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hudson___wy

Tomato Plants & Darkness

hudson___wy
11 years ago

It is too expensive to heat our GH this time of year in our zone of 3. We decided to try planting the tomatoes in the GH under a frost blanket with 100 watt incandescent bulbs to keep them warm during the night.

We moved the plants from our grow lights in the house to the GH two weeks ago. The night time OS temperatures have been holding between 5-20 degrees Fahrenheit since we planted so it has been too cold in the GH (29-36 degrees night time) and I have not been able to turn off the bulbs to give them darkness.

Has anyone had experience with growing Tomato plants using light bulbs to keep them warm during the night? How long can the tomato plants survive without darkness? How much dark should tomato plants have? I have not been able to find much information regarding tomatoes and darkness on the web?

{{gwi:291795}}

Comments (10)

  • timmy1
    11 years ago

    Well hey!

    In alaska, during the summer, the sun hardly sets right?

  • hudson___wy
    Original Author
    11 years ago

    One would think so - but read the following from EHow.

    Photoperiodism
    Photoperiodism refers to a response in a plant to the changing length of day and night. It helps plants to pollinate and produce flowers. "Short-day" plants require short periods of light, while "long-day" plants require longer exposure. Tomato plants are "day neutral," which means their flowering cycle is not determined by the period of light to which they are exposed.

    Photosynthesis
    Still, tomato plants require darkness for the process of photosynthesis. Energy collected from sunlight is converted into sugars during the night hours. These sugars serve as food for the developing fruit.

    Light Requirements
    Although tomato plants can be grown under artificial light in greenhouses, they do require at least six to eight hours of darkness every day to ensure optimal growth............

    Having read this - experience from someone who has grown tomatoes with lights for heat during the night may have suggestions for success? It appears from the above information that seedlings (not producing fruit) may be OK without darkness - although growth may be a consideration?

  • MaryMcP Zone 8b - Phx AZ
    11 years ago

    When my little brother was growing a certain herb, he kept the lights on 24/7 until he wanted the plant to start producing buds (or fruit), then he switched to 18/6. The 24/7 light schedule went on for a few weeks - 6 to 8 maybe. Yes, eventually they need some darkness to make that photosynthesis stuff happen, but you do have some time to play around with it.

    Hope this helps somewhat.

  • cal_mario
    11 years ago

    Hi,29-36 degrees at night is cold but I have grown tomatoes in a bit colder temps for a period of time with no heat or light at night for added warmth and done fine in a hoophouse.I use heavy frost blankets also but also put a heavy black plastic sheet over that for double protection overnight.Good luck.

  • taboule
    11 years ago

    Hi, I leave the lights on 24/7 on all my seedlings and get amazing results. They'll get their periods of darkness once they go outside.

  • hudson___wy
    Original Author
    11 years ago

    Thanks for your comments! So far the light bulbs appear to be working - we are in a cold spell right now for this time of year. OS temperatures dropped to 2 degrees last night and projected lower tonight. The GH was 26 degrees but under the frost cover it was 46 degrees. If we can make it through this cold snap - I think the coldest temps for the spring will be behind us?!

    The tomato plants are growing - this is how they looked today. German Giant, Better Boy, Super Marzano, Brandy Boy and Sweet Baby Girl.

    {{gwi:291797}}

    Update: I hope I am not boring you all with this information but it is fascinating to me that light bulbs and frost blankets can keep tomato plants alive without heating the GH with -4 OS temps. This is what it looked like this morning - GH temp was 19 degrees - under the frost blanket was 36-37 degrees. It appears the tomato plants were protected, although I think -4 appears to be about the limit low OS temp?!

    {{gwi:291798}}

    This post was edited by Hudson...WY on Mon, Mar 25, 13 at 10:27

  • MaryMcP Zone 8b - Phx AZ
    11 years ago

    Everybody is looking great! Good job!!

  • timmy1
    11 years ago

    Right-o plants look fabulous!

  • hudson___wy
    Original Author
    11 years ago

    Apparently the night time lights are not preventing these seedlings from doing their thing! I went out to check on them today and had to dig higher supports out of the snow from 18" to 24" to allow them room to grow and the German Giant, Better Boy, Super Marzano and Brandy Boy all had clusters developing - yeah!

    {{gwi:293468}}

    This post was edited by Hudson...WY on Wed, Mar 27, 13 at 22:44

  • mule
    11 years ago

    According to the CRC Handbook of Flowering most tomato lines are not photoperiodic.

    Only a few lines have been reported to have problems with flowering when there are bright security or street lights nearby. But for the most part the effect is minimal. Especially at this time of the year for most varieties.

    The heat to keep them going out ways the set back that might occur from this brief period of uninterrupted light.