Newbie question #4080 pale seedlings

[dwood5513]

Long time lurker, this site is an incredible resource, I’ve learned a tremendous amount from just perusing pics, expert advice etc. i’ve felt really no need to add to a very large have no idea what I’m doing list of questions on here but,
I’ve been starting seeds lately, and generally having a little success, although not as good as I’d hope for. Anyway I wanted to figure out something I can’t seem to completely find the answer to here or anywhere else for that matter....

Pale seedlings.
I know low light is one cause, but usually accompanied with etiolating or elongating. I have some ferocactus seedlings that are extremely pale (almost white) but look nice and thick and plump (not as if they are getting insufficient light). I cannot take a picture of them since they are in a baggy, but I can describe the conditions.
Sterilized soil, vermiculite sowing medium, captan soaked soil, with a little sprayed in bottom of bag, 11w led grow lights, heating pad, small 3inch jar which I’m using as a pot. I have multiple setups so I moved them to an unheated, brighter t5 light bank since Ithought maybe they were too humid and warm. I’d really like to know some of the causes of pale seedlings, so I can correct it and not just haphzardly try random things. -Dave

[MagiCarpus]

Did they start green and turn white after you moved them under the T5s?

Most seedlings dislike strong light. The excess radiation and heat can destroy the chlorophylls in young seedlings resulting in white bodies.

Another cause could be rot, but in this case they tend to turn translucent rather than white.

[ElieEstephane]

I agree wirh magicarpus. Seedlings in high humidity will turn translucent white. Is your soil too wet? Did you water the soil in the jar which i assume has no drainage holes. You can open the baggie for a little time to take photos

[dwood5513]

Thanks for the help. I took a picture but I dont know what is a good hosting site, photobucket doesnt let you share pics anymore.

They did not start off green and have been pale since germination. I had them shaded since I feel like germination improves when shaded, but when they sprouted pale I took the shade cloth off, since I thought it wasn’t enough light.
So white seedlings can be caused by both too much light and not enough? I thought they turn red w too much light. So much to learn!
I will try covering and then “debagging”. Could be too moist.

[ElieEstephane]

Yes seedlings turn red in string light and then chlorophyll dies. Don't take off the bag before we see them. It could be something totally different than what is stated.
You can find photo resizing software on android, iOs and windows to easily resize your photos.

[dwood5513]

Didn't realize that you could upload to the forum.

fero2.jpg (28.71 KiB) Viewed 828 times

The top soil is horticultural sand I got at the nursery, which I sprinkle on the surface to dry it out.

[MagiCarpus]

They look fine.

freshly hatched cotyledons are pale green. The green will intensify with red flush in a week or so.

When you said white I thought you meant white like the quartz/perlite in your substrate.

[ElieEstephane]

Although not as green as they should be, they look fine to me. One option could be variegation. Differently colored areas wouldn't be clear at this age. Are they very slow growing? How old are they?
Here are some of mine. I thought they were sickly but turned out variegated. They have an infinitesimal amount of chlorophyll keeping them alive but i have no interest in keeping them alive if they can't live on their own

[dwood5513]

oh cool, i’ve grown ferocactus before but dont remember them being pale. They are about 5 days old. I was thinking about variegation, since apparently ferocactus californicus is an hybrid. Thanks for the help elieestaphane and magicarpus.

[ElieEstephane]

Oh 5 days! No then that's totally normal. I take back my comments