Droopy plants and yellow lower leaves

Hi, Im a first time grower and a first time poster her at RIU. I have been reading through this forum and learning for months. I have been growing 3 pants White widow, skunk 47 and northern lights for almost a month under 600w. Just under 3 weeks in I gave there first dose of nutes ( 1/2 dose bio-grow) which I guess probably was too much. They seemed to like it and grow for a few days after, then all of a sudden the leaves have started to droop and the lower leaves have gone bright yellow. I thought maybe I over did it and left them to dry out and gave them a clean watering a few days ago but they havent picked up yet. Should I just sit it out or should I actively be doing something? Im pretty sure I havent over watered, I have waited for the soil to dry out every time before watering.

Thanks in advance, I have had a search around but cant find my answer. Oh and the smaller plant was started a week and a bit behind the others hence the size different

They look dry and underfed to me.

They need more nitrogen

should i give them some water and a feed to see what happens?

Yes, that's what we're saying. Give them a full dose of nutes and water heavy.

I advise to immediately flush each plant with a half gal of distilled h20 or tap if necessary. If you over fed its time to clean out over nutes. Next I advised skipping a rotation of fertilizing this way you can check for results . The. After I week or better back to same sequence of feeding but definitely half dose of the half dose. Next check for water daily looks like you have high heat and your plant have suffered heat stress more than once.

Right, I already watered and fed the white widow and it sprang back to life! All the leaves are pointing up and its grown about half an inch.

Im going to try this for the other 2 and see what happens.

Justdewwit - what makes you think heat stress? They have been quite warm (85ish) so i have moved the light further away to let them chill a bit.