A photo would help a lot but there are several things to say here even without one:

We don't know where you are based but in most places it is extremely early to be sowing seeds for planting out in the spring.

An egg carton is far too small for growing kale seedlings to transplant size. They certainly need potting up.

Indoor seedlings need a lot of light (I don't use lights so I can't tell you how much). They will definitely need plant lights.

You are right that the seed leaves fall of naturally - but the true leaves shouldn't be doing it at this age.

There is little point clipping off yellow leaves. Clipping leaves a stub which invites fungal infection and yellow leaves will fall by themselves.

If you can put a picture up I'm sure you'll get more information.

Hi thanks! Ok, I will transplant them into pots this weekend. Maybe that's the problem - the egg carton is too small. I have my camera charging right now, I'll get a picture tonight. I live north of Seattle - I started now because we never know what kind of spring we will have here, could be early though so I wanted to be ready. :)

Thanks!

Here is a picture. I hope it's clear (my camera is not a great one). Where the red bar is, is where a leaf has turned yellow.

Thanks!

It actually looks pretty good other than being a little leggy, presumably from a slight lack of light. I wouldn't worry about the yellow leaf.

I don't know much about your climate but here I would sow kale in late May for planting out in late summer. It's a winter vegetable for us.

Hi Pokeypuppy,

Well, your kale seedlings definitely need larger pots, as Floral has mentioned. As for the light needed, kale requires very little light actually; 500 or 600 foot-candles is probably enough. Keep in mind that kale is a long-day plant, meaning that it will tend to flower when the day length exceeds it's critical photoperiod (usually about 10 hours). Of course, you donâÂÂt want that :-)

IâÂÂve never grown kale seedlings, but if I did I would start with about 500 or 600 foot-candles for about 10 hours a day. You want fluorescent lighting that has more blue in the spectrum than red (red will tend to induce flowering also).

DonâÂÂt know how many seedlings youâÂÂre growing, so donâÂÂt know how many lights you need. But as an example, one four foot fixture with a couple of T8 bulbs (preferably 5000K or higher) would give you about 700 or 800 foot-candles when 6 or 8 inches above the seedlings. You could get quite a few kale seedlings under something like that. If the seedlings still tend to be a little leggy, you could lower the light a bit.

Hope this is helpful,

Art

Alternatively you could forget all the technical stuff about lights and sow them at a more appropriate time of year outdoors or in a sunny windowsill. I grow kale from seed every year and have never used lights.

One good thing is that leggy brassica seedlings can be transplanted much deeper and will root from the buried stem.

Just wondering how your kale was doing? My dad grows lot of kale.I dig some and pot them, grow some inside, needs plenty of root room, fed well, and does well.I start some from seed indoor, use PRO-MIX in tall skinny pots and don't have to transplant for a while.Like the others said, short days with right color light.