seeds Seedlings stopped growing..

Pfeffer

Pfeffer

Hi all,
 
Just a quick question. I'm not an unexperienced grower, but somehow my seedlings stopped growing. I usually grow them up without heating, but this year I started them in a new heated 50w propagator with thermostate. This is covered by a 2x55w TNEON light (6500k) for 18/6 in a steady 28 Celsius/82 F (24h).
 
My first few batches since October went great, but my latest batch simply germinated and... stopped.
 
I can't say I'm overwatering or stressing them in any way. The hood of the propagator is usually closed, with the vents open or with a screw between to bin and top cover to enable a bit more airing. The only thing that was changed was the sowing mix (went from Intratuin brand to the more expensive Plagron sowing mix). Both are not fertilized but currently some of the slower growing seedlings are still planted in the old sowing mix. I'm afraid I didn't keep track on which ones got what sow mix, but all seem to have stopped.. so I also doubt it's related to that.
 
Some pics;
 

Capsicum Rhomboideum 31-Dec-2014
 

Capsicum Rhomboideum 12-Jan-2015
 
I figure I have some slower starting varieties, like the rare wilds (buforum, eximium, lanceolatum, microcarpum, galapagoense, chacoense, praetermissum, cardenasii, tovarii etc) but even the annuums seem to be growing extremely slowly.
 
I'm not able to make correctly coloured pics, but the leaves look a bit whitish yellowish with purple/black pigment speckling, instead of the yellowing as with overwatering. I also have some early cotyledon drop (with 1st or 2nd pair of true leaves).
 
One of the seedlings look to have some kind of white burning, which doesn't look like a nute or light burn.

(The leaves or not as yellow as they look, that's the lighting)
 
The older plants started in a earlier batch, grown exactly the same look a lot better and receiving their first nutes (the seedlings don't get nutes offcourse).


 
Anyone has an idea what's going on? Might it be shock from the lighting? (though I can't say it's closer than with the first batches).
 
They fine,may be in a little stall stage because they arent getting the right amount of light? Ive had seedlings ive kept in propagation trays for 6 months that got stunted at 5 inches. Threw them on the greound with some fert and they grew like wild flowers.
 
The dual 55w (3800 lumen per bulb, 6500k worked great for the first seedlings.. those are the plants currently on the refrigerator (those were sown 08-Oct-2014) and the ones in the cabinet (also lighted with a dual 55w tneon) so I don't thing it's the light. If it was the light I would expect them to be stretchy and weak. Now they are just.. well.. weak, not stretchy : -)
 
I see you have one of those electronic fly swatter things next to your plants. Do you have fungus gnats? The larvae could be eating the tender young roots of the seedlings.
 
It could also be the water you are using. The ph of my tap water changes with the seasons. In the spring, summer, and fall it's pretty close to neutral, but in the winter it's very alkaline and plants hate it.
 
You might want to check the pH of the water run-off from you soil and see if that is in the range for the plants to uptake nutrients.  I've seen it many times before the pH of your mix gets out of wack and the plants stop growing.  The older plants which received nutes probably had a pH buffer that helped bring the pH in to range and why they are growing.  Even if you are just watering straight water it is best to pH balance, tip of the day.
 
speaking of water you guys would not believe the iron in our water. Our iron filters to our house woud blow your mind,lol. 
 
a veteran grower on here has me use nursery purified water . thats what he's been using for years . might check soil temp , maybe to warm breeding fungus ? 
 
All great suggestions above. I'll add my 2 cents, did you sterilize your containers before putting new starter mix? If not, bacteria in the soil might be causing stunting. As mentioned above though, good chance of recovery after potting up or into the ground. If you did sterilize, ph would be my first thought.
Good luck
 
To be honest I don't reuse containers, I get cheap discardable ones instead. I unfortunately don't own a decent ec/ph meter so I'll try it with my litmus, but I don't think it will give a proper reading.

Another tip I got from a different forum is to lower the night temp. As this is the easiest fix i'll try that to start with. I think I might ' ve done that with the first batch as well, to save energy. Didn't even think about that.
 
plants look good. Unless you see some signs of something going wrong I wouldn't worry.
 
Maybe you should fertilize LIGHTLY with a 10-10-10 and see how it goes.
 
Yes I have some fruitflies, but it's nothing near an infestation. I just tested my tap water and found out the PH is over 7. Colourwise it's around 7.5-8 which is very alkaline imho. These are just pH litmus paper strips, so nothing fancy and accurate.. but the idea is there.
 
To combat this issue I ordered Plagron pH-  and a Eutech pH2 pH-tester. I hope it also helps with general growing. Should I combat the high soil pH by watering with low pH (i.e. 5.5-6 pH) or should I simply start with normal pH (6-6.7)? And most of all, if this is the cause.. will it sort itself out with watering with correct pH or should I consider resowing (luckily I still have sufficient time to do so).
 
miguelovic said:
What are the details/specifics of the different soils used? Curiousity more than anything.
Click to expand...
Both are standard seeding/cutting soils, both pH 6.0 - 6.5 according to the label. Ingredients are pretty much the same. Soil and a little peat by the looks of it.
 
This is the new one with the problems, it mentions guano but a very low EC value. So I don't think that is the cause. I already checked to make sure and found a little bit different texture between the two soils (old and new). So both the old and the new mix have the same issue.. where earlier batches went great.
http://www.plagron.com/nl-nl/product/1/46/44/seeding--cutting-soil.aspx
 
I received my pH tester and pH- (phosporic acid) today and did some checks. My tap water is 7.9 - 8.1 pH, depending if I use the hot tap or the cold tap. The test fluids of 4.001, 7.001 and 10.001 pH are spot on. The run off water with tap water (I saved some) also comes in around 7.6 but I find it difficult to get a decent reading on that (only had like one table spoon of the liquid, can't really dip it correctly).
 
To counter the high pH I brewed up a 5.8 pH batch, with just a pinch of magnesiumsulfate (epsom?) on 1 liter of tap water. I used this to water the seedlings in the hope that it will counter the hard soil pH.
 
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