Hope you don't mind if I first link to your previous post on this question since it has some info in it already.

You indicate in it that your zone is 6B correct? If so you really need to add that to your sign in (see how we all have our zones listed by our names.

Then someone asked in the other post what seeds specifically you are talking about? We still need that info since all seeds are treated differently. So what seedlings are we talking about? Some will tolerate full sun exposure, some will require a bit of shading to keep them from burning.

But basically, in very general terms and with several exceptions, you just control the temperature. And with mixed vegetables that may be difficult to do without some shade-type covering. For example young lettuces and other leafy greens won't tolerate near the same temps as tomato and pepper plants will. Leafy greens require cool growing temps once they germinate.

So this first year, depending on how your cold frame is built (not to mention the excessive warm temps we are having this year) you will be doing a lot of experimenting, trial and error learning, to discover how your cold frame works.

You mention both lettuce and spinach in the other post. In zone 6B those should already be out in the garden several weeks ago since it is rapidly becoming so warm they are already starting to bolt and go to seed.

Hope this helps.

Dave

Tomatoes and peppers are in the cold frame currently. So the sun will not be too strong for the seedlings when they first emerge since I started them in the cold frame?

Strictly speaking this is not a cold frame as you use a heater. With both a heater and a fan you should not have any problems, but make sure you don't overdo it, the combination could dry the seedlings out very rapidly, especially if the area is small.In Arizona you will only need to use them on the coldest nights. During the day I would leave it open. - Ian

So the sun will not be too strong for the seedlings when they first emerge since I started them in the cold frame?

There really isn't anyway for us to know for sure since we don't know what your sun exposure is in your cold frame. Usually, no but you will have to watch them closely at first and any sign of sun scald or fast wilting etc. then you'll need to move or cover them with shade.

Right now, here, it is in the 80s in the day time so any seedlings in a cold frame in the direct sun here would quickly die. Even the greenhouse already has its 80% shadecloth on to reduce the temps and prevent sun scald. I'd suspect that your cold frame would have to be wide open all day right now.

Dave