E-mail -- Looking to Increase Yields.

Dr. Myers
Currently I grow bell peppers and tomatoes indoors in a scrog* type system growing hydroponically. I use 4 foot cool fluorescent shop lights which are actually producing quite a bit of veggies. However since my little 5 year old can eat more than I can produce under my current lighting I'm considering an upgrade to a 400 watt hps or MH light. What type of light is best for growing vegetables? If I get a HID light should I continue the scrog grow or grow more plants and let them grow tall? I have about a 20 by 10 foot room so how hot will a HID light heat the grow room?  Also, what do you recommend for venting out through a window?

Thanks, keep up the great work on the blog.

You have the right idea, you will need to increase the light output to increase growth/yield. Also, think about growing outdoors in the summer and canning etc. to get you thru the winter months. You can't beat the sun as a light source. (and it is free)
I really like HPS lights, and they will help promote fruit/veggie/flowers. However, I am starting to like some LED’s (BEST LED and 2nd test link) The next generation of LED's that use 2 and 3 watt bulbs, they are really working great, they are beating the High Output T-5 Fluorescents which uses twice the watts!
I have not compared a scrog method to the traditional method but I know with a higher wattage HID you won’t need to use scrog. The scrog method I think is better for lower light output as it spreads out the growth under all available light. However this method is always good if you have limited vertical height.  I would guess if you let plants grow taller and bigger in general, they should produce more... you want to make sure the bottoms of the plants are getting light, if you have a foot or more of bare stem at the bottom of the plant you need to increase light or keep the plants shorter. If you do go with an HPS, you should put a fan in the room to blow over the plants, the high red/yellow of the HPS promotes fruit/flowering but also can make plants stretch as they grow. A light breeze blowing over the plants will help keep plants shorter. The fan also helps control heat. If you are going to vent out a window, make sure there is a good screen, insect pests will thrive in your grow space. You will have to deal with heat a lot more with HID lights than your current set up but your room seems large enough for a 400 or 600 watt HPS. A 400 HPS is good for a 4’x4’ area and a 600 5’x5’ in general. The room may be in the 80's or 90 but should not get hotter than that unless you live in an area that has higher outside temperatures. Tomato's and peppers are tropical so while you might find 80 too hot, they will be fine. If your room gets in the high 90’s or for sure over 100 you need to vent the heat out or you will have slowed plant growth. I started growing with T-12 bulbs and I can tell you if you are doing well you will have exponential improvement even with a 250 Watt let alone a 400 watt in both yield and rate of growth. If you do go with the HPS, keep the cool white bulbs and start your plants under them for the first couple weeks of growth, as HPS can make plants especially seedlings get long and grow too tall. Tomato's need staked as it is and they will grow taller with an HPS.
Good Growing
Dr. E.R. Myers

* SCROG is The Screen of Green method of growing indoors. Basically you have a screen placed horizontally 1.5-2 feet above the plant medium and train the plants to grow in a more horizontal way by tying branches to the horizontal screen (chicken wire or other fence types are often used as the screen). This is good for growers who have limited vertical space and for growers who use lights like fluorescents that have lower light outputs since it maximizes the grow space used.

Read my latest post comparing SCROG to a traditional grow method

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