Can seedlings die from direct sun?

[TonMz]

Left my seedlings out in the sun today, my foxglove trays totally died and my pea shoots all drooped dead also. Calendula looks all messed up. My pepper seedlings survived.. My usually indoor lentil sprouts drooped but my outdoor down lentils thriving as ever! Not sure if sowing outside is the best answer for overall hardier plants because from day 1 they adapt to wind, sun, a bit of cold during the night.. My only set experiment is sprouted store bought lentils which I sowed half the batch in a balcony trough and the other half in a plastic shallow container (cherry tomato container from Morrison's)... The outdoor are thriving despite changing weather conditions, and changes in watering habits.. A little over watered or under watered and they don't flinch! My indoor batch.. Outside for a few hours, droops.. Otherwise hardy with moisture changes. Pepper seeds were planted from a Morrison's pepper... They've survived changes from being moved on and off the balcong, to all day sun outside or growing inside by a shady window...moisture changes, a day or so of drought.. I'm sad I lost my foxglove flower seedlings, beetroot seedlings and calendula flower seedlings also. I failed with beetroot seedlings and carrot seedlings when planted in a wide tray for microgreens, and also in seed trays.. Before.. Now in seed trsy cells individually , carrots still didn't germinate and beets did but died today in the heat..EVEN though all my seedling soils were extremely well moist with twice dailg spritzing of leaves and soil...the heat today still destroyed them.. Really shows me that when down indoors.. They need gradual hardening off... Very difficult to see physical evidence of hardening off being a real need and affective, it's almost emotional because... Hard to see why.. But yes, they will totally drastically drop when introduced to an outdoor temperature or sun without window filter... For lengthy hours without breaks if not been adapted gently. Trauma for them. Glad to learn this the hard way early because I'm mainly taking a few risks to find out what is necessary and what is just myths...

Well I learned. I'll plant more foxglove seeds tomorrow... I'll keep them inside absolutely until hardened off..

My peashoots in the POT are totally fine and maybe that's cause their SOIL is deeper than the shallow plastic batch, so they retained more moisture..

Funnily enough the seedlings in the wide trays which all fell flat.. Look pale anyway which could be also why they dropped so weak, essentially, being sown indoors...they didn't get enough light by the window as we're not south facing.. Then as soon as it was very sunny today , I was eager to give them maximum sun but it doesn't work that way obviously, the stability of conditions are most key for all living beings even when in poor conditions.. Putting any living being who's conscious into a drastically BETTER condition or giving them too much or something they were deprived off is still not a balanced care.. So yeah, third attempt at my microgreens.. These wide seed trays were kale, lettuce etc and they all dropped. But are quite white stemmed so I need to really germinate by a window so as soon as they pop up they are well lit... And maybe grow light exposure for first week to build strong roots and stems before trying to put them on the balcony or even by a dim window so they have a good start..

These are pictures of my pea shoots which were standing tall this morning. My foxgloves were also healthy and were totally crushed and almost even decomposed in their seedtrays.. I thought they would thrive like when i put seedlings under growlights but apparently full sun is way more than a growlight for them.