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snappyguy

Lighting question

snappyguy
14 years ago

With winter coming and my violets being in a north-facing window they weren't getting enough light. I just installed 2- 48 inch 40W Phillips grow T12 fluorescent tubes for a total of 80W. They are about 16 inches off of the plants. My light meter says the plants are only getting about 100 foot-candles of light. Does this sound right or is my light meter giving a bad reading?

Thanks,

Mark

Comments (17)

  • rambler24
    14 years ago

    Mark,
    Im not sure about your light meter as I have never used one, but I have used the exact same set up as you with my plants around the same distance away for a few years now. I have my violets under the lights year round and they have thrived.

  • fred_hill
    14 years ago

    Hi Mark,
    I have been using 40W cool white bulbs for my av's for many years now and I keep the tops of the plants about 12 inches below the bulbs. I keep the lights on for 10 hours but when I am preparing them for show, I increase the length of time gradually by one hour till they get to 12 hours.
    Fred in nj

  • bspofford
    14 years ago

    Hi, Mark,

    I checked a couple of my books for foot candle requirements, and apparently 100 or less is not sufficient for blooming. They recommend about 800fc. Anything higher will scorch leaves, etc.

    I have my lights about 12 inches from the top of the plant (standards) to the tube, and it works well. 6-8 inches for minis is working well also.

    You may want to re-measure with a 12 inch distance and see what you come up with, and adjust accordingly.

    Barbara

  • snappyguy
    Original Author
    14 years ago

    Thanks everyone for your responses.

    I ordered a higher quality light meter that should be in today. My old meter reads 500 foot candles at about 1 inch from the bulb, which doesn't seem right, so I'm guessing I have a faulty meter. People seem to have success with very similar set-ups to mine, and that also makes me think the meter is bad. We'll see when the new one comes in.

  • snappyguy
    Original Author
    14 years ago

    Got my new light meter today and the old one was just a little off. I have 120 foot-candles (1300 lux) of light. AVSA recommends 10000-20000 lux of light, but others here seem to have luck with the same setup I have. My meter works best in the yellow light spectrum, so I wonder if it's under measuring the red and blue light needed for violets. Any ideas about this and how to change my lighting if necessary?

  • robitaillenancy1
    14 years ago

    You could lower the light closer to the plants (12 inches in normal) or you could put something under each plant so it is closer.

    My lights are 12 inches from the top of the standards. With miniatures and semiminiatures, lights should be about 4-6 inches from the tops of the plant.

    Lights should be on 10-12 hours a day. If you take plants to show, light hours should be increased hour by hour until you reach a maximum of 15-16 hours per day.

    Growing To Show by Pauline Bartholomew is a book that can be bought from AVSA. In this she explains about lighting.

    If you grow only by window light, try another window. I live in Montreal, Canada and plants are in the west window. Depending where you live you could try other placement. Plants should be about 12 inches away from windows to protect from direct sun and from drafts.

    Nancy

  • korina
    14 years ago

    Yeah, what Nancy says. (Hi Nancy!)

  • snappyguy
    Original Author
    14 years ago

    How many bulbs are people using and do you get blooms all year long? I only have 2 bulbs so I wonder if people are using more because I can only get 10000 lux at a couple centimeters from the bulb.

  • quitecontrary
    14 years ago

    Mark -
    I am wondering about the Phillips lamp you mention. Is it Coral Grow? I think Phillips makes some aquarium lighting - so who knows how much light those produce. As previous posters have explained, the standard light setup for AVs is 2 40-watt T-12 fluorescent tubes placed approximately 12" from the tops of standard-size AV plants. When I had Flora Carts, I used either two cool white tubes or one cool white and one warm white. I did not like the expensive grow bulbs as the light they put out was pinkish in color. Also, I never noticed that they worked any better than plain, cheap bulbs. I think the cool white tubes produce more light than the other tints. If your plants are getting enough light, they will tell you so in short order. The leaves will lie flat, and they will bloom frequently all year long. Good luck with your new setup, and let us know how it goes.
    QC

  • snappyguy
    Original Author
    14 years ago

    I'll try lowering my lights to 12" over my standards. The bulb isn't coral grow. It's sold as Plant and Aquarium by Philips. I'll definitely let you know how it all goes.

  • bspofford
    14 years ago

    I use one warm white and one cool white in each fixture, as this gives the complete spectrum.

    Barbara

  • orchidnana
    14 years ago

    This is also what i use 1 cool and i warm,seems to work ok

  • Coralred
    14 years ago

    I am using two T5 32W lights, the AVs I place them about 15cm away from the light and they are doing well.

  • okie_deb
    14 years ago

    I'm using the plant and aquarium bulbs (1 per shelf) and getting new bud stalks and so far 1 AV has flowered. I have the plants about 6-7 inches from the leaf tops on the semi and mini's.
    I'm new to growing AV's so I will have to see if this works as days get shorter and the room cools with winter. Lack of flowers or leaves reaching upwards will tell me I need to revamp.
    I have used the warm with a cool florescent in the past with my Hoya's. But in the zip greenhouse the double bulb fixture I thought would be too bulky so I went the single bulb way.,,,Debbie

  • snappyguy
    Original Author
    14 years ago

    I think the leaves are starting to lay back down so I think I have enough light. I still need to lower the lights some, down to 12 inches. We'll know better when we start seeing lots of blooms.

  • curtis0353
    14 years ago

    I use 1 cool and 1 warm 40 watt T-12 tube in my shoplights and when testing with my light meter I get a reading of about 1200 footcandles when touching the tubes with the meter and about 650 footcandles at about 10 - 12 inches below the tubes where the tops of my plants are. I get weaker readings at the ends of the tubes, somewhere in the 450- 500 footcandle range at plant level. It is amazing as to how many footcandles you lose the further away from the tubes you take your measurements. I use my light meter to get a general reading to help me decide about possible plant locations at various windows in my home, but in the end I usually let the plants tell me whether they are happy or not with the light level. If the leaves are growing upward they are usually asking for more light, and if they are cupping down over the edges of the pot they are probably getting too much.

    Curtis

  • okie_deb
    14 years ago

    Thank you Curtis for explaining what violets do with too much light. I didn't know on violets. Good thing to store in my brain and watch for!,,,Debbie

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