I started cucumbers from seeds in those peat pellets that expand when water is added. The seeds grew voraciously for the first week or so, but now they haven't grown significantly in about three weeks. I discovered that I had been overwatering them, so I moved the peat pellet, which had been in pure potting soil (in a container) into a rendition of the 5:1:1 mix, only using pine bark fines that made it through a 1/16" sieve. I think the pictures tell a better story than I can. I'm growing under an 800 W LED fixture, by the way. Note that these are all different cucumber plants. Thanks!