By Janet Bayers Updated January 04, 2022
Nursery flats – the black, plastic trays that hold plants in separate pots – come in several standard sizes. Each holds different number of plants. When buying plants in flats, ask for the specific capacity of the flat so you know you're getting enough plants.
Standard Flats
The most common flats are long, narrow rectangles that hold 18 square 3 1/2-inch or 4-inch pots. Called Daisy Trays, they have wide bottom grids for good drainage, says Greenhouse Megastore. They hold six six-packs of 2-inch starter plants or 12 six-packs of 1-inch starter plants.
Anderson Flats
Heavy-duty, wider, rectangular Anderson flats have 3/4-inch lips on both narrow ends and a small-grid bottom, says Anderson Pots. They come in several sizes, but the most common, the Portland flat, holds 25 4-inch pots.
Square and Molded Flats
The most common square flat has a bottom with widely spaced grid lines and holds 16 4-inch pots or 25 3 1/2-inch pots. Some flats have molded cups to hold round or square pots. While capacities vary, the molded flats commonly hold fewer plants because the molded bands create spaces between pots.
