Transplanted my first seedling out today. Probably way premature, but this little spinach is already ~4 weeks from seed (began life in the original LED greens experiment) and supposed to be mature at ~6 weeks. Painfully root-bound - those 6-packs aren't deep enough for spinach. I started hardening them a week ago, and they got much happier every day out in the 40° clouds and rain. (Stayed in on the blizzard day. )
It's cold out. But assorted advice is to plant spinach, peas, chard, and lettuce 4-6 weeks before last frost. Which is supposed to be around mid-April. Currently, every night is below freezing. But not below 25°F. I wanted them to harden to sun more, but there's no sun forcast for the next 5 days, and that's typical of March.
Also planted seeds outside last weekend - spinach, peas, and chard. Unsurprisingly, none of those are up yet.
Will see how it goes with the spinach before trying to put out the lettuce. I think that should wait another week or two minimum.