How many seed trays fit on a wire shelf?
A 48 x 24 inch shelf holds four 1020 flats. The count changes with the real outside size of your tray, so measure it.
Common shelf sizes
| Shelf (length x depth) | 1020 flats that fit |
|---|---|
| 48 x 14 in | 2 |
| 48 x 18 in | 2 |
| 48 x 24 in | 4 |
| 36 x 18 in | 1 |
| 60 x 24 in | 5 |
Assumes a 21 x 11 inch outside size, tried both ways round. Trays vary by maker, so enter your own size in the calculator.
How to count
- Measure the outside of your tray, including the rim. A "1020" flat is about 10 x 20 inches inside the base, but the outside is larger.
- Divide the shelf length by the tray length, and the shelf depth by the tray width. Round each down to a whole number and multiply.
- Try the tray turned 90 degrees and use the larger count.
- Leave a little room at the edges. Wire shelf posts take some space at the corners.
Lights and trays together
The lights need to cover the trays. A tray that sits outside the width of the light row gets less light, and Oklahoma State notes that the ends of a fluorescent tube lose about 3 inches of intensity, so keep trays inside the bright part of the fixture.