Yellow Cotyledons on seedlings?

[ultima]

When my seedlings break the ground the cotyledons are yellow?
Some seem to recover and turn green but most of them stay partly or completely yellow resulting in tiny little leafs and weak plants.
I keep them in the dome until they break ground and then move them under my 250w CFL. I tried extending their stay in the dome ,I tried shortening their stay as well. Still they come up yellow?
Any ideas ? Tried googling it but no luck.

Thanks.

 

[LiLWaynE]

what do you start your seeds in?

 

[uefear]

First of all, why are you using a dome? Domes are for clones, not seedlings. Lose the dome my friend.

Second, if your cotyledons are coming up yellow it means the medium is either too hot (to much food) or your pH is more than likely off.

 

[lysol]

When they break the ground they could not have enough clorophyl, they start out palish white / brown and eventually gain color with minimal exposure to light. Most of the time they green up before they even break soil but if they are turning green a day after they sprout it just means it finally got some light. You aren't fertilizing your seedlings are you?

 

[ultima]

Lil Wayne -I start them in Jiffys, btw having a hard time knowing how much to water those little things. The reason I kept them under the dome is that they were having a hard time losing their shells- seemed to dry up quick and make it impossible unless i kept them in humid conditions. Most of them come up with the shell still hanging on I wonder if that means I plant them too shallow?

A couple of seedlings even dropped their cotyledons- only tiny leafs remaining and a bigtime stunted seedling.

I have planted about 20 beans in the last week , first ones came up fine and then it started going bad with the yellow cotyledon syndrome. Didn't change anything.

Im not fertilizing them , only water.
My water PH from tap is very alkaline - about 8 Ph.
Tap Ec is 0.1
I bring down the Ph to about 5.5.to 6 and use that to water them.
Temps 25-28 celsius. Rh under the CFL 35%.

 

[uefear]

You should water with higher pH than 5.5-6.0. Try 6.5-7.0.

Also the dome just cuts off fresh air exchange and irritates your seedlings. The reason people use domes on clones is to promote root growth (and they usually cut the leaves as well) as well as prevent to much transpiration.

 

[LiLWaynE]

i wouoldnt worry too much about the yellow cotyledons... you should just wait till they get their first set of leaves and give them a light light feeding... that should start making them strong and green