There are ample 4-inch (and many other sizes) plastic pots, left over from purchases at commercial greenhouses and maybe purloined from my father-in-law's shed (he was done with them). They just need to be washed clean of last (or some other) year's dirt and diseases. I did ten on the weekend; could have used a few more. We also had about two dozen small peat pots, barely larger than the wet pellets the plants are outgrowing. However, these will buy me a few more days until I get another batch of larger pots ready. Suppose I will need more potting soil, too.
It wasn't just the height of the stalks that drove me to pot up. The roots of some of these creatures obviously had greater expectations than life in a fibre pellet. The zucchini roots were headed for the far end of the tray. This is a problem because the roots start checking out other pellets and then the herbs, lettuce, and cauliflowers have to share their water with these goliaths. Actually, it probably does them no harm. It's easy to keep the contents of the tray sufficiently moist. However, the zucchinis might suffer when it's time to separate them from their neighbours. Roots growing through other pellets can't be removed intact. I had to break quite a few today.
They always seem to look a little worse for wear after being handled, pressed, showered with soil, and waved about more vigorously than they are accustomed to. The tomato plants all have siblings that were left in pellets. I'm looking forward to seeing what the difference is between the two environments after a week.
The exodus has made space in the trays for more pellets. Some insurance specimens, some seeds I have saved from last year, some different varieties shared by another urban farmer. Then more potting up. Good thing this gives me joy, joy, joy, joy down in my heart. The seedling collection takes up more space after being potted up. We assembled the mini greenhouse (a set of shelves with an optional plastic enclosure), after shaking snow melt out of the tubes and wiping crusty spider webbing from corners. A cardboard box, waterproofed with a garbage bag, holds all the upgraded plants, and the two trays sit on another shelf in front of the west-facing living room window. The south window in the attic might be better, but that would require rearranging furniture. One thing at a time.