Tomatoes will set new roots on their stems and this will establish a hardier root system. For peppers; only plant them at ground level. By now, you have needed to remove the plastic cover on top and will need more space for your pots. It is best to still water your plants from below if possible. Keep the lights on or move them into a bright sheltered place. Tomatoes and peppers are very sensitive to freezing temperatures, so you still need to keep them warm and cozy. They still need bright light and if not supplied they will weaken. Continue to water in the tray and allow the pots to soak up the moisture. Now is the time to supply a bit of fertilizer to the water; less is better than more. Use any kind of granular fertilizer that you have, orchid, houseplant, Miracle Grow used at half strength and throughly dissolved into the water. Apply it ONLY once, not on top but in the basin. Less fertilizer is worse than none. After all this care, it must be late April or May and your seedlings are now “plants”. Even if it is hot outside, we could get a spring frost which will kill these creatures, so get yourself a few “wall of waters” to house each plant. If you don’t want to spring for this, you can use bubble wrap, plastic bottles filled with water, ….use your imagination. It is important, to surround your new fledlings with a warm and cozy environment in which to grow. One other option is if you are planting them in pots outside, you can make sure that you can move the pots into a warm environment like a garage and back outside. Before you move them outside for good, they should become acclimated to the temperatures and the constant sunlight. This is called “hardnering off”. So, put them out for a few hours a day and build it up to all day, over the course of a week or two. Have fun and a great harvest.