On Jun 16, 10:28 am, Billy wrote:
I was wondering if anyone else had the same observation as I have.
I use a soil that is specifically for germination (high sphagnum
moss content I think) and it seems to do a good job of germination
but then the seedlings seem to lack vigor. When I transplant the
seedlings into larger vessels with "regular" potting mix, the
plants suddenly become vigorous.

Anyone else have this experience?

To some degree yes. After moving to a new home, I've been trying to
establish some new California poppies late in the season. I saw
almost nothing growing from seed this late. I eventually tried
Jiffy-7 "peat pellets" which are primarily sphagnum moss as well as
square peat pots with potting soil (Miracle-Gro Moisture Control).
The seedlings (germinated indoors) coming out of the pots (soil
moderately packed) come up more slowly and smaller, but they seem
stocky and strong. Most of the seedlings from the pellets are growing
taller, but spindly with long stems sticking out underneath the base.
One reason may have been when I kept them too long indoors. They
seemed to get longer stems because they grew and leaned towards the
sun coming from the window. Another part could be the fertilizer in
the potting soil as well as the resistance to root growth from the
packed soil. I move them outdoors to condition them to the sun, but
some seedlings have died from the heat. I guess that's fine, since
I'm trying to develop seedlings that won't just die when they get
transplanted.

I did have one really nice example growing from a pellet, that I've
since transplanted to a pot. That one I germinated in a different
area, and took it outside as soon as I saw the taproot well
established and before the stem popped up.

I have removed the netting from the pellets before transplanting. The
peat pots I've watered and pulled back to keep the soil around the
seedling intact. I've used plastic seedling pots, but I have a hard
time getting them out without damaging the root. I also tried ripping
the used peat pots into pieces to use as a soil amendment.

Just for fun I'm trying to sprout up some heliotropes from seed in the
peat pellets. I'll see how that turns out.