Hi and welcome to GardenWeb!

Well, I don't grow vegetables myself, just flowers. However in regard to growing vegetables in your unheated garage, I'm sure it would depend a great deal on which vegetables you grew. I know that lettuce, for example, will grow in temperatures in the forties. On the other hand, warm season vegetables, such as tomatoes, would probably require temperature at least in the sixties, probably even the seventies?

The heat mats are generally used only for germination. So once the seeds sprout, off goes the heat mats and plastic domes. Continuing to use a heat mat after germination would probably just tend to dry the growing medium out too fast. In any case, you'll need a thermostat to properly control the heat put out by the mat. So, after germination, you're basically depending on the air temperature of the garage. And, usually the moist growing medium will be cooler than the surrounding air temperature.

Your success would also depend on how many vegetables you intend to grow. For one thing, your fluorescent lights need to be kept very close to the plants, usually no more than a couple of inches. You won't be able to get a lot of seedlings under two 48" lights. Of course, you may be planning on adding more lights (you didn't mention).

If you do decide to try using the garage, maybe you could surround the growing area with those silver mylar emergency blankets, they're very inexpensive and should help a lot.

Whatever you decide to do, I wish you the best!

Art

It should work out pretty well as long as you can keep warmth around your seedlings/growing area.

Heat activates seeds and makes sprouts and young seedlings grow faster. Your heat mats will help a great deal in this matter. Also make sure to keep the lights as close as possible to the plants without burning them...that'll provide extra warmth if necessary.

Most people overlook air circulation/ventilation, but it is critical. Nothing invites mold and rot faster than stale air. A regular swiveling fan in minimum setting a few feet away from the plants is fine. The fan also simulates wind, and once youll take the plastic domes off of your starter trays, your stems will pick up some strenght from being pushed around a bit.

I use a 5 tiers resin shelving unit that fits 3 trays per tier. This means I can start 1560 plants at once (you need light over each tier though, but just to show you how much can be done with so little). I got the shelving unit for 25$ at the hardware store here....well worth the investment :)

Go ahead, you'll have a blast! i do this for a living (growing food indoor yes!) and its a thrill everyday! Beware though, this activity is highly addictive as it fills you with a sense of accomplishment and feeds your soul! You may, just like me, go from the corporate world to the farming world :)

Khaled

You might benefit from studying what Eliot Coleman does re winter harvests in unheated or minimally heated hoop houses. Google him and get a book or two from your library, especially The Winter Harvest Handbook. The others are right about how close you need to keep the lights - 2" or so from the growing tips. And yes, the ventilation is very important. For your setup, only a tiny fan is needed... until your addicted, move your car outside and take over the entire garage :-) to get optimal growth you might want to take Khaled's advice and get one of those resin shelving units. They would look real nice in your heated house, and the growth rate really increases.

Here is a link that might be useful: Lively Dirt - the Garden Blog

Kahled, I would be interested in knowing more of what you are doing in your indoor farm. Any website. Or you can contact me through my website. See the link below.

Here is a link that might be useful: Lively Dirt - The Garden Blog