Junipers flower and produce pollen in spring (May here) and can aggravate allergies and asthma.  The rest of the year they should not be a problem.  They are not “water hogs” but should be watered during dry spells for the first few years as the get established.  Moonglow junipers prefer full sun so they should be far enough from other, taller plants to insure that they get 7 or more hours of direct sun per day during summer.