Fluorescent Lighting, and
Flood and Drain Timing
I have a hydroponic system for my garden and I'm using fluorescent lighting. I know it's not the best, but it's best for my light bill and I've heard its fine in the beginning stages (HPS lights are best in flowering stages). How can I simulate Autumn sunlight without having to purchase high pressure sodium fixtures or metal halide?
Also, how often should I flood and drain the nutrient solution in a day with an ebb and flow system? Thanks.
Answer: Fluorescent lights are fine to use on seedlings, clones, and in the vegetative stage....as long as you keep them close and as long as your plants are shorter than 15 inches tall. Past that, the light is not intense enough to support healthy growth. If you try to use regular fluorescent lights to flower your plants, you are likely to be very disappointed with how much produce you get for all your efforts. With that said....
Whenever using fluorescent lights, always buy the bulbs with the largest number of lumens on the box (this is a measure of usable light to the plants). Fluorescent lights called "cool white" or "cool" will have more blue, and therefor would be better for the veg stage. Lights marketed as "warm" contain more red spectrum light, which is more beneficial to flowering (like Autumn light). In reality, this makes little difference when using fluorescents because the light is not intense enough in the first place.
The most affordable lighting solutions with a little more "kick" (for flowering) would be- One, a compact fluorescent light. Two, T5 fluorescent lights (also known as Tek lights). Three, a small HPS light. Once you are dealing with this stronger group of lights, having more red light in the spectrum may actually provide the benefit it is supposed to.
If you only have a small garden, you can get away with a smaller HPS light. Do a search on the internet for "HPS security light"....you may be surprised how affordable some of them are. I found one 150 watt model for $39.00! If you only use it for flowering (12 hours on per day) the cost in electric shouldn't be that bad at all (less than $10 a month I would guess). You can also find these type of security lights at Lowes, Home Depot, and maybe even Wal-Mart.
T5 light fixtures can be a little expensive (but you only need to buy the light fixture once). They are pretty easy on the electric bill, and produce results comparable to a small HPS.
If you buy a compact fluorescent (the kind with very high lumens and a light reflector hood), you will spend more than you would for the HPS light, but slighly less than you would for a 4 bulb T5 light. Compact fluorescent lights (the kind made just for indoor gardening) are easy on the electric bill, and pretty comparable to the other two lights as far as the results go.
Try to find out how many lumens each light produces before you buy one. This is how much usable light it is going to produce. When you go to set up the garden, however, you want to use the number of watts to figure out how big of a garden space you can have. Flowering plants that love light should be given about 40 watts per square foot of the garden as a minimum. If you want results, try to make it your goal to hit this number. Read over my grow light selector page. It contains some math that will help you figure out the proper garden size for whichever light you end up choosing.
Finally, how you run the flood and drain schedule depends on what kind of grow medium you are using in your hydroponic system. Rockwool absorbs lots of water quickly, than tends to hang onto it. Clay pellets, on the other hand, need to soak for about 20 minutes to absorb the proper amount of moisture, and than they drain fairly quickly.
If using a medium like rockwool (or coconut coir), I suggest flooding the table for just a couple of minutes once a day. If using clay pellets, flood them for about 20 minutes perhaps four times a day. In the end, you will want to keep an eye on the medium and on your plants and fine tune your irrigation schedule if your plants look like they need more frequent or less frequent irrigation (but that should be a good place to start). I hope this helps, and Happy Growing!
