View Single Post
  #1   Report Post  
Old 26-06-2015, 03:57 AM posted to rec.gardens.edible
~misfit~[_4_] ~misfit~[_4_] is offline
external usenet poster
 
First recorded activity by GardenBanter: Nov 2014
Posts: 149
Default Winter tomatoes grown under lights...

... will remain just a dream for me it seems.

Once upon a time in another life I grew certain medicinal herbs under
artificial light (and subsequently got sent to prison for it). Back then the
accepted way was to flood the area with masses of light, even if it wasn't
the right spectrum. As long as you supplied enough of it the plants did
well. Either High Pressure Sodium lights or Metal Halide, whatever gave you
the brightest light per watt.

Flowering was simply a matter of adjusting the timer to shorten the
photoperiod and, voila! A week later the plant starts flowering. It was as
if I was the plants God, I controlled them completely. I grew in soil mixes
of my own crafting as well as experimenting with hydroponics and even had an
aeroponic system for propogating cuttings. I was very successful having
always been a 'greenfingers'. However the electricity bills were massive (as
was the impact of imprisonment on my life and health).

Fast forward a few decades and I'm an invalid on welfare growing what food
my pain allows me to (as only the rich - or at least moderately well-off can
afford to buy tasty nutritious fresh fruit and vegetables). I've always been
an early adopter of technology (when I can afford to) and my home lighting
has become all LED, moving on from the CFLs I was using since they first
appeared on the market decades ago. The savings in running costs soon cover
the outlay if you buy carefully.

I got to thinking; Light can not only be produced for around 10% of the
electricity cost it was when I grew under lights but also you can also
essentially select exactly what spectrum you want with LEDs. That means that
you don't need to emit the ~80% of the spectrum that plants *don't* use so
the cost reduces by a further 80%. That means it's possible to provide a
plant with all the light that it needs for less than 5% of what it used to
cost back in the bad old days.

(http://www.dx.com/p/202185 and http://www.dx.com/p/371209 is one of the
cheapest ways to produce a good growing spectrum. There are other emmiters
and drivers available on that site and others. All you need are basic
soldering skills and a heatsink to fix the emmiter to. It doesn't have to be
a big one as that driver is under-driving the LED, only giving it half of
the amps it is rated for so it's producing far less heat than at rated
power.)

I bought a few LED emmiters targetted at plant requirements like the above
and have used them over my aquarium with amazing results. Plant growth is
rampant - but the spectrum isn't that nice for a decorative aquarium. As I
had such bad luck with my tomatoes last summer (I'm in NZ so it's mid-winter
here) and I have some emmiters and drivers spare so thought to grow a cherry
tomato plant under lghts in a built-in closet in the spare room. I had some
seed saved from a couple years ago.

So I used up a good portion of my 'low-pain' time over the last few weeks
building a frame to hold the LEDs (I added a couple of 3w white LEDs to fill
out the spectrum) that hangs on light chain up to two hooks (easy to adjust
the height link-by-link) and germinated some seeds, selecting the best. Now
the plant is a couple of feet tall, thick-stemmed and with dark green leaves
and producing it's first flower spray, looking good! Except.....

Only now do I read a bit about growing tomatoes under lights (oh the
arrogance!) and discover that, to produce fruit they need daytime
temperatures above 17º C, ideally closer to 20º C. I mentioned I'm poor? I
can't afford to heat my home, LEDs have revolutionised lighting but heat
still costs big bucks. (It's 2pm and I'm currently sitting in a 13º C room
with lots of layers of clothing, my bedroom was 7º C at 7am yesterday.)

I have a thermometer in the closet with the the plant and daytime temps have
been in the very low teens lately with nightime temps dropping to single
digits. What little waste heat there is from the LED and power supplies is
raising the temps in the closet somewhat above ambient but nothing like the
masses of heat that *had* to be dumped from grow areas once upon a time. It
seems high-efficiency lighting can be a double-edged sword.

If I can't afford to heat my living space there's no way I can afford to
keep my tomato plant cosy and warm - even if it's in a very small space
(about 3' by 2' and 6' tall - but uninsulated). However after all the
trouble I've gone to I night try to heat the space to ~18º C for four or
five hours a day - *if* I can devise a small heat source for the job. (I
have a spare thermostat http://www.dx.com/p/234991 I just need a ~200w
small-footprint heater but for the life of me can't think of something I can
re-purpose for the job. It's not as if I can afford to buy anything more for
this experiment.

Anyway, maybe a bit off-topic for this forum but I thought I'd share. Wish
me luck!
--
Shaun.

"Humans will have advanced a long, long way when religious belief has a cozy
little classification in the DSM*."
David Melville (in r.a.s.f1)
(*Diagnostic and Statistical Manual of Mental Disorders)