I'm attempting to grow Curcubits and Nightshades (for eating) indoors (in the middle of winter). I recently acquired a (Red/Blue LED 120 watt) grow lamp - but my calculations are that it will eat a lot of electricity for the number of seedlings it will produce. [ I'm growing everything in a 60cm x 40cm x 35cm high with my lamp situated about 10cm above the lid ]

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Am I better off having this light come on intermittently throughout the day and night to provide warmth and heating, or have it on a timer - say 4 hours per day, and rely on heating from a heat pad (actually a heating blanket under my plastic growing chamber) ?

(Unless it is not practical to avoid it, I would prefer not to leave the light on for 12 hours per day as it seems it will eat quite a lot of power)

I guess a third option would be to remove the heat pad and rely on the Light, but I think this would be inefficient for heating.

Does anyone have any ideas how best to optimise the setup of my "growing container" ?

  • 1
    LEDs should not produce heat. Night rates of power are a lot less then day time. I pay 5c kWh at night. So if I were to run your light, it would cost less then 5c per 8 hours. – Graham Chiu Jul 30 '16 at 5:34
  • These LED's definitely feel warm on my hand. This is not producing anything like as much as a 120 watt incandecent (or even a 60 watt one), but there is definitely heat. I pay a flat rate of about 17c / kWh 24/7 - and I don't think I have a choice of a day/night rate here. – davidgo Jul 30 '16 at 7:03
  • The electronics should be warm, but the light is cold. Check out flick electric for their pricing model. – Graham Chiu Jul 30 '16 at 7:28
  • btw; blue is for vegetative growth, red is for reproductive growth when one actually gets to the point of playing with light and dark time schedules to force budding. Plants should not have light 24/7, never. To start out with 18/6...then when you want flowering 12/12 or depending on the normal light/dark schedules for the individual species of plant. Go get solar... – stormy Jul 31 '16 at 3:04
  • @davidgo I just noticed the plastic lid is on so reducing the light intensity considerably! I see the reflection of the lights. You need to remove that lid and suspend the lights above the seedlings. – Graham Chiu Aug 1 '16 at 8:19

You don't need light. In fact, it is also frequent to cover seeds with paper, in order to have stronger seedlings.

After the cotyledon stage, light is good, but I think that sun is enough (and more powerful then lamps, also in winter). In my opinion the temperature is more important.

  • Giacomo, please edit your answer - I've got a new laptop with touchscreen and seem to have downvoted your answer, and it wasn't intentional. I now can't change it unless you add, delete or edit something in your answer! Ping me when you've done it please.... – Bamboo Jul 30 '16 at 17:05
  • @Bamboo Hi! I've done that with my touchscreen before too, and it's frustrating. Very smart of you to ask for an edit. Giacomo, I hope I didn't overstep, but I made a minor edit to the answer, so Bamboo should be able to change her vote now. I already did my upvote! – Sue Saddest Farewell TGO GL Jul 30 '16 at 18:28
  • Plants need heat to germinate, but primarily light to grow. – Graham Chiu Jul 30 '16 at 20:19
  • @Sue - thanks, must remember to scroll up and down on the right of the screen, not the left! – Bamboo Jul 30 '16 at 20:31
  • Plants need heat to germinate, not light. Once germinated, light needs to be added! Graham, yes, you said the same thing. I couldn't imagine worrying about cost of lighting over my plants. Once one learns the basics then they can deal with costs. But to get plants growing well is far more important. My opinion...it always costs money to learn to grow and keep plants vigorous. Part of getting educated in Botany. – stormy Jul 31 '16 at 2:59

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