Hydroponics in cold weather?

pjcampoDecember 28, 2011

I was wondering if anyone could provide some insight on growing hydroponically in an unheated garage in NJ.

The garage is attached to my home on 2 sides and the basement is somewhat heated so there is some warmth lost to the garage.

With addition of a 1000 watt MH lamp, I am sure that it will not get below freezing, however I wouldn't count on anything much above the high 30s. I could also heat the space with a cheap unvented natural gas heater but this brings up moisture concerns among other things.

For lighting, I do not plan on skimping. I was thinking a 1000 watt MH lamp covering a relatively small area of about 16 sq ft (Is this overkill? It's about 62 watts per square foot) on a AeroFlo 36 Aeroponic System (or something similar?).



Can I grow anything such as claytonia, kale, arugula, spinach, or a hardy lettuce WELL under these conditions (fair amount of light, not a lot of heat). If so, what sort of yield could be expected assuming proper nutrients.

I do not plan on re-selling, but consuming and giving away the rest to friends/family. I know lighting bill on 1000 watts * 16 hours a day will cost me $90 a month so this has to be considered.

Any recommendations on different lights or systems?

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Have you considered one of those mylar tents? I would think that'd keep the lamp heat 'in' and get pleasant temps while its on. You could also possibly insulte the outside of said tent with some rigid insulation.

    Bookmark   December 28, 2011 at 9:48PM
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Well a couple of ideas, first I don't use artificial lighting, but 1000 watts for 16 square feet (4 feet by 4 feet) is overkill for sure. 400 watts should be just fine, and for low light requirement plants like lettuce, greens, and non fruiting plants, 2-200 watt HPS lights should be able to give you very good coverage for more than twice that square footage.

Grizzman's suggestion is defiantly something to consider if you have the money. However for the price of one of those tents ($300-$1000+) I could build a much larger insulated room using 2x3 or 2x4 wood framing, and OSB paneling for the walls. Then simple white reflective paint for the inside, and using 1/2 or 1/3 inch Styrofoam insulation panels on the outside. You could probably build something like a 20x20 room for about $400 to $500. The largest grow tents I have seen are only about 8x8, and run over $1000.

I'm personally a fan of building my own systems (etc.). So even though the system you mentioned should work fine for some plants (not large plants that would need support). I would much rather build my own systems because I get much more value for my money that way, and I can customize it to my needs. Again here I would just prefer to build my own systems. The commercially built systems are just way overpriced in my opinion (any of them). But on the other side of the coin, not everyone is comfortable building their own.

Most cheep gas heaters aren't rated to be used unattended. Though some are fitted with safety shutoffs, and without any way to control heat buildup in the room from both the lights and your heat source you will need to closely monitor the temperatures. Though you would still want to vent the room because you don't want to deplete the oxygen levels, or wind up with high CO2 levels either.

However again if you good with your hands, it wouldn't be hard to create a temperature controlled ventilation system using simple inline duct fans (or any electric fan/s), and a inexpensive household heating/AC thermostat. Also some portable gas heaters come with a thermostat control.

One way to monitor temperature and humidity in one room from another is by using a weather station with a wireless remote sensor. You can find them for under $40. I bought mine at Wal-mart or K-mart for $39. But some more basic models still come with a wireless remote, and I have seen them for as low as $20. My remote censer works up to 100 feet away from the base station (witch is in my bedroom).

    Bookmark   December 29, 2011 at 5:40AM
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Thanks...I really wouldn't want to use a gas heater unless I had to. I would think that the nutrient temp is more important than ambient for these types of plants and that could be controlled a lot more easily and cost effectively I think.

I am getting suggestions to use HPS but have always read MH is better for vegetative growth. I know that the folks at Cornell CEA are using HPS though so I am a bit confused there.

    Bookmark   December 29, 2011 at 8:37AM
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Sorry I said HPS, but meant to say HID witch includes both MH and HPS. But for non flowering plants I would go with strictly MH as well.

Air temp is just as important to the plants also. Just like low water temps, low air temps will stunt your plants growth too. The amount of photosynthesis the plants leaves can do is related to the air temp also, not just the amount of light they receive. So if it's to cold, they wont be able to do the photosynthesis to grow very fast regardless of how many watts of light you provide. At least until the point where the lights provide enough heat to act as the heater, and thus raise the air temp to within a good range for the particular plants you are growing. Then photosynthesis will increase, thus plant growth will increase also.

    Bookmark   December 29, 2011 at 3:13PM
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My unheated grow room (garage attached to house) probably gets below as 35 deg.f during some cold winter nights. Colder air temps do seem to slow growth rates slightly, but not much. However my DWC reservoirs are almost always around 75 deg. f or higher due to the use of utrasonic foggers. I would say root zone temps are much more detrimental than air temps at least up to a certain point. I know I wouldn't be able to grow much of anything in soil at these low temps. Aquarium heaters should work well also. Keep the reservoirs off the floor.
Heating an area that needs to be ventilated (to provide CO2) using HID, just doesn't seem to make all that much sense to me. In effect you would be blowing huge amounts of electricity out the window using an electric fan to do so.
Good Luck,

    Bookmark   January 2, 2012 at 8:58PM
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Both air and water temps are important, I don't think either is more important. Though plants have evolved over billions of years where the roots are growing in soil where they are insulated from the above ground temps. It can be below freezing above ground, but a few feet down (depending on soil type and wetness) can still easily be in the 60's. But they still need warmer air temps (then the 30's and 40's) to do well.

My mom still wonders why her tomato plants haven't grown more than a inch or two in almost two months. And they wont either until mid February when the air temp begins to rise daily into the 80's. At the same time the ground temps wont change more than one or two degrees (if that). But the tomato plants will explode with growth when the temperature get into the 80's (if she can keep them alive until then).

But if you don't want to worry about low air temps, that's fine. Though I would advise you still keep it in mind for when your plants aren't growing fast enough. Then raise the air temps and see for yourself how much difference it makes. Lettuce is a cool weather plant, as well as broccoli too, and thus they both will do better in cool air temps. But not all plants are cool weather plants, so what your growing makes a big difference in how they handle cold temps.

    Bookmark   January 3, 2012 at 4:49AM
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I wonder if DWC would make more sense than NFT in cold weather. Maybe the plant would be happier with roots submerged in warm water.

Ken, what do you do for lighting and ventilation?

    Bookmark   January 7, 2012 at 1:27PM
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Can anyone recommend a DWC or bubble system (not DIY) that will hold a decent number of greens. Is the General Hydroponics Rainforest 318 any good?


    Bookmark   January 10, 2012 at 10:55AM
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There is another one called the mega farm, but for very similar price, the Mega Farm looks much more amateur than the General Hydroponics system


Just the size of the resevoir - 15 vs 7 gallons.

Another dumb question... Watt per Watt, is MH better than CF bulb? I do not mind buying a good $250 light if that is going to yield the best results.

    Bookmark   January 10, 2012 at 12:56PM
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Is there a particular reason you don't want to build your own?

As for the wattage thing, if you're growing short leafy plants that are all the same approximate height, I believe CFL's are the way to go because you can get them right down on the plants.

    Bookmark   January 12, 2012 at 3:25PM
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I figure by the time I put everything together and start cutting holes, etc. what I could buy for $200 (The above) looks like a fairly professional configuration. I don't quite understand how the oxygen enters this Rainforest system but it looks pretty good. The reservoir is large and I'm sure it's meant to hold up (I've read of issues with storage totes buckling under the pressure of water).

    Bookmark   January 16, 2012 at 2:14PM
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Rubbermaid totes sometimes have a tendency to buckle if they're large and filled to the brim. Sterlite doesn't have nearly as much that issue. If you're only talking a 15 gallon reservoir, buckling won't be much of an issue.

From your original post, I assumed functional was more important the appearance. I promise you can grow 2 to 4 times as many plants for the same money if you just spend a little time designing it. But if appearance is important and money not an object, I suspect the rainforest will work just fine for you.

It appears the rainforest pumps water up from the rez and sprays the net pots. The water is aerated when the water drips back into the rez. Of course in this system, water aeration is not nearly as much an issue. When the water pump stops the water will drain out of the crevices of your medium and fresh air will replace it.

    Bookmark   January 17, 2012 at 10:14AM
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