Lumens for Giant Pumpkin Seed Starting

Let me say up front, I'm not an expert on lumens and growing under lights, but I have done it for 8 years now so I'm not a novice.  When I start my pumpkin seeds I start them indoors under lights.  My setup includes putting the plants on the top of one of those standard plastic shelves that you can by almost anywhere that has a grated shelf.  On the bottom shelf I have a thermostatically controlled space heater and everything is in a closet.

In my new house I have a dedicated grow closet that is used for starting plants and the rest of the year I store my growing products in it.   At my old house I had florescent and T5 lights above the plants with full spectrum 6000K CFL bulbs on the side that are in brooders pointed at the plant.  This setup has always worked well.  The plants have always been short, stocky and not leggy which can happen when the plants don't get enough light.   The color always looked good too.

At the new house my florescent fixtures are too large to fit the grow closet so I just bought some additional T5 fixtures.  I like the T5 fixtures because they don't get too hot and they are nice and bright. With the T5s I'll continue to use the cfl bulbs with the brooders.

Now, for how much light do you need on your plant?  A T5 bulb 3-5 inches above the seedling with a CFL bulb in a brooder pointed at the plant from the side seems to be enough light.  I like to put the plants in the sun anytime I can, because you can't duplicate the sun and you need to get the plants used to the sun's brightness.  Also, a light wind is a good thing to help get the plant to harden off a little.  I think it also encourages root growth some.

A minimum of lighting needed for your pumpkin plant is around 2,000 lumens per square foot.   That would equal about two 23 watt CFL bulbs on a seedling. Mid-range would be around 5,000 lumens per square foot.  That would equal three 23 watt CFL’s.  What would be considered optimal for most indoor grows would be around 7,000-7,500 or higher, but for young seedlings I'm not sure that would be ideal or necessary.  That would equal five 23 watt CFLs.

For my T5 setup with the CFL bulb, I'm getting about 4,600 lumens, but there are multiple plants, so I have multiple bulbs in the area of each plant.  I would guess that each plant is getting right around 5,000 lumens per plant or a little more and it seems to be adequate to get the plants started until you can get them into the hoop house to get them fully going.