Freaking out!!!!! All my seedlings were green and thriving and suddenly they're all turning brown and drying up. Is this something that happens to seedlings indoors in August? What's going on????

Not usually, Christy. A picture would help if you could post one.

Did you maybe fertilize them too soon? Baby plants can't use much fertilizer, it will burn the leaves and turn them brown.

Or did you put them out in the direct sunlight too quickly? Again, baby plants need to be treated tenderly and acclimated gradually to the brightness of natural light, unless they germinate outdoors on their own.

Not only would pictures be helpful, but knowing the variety of seedlings you have would be helpful too.

Indoors in August...do you by any chance have the air conditioner running inside your house?
I agree, we need to know what kind of plants and photos would be a big help.

If you look, you can see the ones dying also in the background. They are all different seeds from plants like Big red wagon, Face the Fire, fringy etc. Am I suppose to already have them outside? Do seedlings foliage die like the ones outside are in August?

So they're daylily seedlings. What are they planted in, it looks like a mix of vermiculite and perlite? What is their light source, and what have you been fertilizing them with, if anything. Also how long since they germinated? I would say they don't usually die back in August indoors unless they have a problem, and they certainly don't look too good, unfortunately. Usually outdoor ones don't completely die back in August either unless it's been very hot and dry and they go into "summer dormancy". They can get kind of ratty looking after flowering though.

Christy, it looks like you planted them in drink cups - did you punch enough holes in the bottom of the cups for good drainage? It's possible the drainage holes are plugged up now, if they were too small or too few.

Any that are still green, I think you should maybe scoop them out of their cups and put them into some fresh, sterile potting soil. Be very careful not to destroy any live foliage, and to preserve as many roots as possible.

If the medium is too soggy lower down, when you scoop them out, set them on a paper towel or something absorbent to dry out the medium right away.

Pardon me for being dense but if you are in zone 7a may I inquire why are you keeping these plants inside the house in plastic drink cups. Why not plant them in regular pots and let them go outside for a bit of indirect sunshine? There must be at least a porch step or patio or someplace for these plants outside.

Those seedlings could have been outdoors all summer, growing in the shade.

It may be that the seeds were only started indoors a few weeks ago. In that case it wouldn't be unreasonable for them to be still indoors, which is why I asked how long since seed germination. Christy did post about seed/ling problems in another thread earlier in spring, though, but the medium looks different so I'm wondering if this is a new batch. If they are recently sown then perhaps next time they're started during the growing season it would indeed be better to sow them outdoors (in the ground) to start with.

I think I figured it out!!! Lifted up a cup and sunlight hit tiny hairlike web all in between leaves at base of plant. Started checking and they are all like that. Spider mites I read. How do I treat seedlings for that?

Spider mites, ouch.

If those were the only problem, and they've already sucked the seedling leaves brown and dry, it might be too late.

Until someone more experienced comes by, consider some of these remedies:

1.
Spray with a hard, stinging mist of water, like you would get from an irrigation mini-jet sprayer running at 40+ PSI. Knock off as many as possible! Be sure to spray up form underneath, down from above, and in-and-around everywhere those mites laid eggs. repeat often!

2.
Also swab with soapy water, trying to wash them off AND kill them with normal soap.
Repeat fairly often. Can you dunk the leaves completely under soapy water?

3.
Spray heavily with insecticidal soap. Probably more than once, every ... ummm ... weekly? You have to kill them as they hatch from eggs.

4.
Potent chemical insecticides. I guess malathion is now available only as a war gas, so that's out.

Pyrethrins? They are thought to be more "green" since they were originally derived from Chrysanthemums (now produced industrially.) And they are biodegradable and less toxic to humans than many insecticides.

5.
Start new seeds and think about what environmental conditions might discourage them next time. I THINK they like dry leaves, and frequent hard-mist-sprayings knock them down (or maybe just discourage them with humidity - I don;t know.)

Rick's got the right ideas there, Christy. Soap is the enemy to spider mites but for your tiny plants, it might work even better to just get soapy water on your fingers and run them down the leaves. Then rinse off with a gentle spray of water.

Yes, you do need to repeat the soapy water treatment maybe every 5 days for a couple of weeks to get all the new generations hatching out of eggs left behind.

Then, once the survivors (plants that is) start growing again, mist them gently with a hose sprayer at least once a week to keep the evil little mites away.