach 60F compared to rockwool. I think these temps and saturation levels would have put most plants to a crawl.

Yes I just meant for hydroponics advice in general.

Yah, some people have great success with that hydroponics stuff. And there are not a lot of people in this forum that are real experienced with it. Peppers, yes, hydro, not so much. I give OP some credit for sticking with it. If it was me, I would have given up by now. But, for where to go from here, it is probably best he try his luck over in the hydro forum.

peppers are one of the most difficult plants to grow in hydroponic due to the fact that peppers don't generally like much water (wet feet) or fertilizer (nitrogen)..once you get the hang of it, it's rewarding. nothing like seeing a plant grow 2-3 times faster than if it were in soil. i grow both in soil and hydro depending on my mood ;)

Aye, I have alot more to learn and test before I see those growths, but I will keep trying!

Time for an update, still sering really slow growth.. Most of the plants look good though so I guess thats something at least..

This photo is 5 days old:

But some plants really curl up their leaves , nothing different with lights, fans, temp then their neighbour who looks really healthy. Any idea why? Is it a problem?

is there a variation in the heat they are receiving?

No, they all get the same heat, lights and air flow.

The big rock wool cubes got drowned before transplanting the small ones so they have kept water for very long time now, hasnt even watered them once. And Ive checked that the Naranga on the picture has plenty of moisture to live on. Maybe too wet? Odd that some doesnt show any curling at all, even of the same variety.