When a hydrangea does not form buds it is rarely due to fertilizing. Most likely a blast of cold weather in early spring that hit only the most exposed plants or sections that were most in the open will kill flower buds or the most common reason is pruning earlier that removed the two year old wood that creates the flowers. Did you harvest the hydrangea blooms on this shrub last year? If so you could have cut off the two year old growth. This does not apply to the newer Endless Summer hydrangeas or the winter hardy Mountain hydrangeas that flower despite cold spells on both old and new wood. You may be surprised this summer when some of those branches form flower buds just a bit later than the others. Do not prune this year and I am going to bet you will have a huge hydrangea harvest next summer. Keep growing, Marianne Binetti