So it says 10-10-10, the question often asked is; what do the numbers mean? The important question is; what do the numbers do?
To answer the first; nitrogen, phosphate, potash.
To answer the second: nitrogen means an abundance of green leaves; phosphate means blossoms, fruits and roots -- with a touch of disease prevention and; potash means stems (trunk and branches) and disease prevention.
I'm old enough to remember being told not to fertilize after the flower
buds appeared. (We didn't have specialty fertilizers readily available way back in the stone age.)
If you use commercial fertilizer, start with balanced and switch to bloom. Soak a little balanced into the soil before you plant
or transplant, add a bit more once they start to thrive and then move to a low first -- high second number formula when the blooms appear.
If you use commercial fertilizer and follow this advice, you may be able to ride out weather extremes and never experience blossom end rot.