I'm curious if I'm doing my lighting right for my seedlings. I have
one of the Professional Jiffy Greenhouse 72 peat pellet seed starting
kits, and I'm starting my seeds for my garden.

Anyway, I have two 18" flourescent fixtures- one with a GE Plant &
Aquarium tube, and one with a GE Chroma 50 tube. I set the
fixtures/tubes directly on the plastic greenhouse top, and rotate them
each day, so that the plants get an even mix of Chroma 50 and Plant &
Aquarium light.

The vast majority of the seeds sprouted quick, and are growing madly-
most of them have their cotyledon leaves & stems almost to the top of
the plastic greenhouse top- they look kind of spindly right now. No
true leaves have shown up yet.

Is this a problem, or is it common for the cotyledon leaves to shoot up
really high and quick? I read that lack of light will cause leggy
plants, but I'm not short of light with my setup, am I?

In article .com,
"Mark" writes:
|
| Is this a problem, or is it common for the cotyledon leaves to shoot up
| really high and quick? I read that lack of light will cause leggy
| plants, but I'm not short of light with my setup, am I?

The usual cause is too much heat relative to the light, which is
a nightmare in the UK - we can get leggy seedlings OUTSIDE in
extreme circumstances!

Try keeping them cooler, at least from when they start to emerge
from the compost.


Regards,
Nick Maclaren.

Mark wrote:

The vast majority of the seeds sprouted quick, and are growing madly-
most of them have their cotyledon leaves & stems almost to the top of
the plastic greenhouse top- they look kind of spindly right now. No
true leaves have shown up yet.

Is this a problem, or is it common for the cotyledon leaves to shoot
up
really high and quick? I read that lack of light will cause leggy
plants, but I'm not short of light with my setup, am I?

you are definitely short of light. the other pieces of advice are
pretty good, and they will improve your light efficiency and prevent
damping off, but they won't solve your main problem, which is too
little light. You can evaluate things yourself. In full sun, with the
sun overhead you get about 600W/m2 of light. With the sun at 45
degrees, you get 420W/m2. Each 72-cell tray is about 0.18m2, so you
should be coming in with close to 80W/tray. Those fluorescents are
fairly efficient, but they are not 100% efficient, so make that
100W/tray. I found that the only thing that helps is a sunny window,
and taking them out to full sun as soon as feasible.