How close do fluorescent lights have to be to indoor propagation trays to
be effective? I would like to use the ceiling lights I have in the
basement. If I were to set up a couple of sawhorses with propagation
mats, do you think I could get by with the ceiling lights, or will I have
to lower them to within a foot or so of the seeds?
Regular fluorescent lights need to be within a couple of
inches of most plants you might start. say, tomatoes. I'd give them 12
or 14 hours a day too. If they don't get enough light they'll get tall
reaching for the light but be very weak and skinny. Another problem
you'll run into is that as the plants grow taller and you raise the
light to give them room the lower part of the plant won't get enough
light, so you don't want them growing too tall under the fluorescent.
It's best to transfer them to a cold frame and sunlight as soon as you
can. Plants started under fluorescent must be hardened off carefully
when placed outside or the shock of sunlight will do them in. I've
started thousands of them this way but I'm now very happy to have a
metal halide light. It can be placed well above them and still get
plenty of light to the whole plant. It also allows for a very brief
hardening off period without even messing with a cold frame.
I will vary depending on what you are growing. I have a flat of
parsley seeds germinating under fluorescent lights. The tubes are
about 2" from the soil surface. Hang your lights on chains for ease
of adjustment--much easier than trying to adjust the pots and trays.
I start my plants with fluorescents every year. When I first tried this
(maybe fifteen years ago) I kept the lights 6-8 inches above the plants.
All those plants came up but quickly got tall and leggy - not good. The
second year I did the same thing with the lights but ran a fan on the
plants to help 'harden' them up. They all just fell over and still
became quite leggy. The next year I wisened up and put the fluorescents
right on top of the plants - within an inch. Initially I was afraid the
heat from the bulbs would hurt the plants but that's not the case at
all. I now use fluorescent 'grow' lamps which more closely mimic the
full spectrum of the sun. I also still use an oscillating fan to toughen
up the plants about two weeks before outside planting time. Just make
sure to properly 'harden off' the plants before you set them out in the
garden. Good luck.
On Mon, 19 Jan 2004 10:33:26 -0500, Navin R. Johnson wrote:
I have GE Chroma 50 lamps. Although these are not gro-lites, they do
approximate midday color temperature. I would guess these will work just
fine. They are also considerably less expensive than the lamps being sold
As close as possible. Maybe even closer. Not touching.
When I used lights for starting in the basement, I used two shop lights
mounted right next to each other. I could get 4 flats under the pair of
lights. I would set the flats on a stack of newspaper to place them as
close as I could to the lights. As the plants grow, you just take out
sections of newspaper to lower the flat. The newspaper absorbs spilled
water. The fluorescent bulbs are not as hot as incandescent, but they do
generate some heat. If a plant grows into the lamps, you have a half a
day to a day to get them out before they start burning (actually just
drying out, not actually catching on fire).
Some plants always got leggy anyway. I find that sunlight is far and
away the best way to start plants. Much better than lights (although I
haven't tried the high intensity greenhouse lamps). A couple of trial
runs will tell you which plants can be done under lights and which need
real sunlight (depends partly on where you live).
Another problem with starting plants in the basement is damping off.
This is caused by high humidity at the point where the stem comes out of
the soil. The humidity encourages growth of funguses that kill the
plant. If you place a fan in the room so that air circulates, this
reduces the problem significantly. You don't have to blow the air onto
the plants, just keep the air moving. Leave the fan on all the time.
For tomatoes, a common practice is "brushing" the plants. This is
basically moving the plants around by running a brush over them, first
one direction, then another. The mechanical stimulation of the stems
strengthens them and makes them thicker, so that they will withstand
wind better when they are transplanted outdoors. Once or twice a day. I
have around 50 flats of tomato plants. I use a leaf blower on them to
strengthen them. A smaller quantity of plants can be done easily by
On Tue, 20 Jan 2004 08:28:06 -0500, Dwight Sipler wrote:
Thanks for tip about basement germination and damping off. Unfortunately,
I do not have a southern exposure on my house. The building faces
east/west with only a small bathroom window on the south. Poor
construction design and lack of foresight by the builder, I know.
My idea was to put flats on propagation mats under fluorescent tubes in
the basement. Now I may consider starting seeds using whatever light
comes in from the west. At least the plants would get some sunlight.
I would still use the mats.
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