Speed up Growth Cycle via Light Intensity

As you know, photosynthesis drives plant growth. An easy way to speed up a plants growth cycle is to give it a greater light intensity. The cheapest and maybe simplest way to grow is with T-12 bubs from a hardware store, and many growers including my self started out that way, but they don’t compare with a T-5. If you want big plants or plants for fruit or flower, you will need to use an HID like an MH or my favorite, an HPS. While plants don’t use light the same way we ‘see’ light, lumens are still an ok way to look at light output. The more lumens a bulb has the greater the light intensity. The color of light is also important. An HPS has a superior light output vs. an equal wattage MH, but its yellow light output makes some plants grow lanky. I recommend using a fan and/or tying plants down. You can also use a MH conversion bulb with a HPS ballast for vegetative and then switch to the normal HPS bulb for flowering/fruit. In some cases, these conversion MH bulbs put out more lumens than an actual MH!

I think the fasted way to get plants to maturity is to start them under a T-5 (blue bulbs) in small containers and then pot them up and put them under a HPS when they are big enough to flower. I have a conversion bulb which I use for a couple weeks and then switch to a high output HPS bulb. I usually put a fan blowing on the plants very briskly for the first couple weeks when I switch to the HPS to help counter act the internode stretching that sometimes occurs between plant nodes when plants are grown under HPS. Once most plants have begun to really flower you can cut the fan back to low because plants stop stretching when they have prodcued the hormones for flowering which leads to fruit or seeds.


I started several pumpkin seeds from the same hybrid on a wet paper towel in a plastic bag. The seeds that germinated I put into plastic cups and grew them under a T-12 light for two weeks. All were sitting on a root warmer. After three weeks I potted up eight plants, four I put on a window in my office (winter short days) and the others I put on a shelf with a 400 W HPS with a timer -- on 12 off 12 (mimic short days).  Every day was "sunny"for the HPS, but the window had at best several sunny days and only 1 hour maximum of direct sun on those days.  I apologize that the pictures did not turn out that well but at least you can see that the plants under the HPS are bigger and are flowering. The window plants had the same number of hours of light  but are basically stagnant or growing slowly.  Even the HPS plants are not the best looking plants because they are in small containers.  I kept all plants in the same size pots so that everything would be the same accept the light intensity. I should have transplanted the bigger plants under the HPS into 5 gallon buckets if I really wanted to harvest them.

Good Growing,
Dr. E. R. Myers

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