Do it now. If you wait, they will have their root systems all entangled and you will wind up damaging some or all of them trying to separate them. You maybe should have done it a week ago but I think you will still be OK now.
Bruce

Thanks Bruce! I picked up some potting soil yesterday and wanted to get a little feedback first!

Also, forgot to add. Is sterilizing the potting soil mix necessary by the way? I've found mixed emotions about it, and never have before really and haven't had any issues. What's your take on it?

ab2008: Here is an alternative growing process that you may want to consider. It looks to me you are using one of those 72 or 36 cell starter kits with about 1" cells. Instead of planting 3-4 seeds per cell and planning to separate them out later, I would suggest that you simply plant 2-3 seeds per cell and then plant as many cells as you wish to end up with for each type of pepper. Then as they emerge, simply snip all but the one in each cell that is the most vigorous. Chances are very high that by planting 2-3 seeds per cell will result in at least one germinating and sprouting. This will save you the work of separating them later and will also save the seedlings from the stress and possible damage of being separated. This is assuming that your seed supply will support this method.
Bruce

Thanks again Bruce, I initially put 3 or 4 per if I'm not mistaken, I wasn't sure how they'd do.

They were fairly thin at first, I took them out of my mini greenhouse and put them under light. A few days ago I received my seed mat and since then they decided to sprout just now. I will probably cut off the smaller ones.

With that said, when they are about that big or a little smaller I should probably move them to a larger type of cell/pot though? I'll probably move them over to my 18 slot seed tray since it has fairly large cups in it. Or just go get some cheapo 16 oz cups and use.

If you are going to separate seedlings, I would do it shortly after they start getting their first true leaves.

I have never sterilized soil. Some people are very adament about doing it. First of all, I figure it is already about as sterile or more so than any dirt outside in the garden. Second, I am too lazy to deal with it. Much, much too much of a hassle for the theoretical returns in my opinion.
Bruce

Thanks again. Usually I hadn't bothered with it too much with just my sweet peppers and such, but it does make sense to get them separated so I don't risk damaging the roots. Will probably head out and get them split up in a bit.

Amos

To tag on to Bruce's suggestion of planting the number of cells you want to end up with, and planting 2-3 seeds per cell and snipping the weaker ones.....

If by chance you end up with a cell or two that doesn't have any come up, hopefully, you end up with another cell of the same variety that has more than one come up and then you can use "plan b", and separate as needed to end up with the right number of cells. :-)

In other words, you don't have to choose between one or the other. You can employ both strategies if needed.

Hybrid approach. Yep, I have used that too. Good suggestion tsheets.
Bruce

heh, yeah, I basically described last year. :-)

Well I separated my habaneros out. Put 18 out, and discarded the rest. Used a mixture of some miracle gro potting soil + some composted cow manure. We'll see how it does.I considered using some bigger cups, but I had one of these spare trays and I really like them so I figured I'd use it.

How big are those squares?

tsheets,

Just a spare tray I had. The squares are around 3.5" wide x 3.5" length x 3.5" tall. It may be a little off but that's just my guess by looking at them without throwing a tape measure on them.

I don't have any cups at the moment that was suitable, so i just went ahead and used this till I can get something a little bigger for them. Mostly just wanted to get them separated out, and out of the 72 cell tray I did have them in.

Those will probably work fine until they're ready for their final homes.

You think so, tsheets? If they do start to outgrow them a bit, I will just go get some cups and put them in there. But these trays I do really like because of their sizes.

ab2008:
Those are the same kind of containers and trays I use. i use two trays with 18 - 3.5" containers in each tray. I am "hoping" they will be big enough until I pot up for the summer, but being in zone 4, I seriously have my doubts. You will probably be OK in your grow zone. My plants a week or so behind yours right now.
Bruce

Yeah it's kind of hit and miss where I'm located. I'm right on the line of 6 and 7 so it's sketchy at times.

Well, I can't put my peppers out full time until the end of May. I am sure you will be well ahead of me there.
Bruce

I've just moved most of my seedlings into very similar containers myself. I sowed 2 seeds in each cell, but almost all of them sprouted and I didn't have the heart to cull anyone yet (still lots of time for various plagues to hit my plants), so I've separated and potted all of them.

I found that it helps to let the seedlings dry out before separating them, as it makes it a lot easier to pull them apart without damaging the roots. I also intentionally sowed most of the seeds a bit apart as I suspected I would not be able to bring myself to killing the sweet little guys :)

My only problem now is that a few of the plants have grown quite a bit, and also got a little leggy under my initially poor lighting, so now they're too tall for the cups. I think I'll just pot those guys in some Yoghurt containers or something. FTR, I "buried" all my seedlings all the way up to the cotyledons, sometimes putting 2" of stem under dirt. Every single seedling are still doing very fine, I'd even say they're growing faster after I moved them into separate pots (also beefed up the lighting in the process - 5 30W CFLs now).

Really Bruce, you don't put your peppers out until the end of May? How do you get them to ripen with our short summers? Last year I planted everything except english cucumbers the third weekend in April. The year before was second weekend in May due to all the snow. I'm still debating when to plant faster growing plants.

Yeah, I use that size of "first potting" pot too. I like the square ones because the fit in the flat nice and orderly, and the local pot exchange (at Lowes) has beaucoup right now.

But I move into a 5:1:1 type mix (actually more like 5:2:1) rather than peat (MGMC) as in the past. I was skeptical that they'd like it with the small root structure at this stage, but they take to it like ducks to water.

I don't sterilize either (actually, pasteurize - take it to 160ðF). I don't see the need if you don't have a known issue.