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Thread: Putting lights UNDER the plants to help bottom growth?

  1. #1
    420 Member
    Join Date
    Sep 2009
    Los Angeles

    Putting lights UNDER the plants to help bottom growth?

    I've got my 3rd grow (some Skywalker plants) starting flowering now, and I was wondering about adding extra lighting underneath the plants to help the bottom growth.

    My last grow I had 9 Granddaddy Purples, and they are a pure indica and get really bushy as they grow. The tops had nice buds and I averaged 1.4 ounces per plant without CO2, but the bottom buds were light and airy and small.

    I also had 4 Bubba OGs averaging a bit over 2 ounces per plant, and their bottom growth was smaller than the tops but not as small as the GDP.

    These Skywalkers are sativa / indica hybrid from what I'm told, so I don't think they will be as bushy, but I don't want tiny bottom buds again.

    My neighbor who grows has told me that bottom lighting will help a lot, and also trimming off the small bottom branches right from the start of flowering will also make the upper buds bigger.

    I was at Home Depot last night, and I can pick up some twin T8 4 foot light fixtures for $20 each, plus 2 T8 3000K 4' bulbs for $7. And lay them on the floor between the rows of buckets. So 3 sets of lights will cost me $81 + tax.

    Top light is a 1000 watt HPS, with a 400 HPS which will be turned on when the plants get larger.

    So would bottom lights be worth it with these plants?

  2. #2
    420 Member HeadMed's Avatar
    Join Date
    Feb 2006
    way out there

    Re: Putting lights UNDER the plants to help bottom growth?

    I have found that side lighting helps. but lighting from underneath was almost always wasted. Also I like to keep my lights away from water. A fan to gently move the plants constantly will help with penetration of light (and make for stronger stems).

    The top face of the leaf has the majority of solar active cells, while the bottom side of the leaf has the majority of (stoma?) (small holes opened and closed to vaporize gasses out of the plant, and absorb moisture back into the plant.)

    I have had good results with t12's along the walls around the sides of the grow. The 4' tubes (t8's should be even better, less watts = less heat) if you use the plastic bulb tubes (sold at hd to protect tubes like that need commercially for code in some areas), to protect plants that end up on the light, and protect warm/hot bulb glass from cool water. you can get some decent buddage from flowers that typically wouldn't have anything but shake before.

  3. #3
    New Member
    Join Date
    Aug 2010

    Re: Putting lights UNDER the plants to help bottom growth?

    my logic is that if you can see light through the leaves, it's reaching the active cells that need it, regardless of which direction it's coming from. my only concern would be the heat generated from underneath the plants might affect stomata function/transpiration rates. but with CF/low-heat bulbs, i don't see that as a problem. go with your intuition man. i think you're on to something.

  4. #4
    420 Member OldSkoool's Avatar
    Join Date
    May 2006
    Middle Earth

    Re: Putting lights UNDER the plants to help bottom growth?

    May I suggest that you avoid the expense and trouble of additional lighting by simply using LST methods to provide direct light to stimulate lower bud development. What would normally be small popcorn buds develop into 3" to 4" nugs, at least that's been my experience.

    I would not recommend cutting lower branches, IMHO, this would not only reduce your yield, but possibly cause plant shock.

    Good Luck!

    Free your mind, and your ass will follow