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Grow racks at night

Grow racks at night

Plant racks, light stands…I usually call ’em grow racks. They’re filling up now.

Pushed to capacity, the three racks can hold a total of 36 trays, 12 each, or four trays per shelf. So, depending on the size of the plug sheet—I use 38s, 72s, 128s, 200s—I can start between 1,368 and 7,200 seedlings.

Sounds super-efficient. HOWEVER, it comes down to the light. With four trays per double fluorescent fixture, the light is pretty stretched, and a lot of rotating is in order.

Also, most of the fixtures are the old standard T-12 type, where the light is stronger towards the middle of the tube. You can clearly see the difference in growth if you leave trays in the same position for a few days. The newer T-8 type lights more evenly from end to end and uses less power, but I don’t feel like replacing all the fixtures (a couple in there are already T-8).

It’s an ongoing experiment to see which size plug sheet to best start in for each crop, given the light situation. That in turn determines if or how often I need to pot up to larger quarters before it’s time to transplant into the field.

All in all, I’ll get around 2,500 seedlings off the racks this year.



  1. And now the T-5!!  I am seeing a  rack of 8 T-5 lights bloom tomatoes in the window of the grow store, so actually, they are getting sunlight as well as fluorescent light.  Man, these tomatoes are huge and the leaves are thickly green!  To be able to bloom with a fluorescent is a huge breakthrough in energy consumption, cost, and waste.
    I like your blog.  Thanks.

  2. Problem with T5 is that the fixtures are mighty expensive, and hard to find.  Otherwise, yes, they seems ideal for grow light and such.
    I am vaguely considering LED, mostly because they take up much less space, by my are they expensive…

  3. I am trying to determine if T-5 or LED arrays are strong enough to bloom large fruiting plants like tomatoes, peppers, etc.etc. on their own/ without sunlight.
    There are supply stores that offer t-5 parts individually that can be put together at home for much less than buying pre made racks.  Sorry, I don’t have a link to the store on hand though.

  4. plant rack

    […] Grow racks at night | Mar 17, 2007 … Plant racks, light stands…I usually call 'em grow racks. They're filling up now. … […]

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