Depends on how big the seedlings are and how close you are to being able to plant them out. There is a school of thought that some plants' root systems benefit from being transplanted a time or two.

Yes, if interested in reading them you can find many previous discussions on this question if you search 'potting-up'.

Since we grow a great deal of plants for sale, potting-up or "staged transplanting" is mandatory so I am big advocate of its benefits having seen them first hand for years. All those benefits are explained in great detail in those other posts so I won't re-hash it all here.

Your broccoli and cauliflower might make it (broccoli can be planted out now or within a week anyway, cauliflower needs a couple more weeks) but in your zone you still have over 6 weeks before you can transplant your tomatoes/tomatillos to the garden and 8-10 weeks before the peppers and eggplants can go out. So unless you already have them in at least 4" pots I honestly don't think you are going to have any choice. They will be extremely rootbound by then otherwise. Sorry.

But you don't have to invest in pots. Many just use the 16 oz. plastic drink cups, or plastic butter dishes, or the bottom half of 1 liter pop bottles (see 'containers' discussions here). Lots of containers will work as long as you put several drain holes in the bottoms.

Dave

Dave,

Thank you. I read a post on March 15 on the tomato growing forum where you gave an excellent explanation, which I found very helpful. I will start with 5 oz. cups and move to larger cups, if necessary.
I have 2 other questions, should I continue to use seed starting soil when I transplant and should I start fertilizing with a weak fish emulsion?
Thanks,
Michele

should I continue to use seed starting soil when I transplant and should I start fertilizing with a weak fish emulsion?

That's a bit of a gray, multi-opinionated area. Since you have done some reading you already know that I'm not big on supplemental feeding of young seedlings and consider it risky. Once they develop a second set of true leaves, fine as they will need some. But many others disagree with that position so it's up to you.

Basically it all depends on what soil mix you are using. If it is one that already has added nutrients then its fine. Since I use ProMix BX and it has some mircros in it I don't need to change. If not, then it's best to move on to a growing medium of some kind. Or if only doing a few plants then use your nutrient-free mix and feed them a diluted 1/2 strength feeding once a week or so.

Keep in mind that while fish emulsion is great for established plants in the garden, it isn't all that micro-nutrient inclusive or balanced when dealing with young seedlings (not mention it can stink up the house ;) so if that is what you prefer to use you might want to mix in some additional micros.

Bottom line as hoosiercherokee always says on the Tomato forum - watch your plants and they will tell you what they need. :)

Dave

I'm still very new to this seed starting, but last year I repotted 1/2 my tomatoes (I overplanted big time). The remaining ones I left in the 9-pack starting cells. What a difference. The ones I left in the 9-packs were stunted while the others really took off.

I just finished repotting my peppers, tomorrow the eggplants. I got smart this year and only started as many tomatoes as I needed plus 1 extra for each in 4" pots from the beginning.