Hardening off advice?

Hi all, I'm growing peppers from seed for the first time this year. I've been growing the seedlings in transparent solo cups (double-cup method), and I didn't have a fan on them. They're not looking that leggy, but I did transplant a reaper to a large pot and it's been outside for a couple weeks and it's not looking too good. Previous to transplanting it, I set it outside with the rest of my peppers, and it was probably the heartiest plant of the bunch, so that's why I selected it to get transplanted as a guinea pig. I guess my question is how do I know when they're ready to move to bigger pots and ready to move outside? I've been watching the roots, they're visible on the exterior of the cups, but not root-bound. Some look more ready than others, but how do I know when they're ultimately ready?

I've got fabric pots, and all the topsoil/manure/perlite/vermiculite/peat moss to get going, and I'm eager. I just don't want to jump the gun and see them all die!

How do I know they're hardened off, and if they're not hardened off, how can I speed up the process? I take them outside on sunny days, but the weather has been shit around here lately, so maybe once a week for a few hours or more. I think I was a little overzealous in the beginning; some of them have signs of sunburn.

Also, one of my Tepin plants still only has two leaves. I'm waiting for this runt to grow bigger, but it is seriously taking forever, and I doubt it's going to catch up to the rest of the bunch. Do you guys think it'll get better, or is it a lost cause?

I'll post pics if necessary. Just hammering out the words, now.

I normally just wait to transplant until they are hardened off and ready to go outside. After a couple of seasons you will learn when to start your seeds so that they won't be root bound or too big for their cups/pots. But if they are root bound, it's not the end of the world, just make sure you break them up real well when you transplant. As for hardening off, cloudy days are your friend so don't avoid them. They will still get more light than they do inside. Gradually give them more sin and watch them close. When they can withstand several hours of midday sun, then they are ready.

2-7 days place in full shade under a tree or something. indirect light is still pretty bright compare to indoors. (like shade is not completely black you can still see in it eh?)

2-7 days place in half day sun. evening and morning sun are less intense easier for plants to acclimate to. put near the edges of your shade from above. or put on the east or west of a structure. (will be lit/shaded half the day after sun passes mid point)

good to go

going from 2-10k lux from an indoor setup to full 100k + sunlight will kill plants. even a couple hours is enough to kill leaves.

also cloudy days are great for hardening off

lux table for reference approximates:
full sunlight 100k
sunny day shade 15k
cloudy day 2k
sun rise/set .4k

indoor room light 200-1000 lux
indoor grow light 10k lux

Here are pics of the peps and a close-up of one of my more developed peppers roots (Tepin in first pic its the one on the far left of the pan on the left, closest to the porch side):

Edit (sorry root pic is sideways; mobile upload, hopefully it still gets the point across)

Edit 2: pic 3 is of my runty Tepin. Pic 4 is of the Reaper that I transplanted too early.

Gradual exposure is the key.
 
I have always started with about 4 hours of shade for two days, then add about a half hour of direct sunlight per day until they are getting six hours of full sunlight per day, keeping a close watch for sunscald.
 
However, reading juanitos very informative post, I should not need that much time, as according to my calculations, my 12 lamp T5HO fixture that the plants have been under since germination is putting out ~50K lumens in an 8 ft2  area, or ~65K lux.
 

 
https://www.rapidtables.com/calc/light/lumen-to-lux-calculator.html

alkhall said:

Gradual exposure is the key.
 
I have always started with about 4 hours of shade for two days, then add about a half hour of direct sunlight per day until they are getting six hours of full sunlight per day, keeping a close watch for sunscald.
 
However, reading juanitos very informative post, I should not need that much time, as according to my calculations, my 12 lamp T5HO fixture that the plants have been under since germination is putting out ~50K lumens in an 8 ft2  area, or ~65K lux.
 

Capture.jpeg
 
https://www.rapidtables.com/calc/light/lumen-to-lux-calculator.html

Click to expand...

 
it's not just lux intensity.
 
the sun has more UV radiation that the plants have to get used to.
 
https://en.wikipedia.org/wiki/Sunlight#Spectral_composition_of_sunlight_at_Earth's_surface

juanitos said:

 
it's not just lux intensity.
 
the sun has more UV radiation that the plants have to get used to.
 
 
<a data-ipb="nomediaparse" data-cke-saved-href="https://en.wikipedia.org/wiki/Sunlight#Spectral_composition_of_sunlight_at_Earth" href="https://en.wikipedia.org/wiki/Sunlight#Spectral_composition_of_sunlight_at_Earth" s_surface"="">

 

Click to expand...

 
 
True, that is why four of the twelve lamps are Eye Hortilux FS+UV.

2nd year doing this after keeping them in a south facing window sill for a week or more....Seems to work great. I just leave them under it all day until they are ready for pots.

ShowMeDaSauce said:

2nd year doing this after keeping them in a south facing window sill for a week or more....Seems to work great. I just leave them under it all day until they are ready for pots.

Click to expand...

Here is where Ive been keeping my peppers inside. Its a south-facing window, but there is a two-story apartmemt building probably 15 feet away, so they mostly get morning and evening sun unless I take them outside.

I just transplanted one of my Orange Scorpions to a 5gal fabric pot, and I intend to leave it on the porch steps to see how it fares. If it survives, the rest can get transplanted (Of my seedlings, mostly Reapers and Scorpions thrived, while the rest werent as fortunate. I blame the crooked foundation of this apartment for directing the water to one specific side of the growing tray I was using.)

This year I am testing non hardened versus hardened. I like doing tests like this since I have millions of veggie seeds. I have been able to go from indoor grow tent to outdoor with about 30% of my plants. Tomatoes, Peppers, Pumpkins and Broccoli were able to deal with it ( overall ) but things like cantelope, watermelon and cucumber however didn't deal with it at all and are all dead BUT I see signs of life in a couple.
 
This was a small test though. Not using any hot pepper seeds that I recently bought but rather old stock seeds that I have had for years. I am going to take cuttings from the ones that made it without hardening and turn them into mother plants to work with and see if I can expand the non hardening needs.
 
I wouldn't do this with anything I spent time/money on though and not suggest it to others unless you have a ton of seeds to play with.
 
In my climate ( we have negative degree day/night and random rain/hail ) I would suggest hardening everything but places like Cali and others I would think many could make it a-ok but odds are still have losses. Still something I think is a benefit to test and work with over the years. The term cold hardy comes to mind but something tells me that you could expand on just how hardy they are based on your breeding/selection.

My poor babies have been outside in the pouring rain for days now. I did take them out of those white tubs. Temps dropped down into the upper 40s but they all look ok. I did bring in my bhuts and bonnets though after the first rainy day/night just because i cant risk losing any.
 
Looks like they can start getting planted tomorrow

It will still get down to 39F (4C) at night for the next 3-4 weeks, so the only things I can harden off at this moment are my pubes. They have been outside for some time already but it has been overcast and rainy. One of them still got a sunburned leaf today, shit happens. The sun is coming in at a really severe angle now during the spring and as a result it's almost impossible to find a shady spot. The wind is also gusting quite powerfully, so I had to clip them onto their support sticks. Kind of hard to move them around too much now as they are already in very large pots.
 
When it comes time to harden off the rest of the stuff, I'll probably just need to spend an entire weekend outside with them moving them from place to place and giving them water. It is nice to use cloudy days when you have them, but seems those are over for us now for a while. Quite many times, I have hardened plants off in two days during full-blast sun just by moving them in and out of the sun every half hour or so and giving them water to keep the roots cool. Yes, I think it is silly but if you don't get a few cloudy days at the right time then I guess you need to do what you need to do.