Float makers use everything from pumpkin seeds to whole flowers, meticulously placing them on the giant structures that will make up the elaborate floats.
"Each float is like a color-by-number and all of the surface that's visible has to be covered in natural vegetation as the color that it's painted on the float," said Leslie Foxvog with American Entertainment Services.
However, they hope the intended messages behind the floral displays will last long after the blooms are gone.
At Fiesta Parade Floats in Irwindale, the AIDS Healthcare Foundation uses their floats to urge bold thinking.
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"It is an advocacy that is really both about the problem of homelessness as well as creative alternative solutions to the problem, said the organization's Ged Kenslea.
Others, like Dole Packaged Foods, are simply trying to spread some optimism and cheer on parade day.
Until they're all actually complete, volunteers will be working around the clock to get the floats ready in time.
Watch all of the festive floats make their way down Colorado Boulevard in Pasadena live at 8 a.m. on Jan. 1, live on ABC7.