How big are the containers you planted them in? At this point in time, you could put the seedlings at an early stage into a 4" pot and they will be fine till it's time to plant out when the weather's warm, which should be in a month for you. You might even be able to plant out directly from your present container since it's only a few weeks and the plants will be small.

I planted my tomato and pepper seeds in one of those self-watering seed trays that you should have started flowers in.

There are many of these and all are different so please give us the measurement/size of the cells they are in for the most accurate answer.

As Susan said, transplanting (deeply if needed) in 4" plastic pots is pretty standard but depends in part on the size they are currently in.

Dave

The cells are 1 3/8 inches square and 2 inches deep. Its a Burpee seed starting, self watering kit with a plastic "roof." My seeds just started to sprout yesterday, they have only been in for 6 days.

I am growing them in my office under my flourescent desk lamp. I am not sure how long they can stay in the seed starter before I have to transplant them.

Silly question, but are these 4 inch pots the kind you plant into the ground?

The cells are 1 3/8 inches square and 2 inches deep. Its a Burpee seed starting, self watering kit with a plastic "roof." My seeds just started to sprout yesterday, they have only been in for 6 days.

I am growing them in my office under my flourescent desk lamp. I am not sure how long they can stay in the seed starter before I have to transplant them.

Silly question, but are these 4 inch pots the kind you plant into the ground?

You'll have to transplant them. 4" pots are any plastic pot/cup with drainage holes in them. Next year you can start them in bigger cell paks. At this point in the growing season, you can transplant them into 3" pots because you'll be planting them out soon. They sell these pots in packages at nurseries. Over the years you can collect a lot of pots and cell paks and reuse them.