Seed Starting Shelf

Enlarge Image Image Gallery iStockPhoto.com/Zeliha Gurkan

For years, I made unsuccessful attempts to start tomatoes and peppers from seed. Each time the seeds sprouted nicely and appeared to be off to a good start. But, as the safe time to harden off the plants approached, they were usually spindly and weak. When it was time to set them out, I’d make another trip to the garden center to buy tomato and pepper plants.

Persistent as I am, a year or two later, I’d try again, each time thinking that I had found some better way. I had the required sunny south window, so inadequate light didn’t strike me as the problem until I noticed that in March (when I planted the seeds), sunlight bathed my seedlings, but as the sun climbed higher in the sky, the patch of light grew smaller and smaller until the overhang on the south side of the house blocked it entirely.

Based on this observation, I decided I needed a different approach to providing light for the seedlings, so I built a shelf system using inexpensive, fluorescent shop lights. I had the system ready to use in the spring of 2000, and I’ve used it with good results each year since. In planning the system, I included a lower section as a place to over-winter herbs in pots. After a winter under lights, rosemary, basil, sage, thyme and oregano look a bit bedraggled, but after a few weeks outside in the spring, they thrive again.

Material List

• 3 12-foot 2-by-2s
• 2 10-foot 2-by-2s
• 1 8-foot 2-by-2
• 1 12-foot 1-by-2
• 6 10-foot 1-by-2s
• 4 4-by-8-foot sheets 3/16 inch (5.2mm) luan plywood
• 40 3-inch deck screws to fasten together 2-by-2 box frame
• 40 2-inch deck screws to fasten together shelf frames
• 210 No. 6 3/4-inch screws to fasten plywood to framing
• 20 No. 8 3/4-inch pan head screws to fasten lights to framing (if not using chain)
• 20 1-inch cup hooks to fasten lights to framing (if using chain)
• 30 (or 20) pieces shelf brackets; 6 per shelf for 5 shelves (4 per shelf, 5 shelves)
• 6 (or 4) pieces shelf support 6 feet long
• 12 linear feet of 4-foot-wide Mylar (optional)
• 10 4-foot, 2-tube fluorescent lights (see discussion of materials)
• 20 cool white fluorescent tubes (see discussion of materials)
• 1 timer
• 1 10-outlet plug strip or 2 6-outlet strips
• 4 (or 6) medium-duty casters (optional)

Construction notes

Extension service experts indicate that one light is sufficient for two standard 11-by-21-inch flats. However, if you intend to use most of the surface area of the shelves, two lights are required to provide the recommended 25-30 watts per square foot.

Different types of fluorescent tubes can be used. The sources I consulted recommend ordinary cool white tubes or a combination of one cool white and one daylight tube in each shop light fixture. Experts generally agree that the so-called grow lights or plant lights don’t produce appreciably better results and are more costly.