A method for controlling polymer morphology in olefin polymerization, comprising: flowing a catalyst through a first concentric flow path of an injection nozzle having two or more concentric flow paths and into a fluidized bed disposed within a reactor; flowing a feed comprising one or more monomers, one or more inert fluids, or a combination thereof through a second concentric flow path of the injection nozzle and into the fluidized bed determining the weight % of fines, contacting one or more olefins with the catalyst within the fluidized bed at conditions sufficient to produce a polyolefin, and controlling one or more of: i) the temperature of the second concentric flow path or ii) the flow rate of the feed through the second concentric flow path; wherein an increase from a first temperature to a second temperature and/or increase in the flow rate of the feed from a first flow rate to a second flow rate increases the percent of polymer product fines by at least 1% based on the weight % of fines produced at the first temperature or the first flow rate; or wherein a decrease from a first temperature to a second temperature and/or a decrease in a first flow rate to a second flow rate reduces the percentage of polymer product fines by 2% to 75% based on the weight of fines produced at the first temperature or the first flow rate. flowing a catalyst through a first concentric flow path of an injection nozzle having two or more concentric flow paths and into a fluidized bed disposed within a reactor; flowing a feed comprising one or more monomers, one or more inert fluids, or a combination thereof through a second concentric flow path of the injection nozzle and into the fluidized bed determining the weight % of fines, contacting one or more olefins with the catalyst within the fluidized bed at conditions sufficient to produce a polyolefin, and controlling one or more of: i) the temperature of the second concentric flow path or ii) the flow rate of the feed through the second concentric flow path; wherein an increase from a first temperature to a second temperature and/or increase in the flow rate of the feed from a first flow rate to a second flow rate increases the percent of polymer product fines by at least 1% based on the weight % of fines produced at the first temperature or the first flow rate; or wherein a decrease from a first temperature to a second temperature and/or a decrease in a first flow rate to a second flow rate reduces the percentage of polymer product fines by 2% to 75% based on the weight of fines produced at the first temperature or the first flow rate. i) the temperature of the second concentric flow path or ii) the flow rate of the feed through the second concentric flow path; wherein an increase from a first temperature to a second temperature and/or increase in the flow rate of the feed from a first flow rate to a second flow rate increases the percent of polymer product fines by at least 1% based on the weight % of fines produced at the first temperature or the first flow rate; or wherein a decrease from a first temperature to a second temperature and/or a decrease in a first flow rate to a second flow rate reduces the percentage of polymer product fines by 2% to 75% based on the weight of fines produced at the first temperature or the first flow rate. wherein an increase from a first temperature to a second temperature and/or increase in the flow rate of the feed from a first flow rate to a second flow rate increases the percent of polymer product fines by at least 1% based on the weight % of fines produced at the first temperature or the first flow rate; or wherein a decrease from a first temperature to a second temperature and/or a decrease in a first flow rate to a second flow rate reduces the percentage of polymer product fines by 2% to 75% based on the weight of fines produced at the first temperature or the first flow rate.