FPJ is used in solutions for seed and soil treatments and plant nutrition. It consists of the young shoots of vigorously growing plants that are allowed to ferment for approximately seven days in brown sugar. The brown sugar draws the juices out of the plant material via osmosis. It also serves as a food source for the microbes carrying out the fermentation process. The weak alcohol produced during fermentation extracts chlorophyll (soluble in ethanol) and other plant components. It is non-toxic and edible.

The most critical requirement when selecting plants for making FPJ is to use the growing tips of plant species that are fast growers. Flowers, flower buds, and immature fruits can also be used. Hard or woody plants will yield little or no plant juice. The plants should be vigorously growing at the time of collection. Plant parts should be harvested while plants are in respiration mode (before sunrise) and not in photosynthetic mode (during daylight) due to these processes' effects on plant chemistry. Avoid collecting plant parts during or after rainfall (ideally, wait two sunny days after the rain stops) and do not rinse collected plant parts to conserve their surface microbial populations (lactic acid-producing bacteria and yeasts), which will carry out the fermentation process. Low levels of these microbes will result in improper fermentation and/or low yields of plant juice.