Garden center prices for vegetable starts are expected to be at an all time high this year, due to increased demand from gardeners and higher fuel costs for growers. That is why it makes sense to start your own at home. You can buy seed starting supplies anywhere seeds are sold, or use almost any type of container to hold them until they are ready for the garden. For most people, however, the biggest obstacle to starting seeds early is the availability of a sufficiently well-lighted growing space. Fluorescent lighting provides the best option for indoor growing for home gardeners.
We already have flats of seeds growing under lights in the garage. A second round of lettuce will be ready to move into the cold frame in a week or so. Broccoli, leeks and even some experimental tomato plants are thriving. The garage has two south-facing windows, each about 36 inches wide. In front of each of these we have set up a baker's rack measuring approximately four feet wide by 18 inches deep. Four foot fluorescent shop lights, each holding two 40-watt fluorescent lamps, hang from the shelves on chains. We have found that three shop lights (a total of six lamps) per shelf provides sufficient light for all types of vegetables. If one were only going to grow greens, you could probably get by with only two units (four lamps) per shelf.
I bought "cool white" lamps, because they are the least expensive, a little less than a dollar apiece when purchased in a case of ten. At 3100K they are not exactly the ideal color temperature for plant production. Daylight lamps, at about 5000-6000K would provide more energy in the areas of the color spectrum that plants absorb. However, we have achieved satisfactory results with the cool whites, and the daylight lamps are considerably more costly.
Standard seed flats are 10 inches wide by 20 inches long. Four will fit across each shelf, for a total of 16 flats per rack. If we use 36-cell trays for starting seeds, which we do for lettuce, we can accommodate a total of 576 plants per rack or 1152 plants between both racks.
The shop lights are relative cheap, about $10 each. We have 12 per rack, so the total cost is about $240 for the light fixtures. The racks themselves we have had a long time. You can purchase similar ones for about $50 each. Add another $25 for timers and extension cords, and the total cost of the set-up is about $375. Allowing $1.00 each for lamps, we have $48 invested in that component. The lamps will last two seasons before they dim enough to need replacement, but the other components will last through many growing seasons. Given that a small greenhouse costs close to $1000, our garage system seems like a bargain-priced way to start a modest number of vegetable plants. If it lasts us for only 5 years, the equipment amortized cost is $6.55 per month, plus another $2.40 per month for lamps. The amortized cost for a $1000 greenhouse is twice that.
How much is it costing us to operate our indoor garden? Our garage is well-insulated, and we heat it to about 60 degrees with an oil-filled radiator heater. Since we use it for many types of projects, we don't count the cost of heating in our calculations for plant production. The cost of lighting is easy to calculate. We have 48 lamps at 40 watts each. That is 1920 watts. If we operate them for 12 hours per day, we use just a shade over 23 kilowatt-hours of electricity. At our present rate, a kilowatt-hour costs nine cents, so the light system is consuming $2.07 per day, or $62.10 per month, in electricity. At most, we will use it for three months, for a total of $186.30 in operating expenses. This is far less than the value of the vegetables we will produce from the plants we are growing now. A small greenhouse, by contrast, would cost more just to heat, depending upon the heat source, and might actually need supplemental lighting during the shortest winter days.
Any way you look at it, the indoor garden seems like a more affordable option than a small greenhouse.
Obviously, not everyone will need to start more than 1000 vegetable plants, and not everyone will want to invest this much in equipment. Nevertheless, it is easy to see that you can devise an indoor light garden with simple, out-of-the-box equipment. If all you want is two or three tomato plants and some lettuce, you can start enough plants underneath a single shoplight, and the cost will be less than $25 for the whole season.