...If your further than 1/2 way through flowering, I wouldn't worrie about it...finish them off. However, If they are still early yet...I'd add some rapid dolomite lime, 1 tbls per gallon of soil as a top dressing, water in as normal. Dolomite lime will keep your soil's pH in check and provide cal./mag. Looks to me you either have a cal/mag def...or a pH issue....dolomite lime should fix ya right up. Peace.