Thick rinds on Washington Navel tree

Have a 4 year old tree that is doing well. Green leaves, lots of new growth and tons of flower buds. It produces well - I allowed about 15 oranges this year. They’re on the smaller side still, but are sweet and very good eating.

Issue is with thick rind. Problem was worse last year - added bone meal to the soil as I read that lack of potassium could be an issue. I fertilize twice a year with Gro Power 5-3-1 N-P-K. Overall tree seems very healthy, just would like to see a more normal fruit. Any ideas? Thanks!


Too much Nitrogen in proportion to P and K. For excellent citrus fruit you’d like annual proportions of 3:1:2 by weight – not volume. Fertilizers with N-P-K of 3-1-2, 6-2-4, 9-3-6, etc. meet this criteria.

The growpower 5-3-1 – which I have used, is not an ideal balance but still a reasonable offering. One pound of it contains 0.05 lbs N, etc.

As for quantity in citrus growing regions of California, a tree your size could utilize up to net 1/2 lb of N per year.

Thank you. This information is really helpful.