Well, four points immediately come to mind. The first one you've partially already covered, but even fresh, good-quality seeds have only a certain maximum germination rate. So, If you plant only one seed per large container, you may end up with some blank containers. Optionally, you could plant a few seeds in each large contain and then thin down to one per pot, but this could waste seeds (and isn't it heartbreaking to have to throw those cute little seedling out).

A second consideration would be akin to the first. If you did plant more than one seed per container and then throw out the extras as they sprouted, you'd not be making the best use of your seeds. In cases where you only had just enough seed or few seeds, that might make the large-pot method too inefficient for your seed supply.

A third concern would be available space and available light. If you are starting your seeds indoors in winter or early spring, you may not have room for a bunch of big pots. But, you probably would have room for one big tray.

Finally, when growing a small seedling in a big pot, it may be harder to maintain proper moisture levels and moisture level cycles. I big pot full of soil is going to stay wet at lower levels longer than a smaller volume of soil, AND, the top of the soil (where your tiny seedlings roots are at) may dry out way prematurely. Different situations will be different, but moisture levels may be an issue of concern.

P.S.

I do what you are proposing often (especially planting a few seeds per container and then thinning), so I am not saying not to do it...just giving you the negatives.

Brandon, thank you for your answer. I have actually calculated the number of pots I can have (48) given the size of the pots, tray, and light area. I was going to increase the amount of perlite to help with water movement within the pot because I plan to water by mat, but the water deal is a concern. I have 2 extra pots, I may experiment with them to see if the bottom watering is going to get to the top as I hope. I appreciate that you pointed that out to me.
I planned 2 seeds per pot to make sure I get a plant in every pot. Although I know multiple plants in a pot is not ideal, you make a good point about how difficult it is to throw a healthy seedling out.

In addition to the negatives already listed you also lose the benefits of potting up and the burst of fibrous root development doing it triggers.

If you have read through any of the many 'potting up' discussions here and on other GW forums you'll recognize that it is a pretty big negative effect, skipping that step.

Dave

I start almost all my seeds in a flat not too deep container and then transplant to individual cells or pots. I use the shallow plastic containers that you buy mushrooms in. I have put drainage holes in the bottom of them with a wood burning tool.

The trouble with planting in pots is they are too deep. The top dries out and it's still wet on the bottom. You water to keep the top moist for germination and the fine new roots and before you know it the pots are water logged. Besides you can't put them under humidity domes because they are too tall. The mushroom boxes fit just fine and I can get 8 in a tray. I sow them thinly so the roots don't get entangled but if a few do I soak all the soil off of them so I don't damage the roots. Then they separate easily.

I find doing it this way is easier than trying to get 1 seed in each little cell of a 72 cell tray. Besides that I do the ones that require more root room in 6 or 4 packs so they can grow on with the required root space

I find doing it this way I lose very few plants.

I know lots of people advocate starting in a flat, then transplanting, but my fat fingers always seem to screw up something.

I've usually a double handful of Calendula seed more than I need. I just plant a big pinch in the pots where I want them. Thin out some surplus seedlings.

I would not do this with expensive seed, but where on has a surplus, why not.

Dave I saw a reference to what you are saying in one discussion and was unable to find other discussions, I will do a search under fibrous root thank you.

Found them, and it looks like I'll be going to Home Depot to get seed starting stuff and then transplant into my pots. Thanks Dave :)

Lucille, if you found other threads particularly useful, could you post links to the ones you found most important? I'd be interested to see just what they said.

In my experience, whether more fibrous roots are better is not necessarily a one-size-fits-all kinda thing. More fibrous roots are probably better in many cases and especially where the plant will be permanently grown in pots, but occasionally there may be disadvantages (probably more technical than I want to go into here). Another things is that you don't have to change pots to get the same results.

Like before, I am not saying that you should only do it one way (or in this case avoid a certain way), but am just trying to present some things to consider. If you are able to post the links, maybe we can get an even better handle on what needs to be considered.

P.S. If you grow your seedling in flats, do remember to pot up in time. Separating out overgrown seedlings whose roots have significantly intermingled can be a little bit of a mess and may even result in extra root loss and set-back.

Brandon, just doing a search for 'fibrous roots' and 'potting up' brings up quite a bit.
I will for sure move them prior to their roots getting entangled, thanks for bringing that up.