I got an urgent email a couple days ago with the subject header: too many seedlings. The text follows.
I'm right across Route 2 from you (in Arlington).
I've got three Jiffy trays of seedlings going.
Two trays are still unsprung for the most part, but 1 tray is sort of exploding. It looks like a chia pet, and it is only 5 days old. It has Kale, Romaine, Bibb, Cabbage, Broccoli, and something else I can't remember.
Rather than thinning each cell out, I'm tempted to try to transplant some of these directly into the ground and see if they tough it out. I have so many plants in each cell, that I definitely have seedlings to spare.
Do you think it is worth the effort? Will they die in this cold snap that we're in the middle of?
Any advice would be much appreciated :)
This morning I wrote back. Here's my response.
I've been putting my seedling trays out in my cold frame for a few weeks and they're doing super. I put them under lights ‘til second or third leaves appear, then harden them off by putting the seed tray in the cold frame. When the plants outgrow the pots, I transplant close in soil inside the frame. I'll transplant them again in May at proper spacing out into the garden. This is working good so far, with limited electric light use and no bringing plants in and out to harden off.
I think it may work well for you to transplant now into a very sheltered spot. I'd put up a plastic tunnel of some type. Maybe small hoops and some clear plastic well secured by burying the edges in the soil. Make sure its in full sun. It would be best to assemble and leave it a day or two so the sun can warm the soil a bit. Then put your trays inside for a few days to harden off, prior to transplanting. Then transplant seedlings on a warm day. Lettuce and the other types of seedlings you mention are all very hardy. (You can plant with close spacing if you need to conserve tunnel space and then space out plants later when the covers come off.) You could use fabric row cover instead of plastic if you want. It’s a matter of guessing the weather. I think in mid April I would say to go with fabric row cover, but best now is plastic for 2-4 weeks then convert to row cover. I also like to have a cheap remote thermometer inside any plastic covers, because the sun even now it can overheat inside. When temps start to exceed 60*F or so, open the covers a bit for airflow.
I hope you don’t mind if I post this on my blog. Maybe others will add their advice.
Also this morning, I noticed another "neighbor" of mine has seedlings growing under plastic now. They don't even have hoops, but it seems like there are happy seedlings growing underneath. I always love to walk by this raised bed, which is right in the middle of their front yard! Super!