Summary Young trees of Cox’s Orange Pippin on M.VII were grown in sand for three-years and given two seasons of treatments. Residual effects were studied in soil in the fourth year. The trees made little new growth in the third and. fourth years. Control trees received a continuous supply of complete nutrient solution containingi meq. NO3/1. (low-N). Other treatments received the’ same solution but the nitrate level was increased to 16 meq./l. in January-February and March (spring-N) or in May, June and July (summer-N) or in September, October and November (autumn-N). The fifth treatment, was a continuous supply of 4 meq. NO3/1. (moderate-N). Summer-N gave greatest uptake and leaf and shoot growth, and. increased the proportion of the total nitrogen going into them. Moderate-N was nearly as effective in these respects, though nitrogen uptake was not so high. Autumn-N did not increase growth, but concentrations tended, to be higher than in the controls and spring-N trees because of a somewhat, greater nitrogen uptake. All additions of N increased the number of axillary blossom clusters per 100 cm. of shoot. The total number of axillary clusters on trees with autumn-N was the same as with spring-N, but autumn-N produced strong, fertile-blossom comparable in percentage set to that with summer-N and moderate-N trees, while spring-N blossom was weak and no more fertile than the low-N. flowers (controls). Blossoming and leaf development were a few days earlier with autumn-N or moderate-N. Summer-N had this effect in one year.