I don’t know why I was so skeptical about the milk jug greenhouses.  They have succeeded well beyond my expectations, and through a week where we had everything from 38 degrees and rain to 85 degrees and super gusty wind.  My brussels sprouts seedlings, which I started inside, have now been out in the garden for one entire week.  I put in six plants with the milk jugs, and had 4 leftover seedlings so I just put those in too, partially as a “control group” and partially just in case one of the milk jugs ones died.  One week later, a comparison:

Brussel sprout plant, without any protection:

Brussel sprout plant, with a milkjug greenhouse over it for its first week outside:

Now I just have to decide when to remove the greenhouses permanently.  It will have to be soon or the plants will get too big to fit inside.  Hoping for some milder weather tomorrow (we’re back to low 40s and rainy today).

To make a milk jug greenhouse: simply cut off the bottom of a milk jug, unscrew and discard the cap, and place it over your newly-transplanted-to-the-outside-world seedling.  Leave on until the weather improves.  But watch out if it gets too hot; you may want to remove it during the hottest part of the day so you don’t fry your plant.

I will eventually have to remove those four “control group” brussels because I don’t have room for them at full size.  If they survive and seem healthy enough, I’ll try to find a neighbor or friend who wants them.