health Why are my seedlings falling over?

[FinInGermany]

Hi folks, wondering if someone might have an idea why a load of my seedlings seem to not be able to hold their heads up?
For info, all planted on January 31st, sprouted between February 4th and 8th (pretty quick, I reckon), humidity dome removed on 11th, and since then they have had a light about two inches above them for 12 hours daily, and a weak breeze from a fan for about 2 - 3 hours daily. Still sitting on the heating mat, so soil is at 28°C.
All looked fine until a couple of days ago, when they started dropping .

 

[FinInGermany]

Boy, those seedlings are stretching for some light! They’re more than likely ‘top heavy’ and bending over fromfrom the excessive stem length. The fan breeze is probably contributing to the issue as well. The stems aren’t able to withstand the weight nor the air pressure from the fan. Humidity domes are the scourge of many growers not familiar with their intended usage. Anything living in a ‘bubble’ will be affected by the removal of it. The longer it’s grown like that will affect its performance (stunting). Dampening-off disease thrives in ‘domes’, too. How are they looking now?

A few have started righting themselves, but most of the dodgy ones are still lying there looking pretty sad and skinny. I'm on holiday now for a week and we're off to a hotel for a few days, so whatever hasn't gotten its act together by Wednesday afternoon will be going to compost. I still have plenty of seeds and more than enough time to replace the lost ones, so no real damage done, and something new learned.
What I WILL do in future is use single seed cells instead of trays, which will allow me to remove them individually from under the dome and get them under the light as soon as they germinate.

 

[FinInGermany]

If you want to stir up drama in an online gardening forum, simply ask, “Can you plant peppers deeply like tomatoes?” Then make some popcorn, sit back and watch the sparks fly.

I made the mistake of believing what somebody told me in an online forum for pepper growers . Well I'm sure happy to find that some folks on here have tried it themselves and proven that it can be done, cos I'll be giving it a go when I transplant some of the leggy ones in a couple of weeks .

Just had time to read the article there, bud. Well worth checking out, thanks .

 

[FinInGermany]

Just reading a book The Wife bought me, written by a couple of German chili freaks, which states that once the seedlings are a few weeks old, they should be subjected to cooler temperatures in the morning (around 14 - 20°C) which should then be increased to around 22 - 26°C in the afternoon, mimicking what actually happens in nature. Apparently this discourages vertical growth and make the plants grow more compactly.
Sounds credible, although I had never come across this in any English language literature on the subject. Probably as close to a stupid question as it gets, but have any of you guys heard this one before?

 

[Bou]

I don't think I have but it is not something I'm trying to control indoor anyway. When the light goes out, the temperature begins to drop. The nighttime temperature will always get a little lower than the daytime temperature.

 

[alkhall]

Just reading a book The Wife bought me, written by a couple of German chili freaks, which states that once the seedlings are a few weeks old, they should be subjected to cooler temperatures in the morning (around 14 - 20°C) which should then be increased to around 22 - 26°C in the afternoon, mimicking what actually happens in nature. Apparently this discourages vertical growth and make the plants grow more compactly.
Sounds credible, although I had never come across this in any English language literature on the subject. Probably as close to a stupid question as it gets, but have any of you guys heard this one before?

Never heard that before, but, as Bou says, the lights generate heat, and is naturally cooler at night anyway, so it does make sense.

14°C (~57°F) is a bit cool for room temperature in the house for me, especially now, in the winter. I generally keep my thermostat at 67°F (~19°C).

Just checked my temperature under my lights; ~90°F.

 

[FinInGermany]

I don't think I have but it is not something I'm trying to control indoor anyway. When the light goes out, the temperature begins to drop. The nighttime temperature will always get a little lower than the daytime temperature.

Yup, that figures, Bou. Too late to do anything scientific this year unless I want to have about 100 plants too many instead of just 50 or so, but I think next year I might do a control where I plant 2 identical trays, and turn the heating mat under one of them off overnight once they've sprouted, leaving the other one turned on.

 

[FinInGermany]

Never heard that before, but, as Bou says, the lights generate heat, and is naturally cooler at night anyway, so it does make sense.

14°C (~57°F) is a bit cool for room temperature in the house for me, especially now, in the winter. I generally keep my thermostat at 67°F (~19°C).

Just checked my temperature under my lights; ~90°F.

14°C is a bit on the cold side for my old bones in the living room nowadays too, but the room where I have my seedlings isn't heated. The soil temperature in the greenhouse where my seedlings are is around 24°C. The trays with seeds still waiting to germinate are higher up and covered, so although they are above the lights and don't get any direct heat from them, the temp is about 30°C.

 

[Bou]

Yup, that figures, Bou. Too late to do anything scientific this year unless I want to have about 100 plants too many instead of just 50 or so, but I think next year I might do a control where I plant 2 identical trays, and turn the heating mat under one of them off overnight once they've sprouted, leaving the other one turned on.

Just a thought here, but if you intend to do this it would be a good thing to monitor the ground temperature as the air will cool much faster than the soil (will act as thermal mass). Also, with the use of a heating mat for both trays I am not sure that the difference will be significant but I might be wrong....

 

[Marturo]

Just reading a book The Wife bought me, written by a couple of German chili freaks, which states that once the seedlings are a few weeks old, they should be subjected to cooler temperatures in the morning (around 14 - 20°C) which should then be increased to around 22 - 26°C in the afternoon, mimicking what actually happens in nature. Apparently this discourages vertical growth and make the plants grow more compactly.
Sounds credible, although I had never come across this in any English language literature on the subject. Probably as close to a stupid question as it gets, but have any of you guys heard this one before?

I have temps from 67 F in the AM to 76 F in the PM.
4 LEDs & 2 48" x 21.75 heating mats & a small oil filled heater.
The room is 12' long by 6' wide with styrofoam on walls covered with space blankets.

With the 2 8' fluorescents & 32' of heating cables I had to install an ex fan with cool air vents
just to keep the room out of the high 80s. Too hot is not better than cooler. The thermostat heating pads
work better when the room is cooler. All vents but one small 3" pipe are not used any longer.

 

[FinInGermany]

Just a thought here, but if you intend to do this it would be a good thing to monitor the ground temperature as the air will cool much faster than the soil (will act as thermal mass). Also, with the use of a heating mat for both trays I am not sure that the difference will be significant but I might be wrong....

That's a definite. Always measure the soil temperature, as that's what the roots are sitting in . Won't know for sure until next year, but I think turning a mat off overnight for eight hours or so could make an appreciable difference to the soil temperature in my small setup, when the other one is running almost constantly. Here's a pic of what I'm using. The ungerminated seeds are up top, where it's about 4 deg C warmer and there's not much light.

 

[FinInGermany]

With regard to burying the stems; I actually do that to some extent, both when potting and when planting out. However, using well-draining soil is key, and I let the topmost layer of soil (1 inch or so) dry out between watering, so there really is not a lot of moisture in the soil that is in contact with the stem. Not apply water directly on the stem probably helps as well.

Found a couple of my Thunder Mountain Longhorns stretched out having a rest this morning but looking otherwise undamaged, so I decided to try this myself instead of just chucking the seedlings out. Transplanted them into pretty deep plastic beakers in moist, lightly fertilised soil, then added dry soil on top until about half of the stem length was buried. Should know in a week or two whether it has had the desired effect .

 

[FinInGermany]

Well those two are heading for the compost after all. Doesn't mean it doesn't work, of course. Just that it didn't work with these two this time round .

 

[JAB Farms]

Found a couple of my Thunder Mountain Longhorns stretched out having a rest this morning but looking otherwise undamaged, so I decided to try this myself instead of just chucking the seedlings out. Transplanted them into pretty deep plastic beakers in moist, lightly fertilised soil, then added dry soil on top until about half of the stem length was buried. Should know in a week or two whether it has had the desired effect .

funny you should mention the Thunder Mountain Longhorns as this is the first time I have attempted to grow them and have noticed the seedlings (unlike the other 1600 Hot Peppers I started) - are a little leggy. When it comes to transplanting, I do bury a little of the stem in the peat/vermiculite/perlite/compost mix but I usually do not bury them too deep when putting out in garden or in buckets. I just transplanted (deeper) those yesterday from the plastic trays into 3.5 inch peat pots and a few into 3.5 plastic pots... and Yes, I said 1600+ started. Lol.

I also don't use a heat mat at all. Start with lids on trays and put plastic over the shelving units to hold in some extra heat.

 

[AtomicArmadillo]

Hopefully you saved them. After you harden them off you can always prune them back close to the base which will fill them out more.