judgment | synonyms: alternative, choice, decision, desire, determination, discretion, election, option, pick, preference, selection, volition, wish, acumen, astuteness, cogency, comprehension, erudition, genius, intellect, intelligence, knowledge, mastery, perspicuity, profundity, sagaciousness, sophistication, wisdom, adjudication, appraisal, arbitration, assessment, consideration, finding, justice, mediation, pronouncement, resolution, ruling, sentence, verdict, abatement, burden ...
Cut the dead or diseased stalk back to the base of the plant. Cut damaged stalks below the damaged part to leave the foliage to feed the plant. Prune the stalks back to the base of the plant in late fall when the lilies have stopped blooming and the foliage is dying off. Pruning shears.
After flowering, you can deadhead the lilies, e.g. cut the spent flowers off, but do not cut back the stems. The stems will green leaves will produce the energy required for next year's bloom. If you cut back the stems, you will cut off energy for next year's bloom and worst case kill them. You can not affect the height of the lilies by cutting them back. Their height is genetically determined. If the height bothers you, dig the lilies and trade them for dwarf (low growing) lilies. If you cut lilies for arrangements, try to cut maximum 1/3 of the length of the stem leaving 2/3 minimum to recharge the bulb.