ABSTRACT The experiment about effect of concentration of Marga- flor fertilizer and age of seedling on yield Inttuce (Lactuca sativa L.) White Boston varity to hydroponic, had been carried out since December, 1991 until March, 1992, at Cacaban, South Magelang, Magelang, Central Java, at alti- tude of 376 metres above sea leve. …