Paul, yes, a pic of your Y.rostrata would be great!
99% of my plants are going back indoors over winter, so I'm not too concerned I'm fertilizing so late this year.
Just didn't get around to it earlier.
Your fertilizer selection is reassuring...that's basically what I've got too.
Last winter, the nursery had a 50% off fertilizer sale...I ended up buying a box of
everything
treble superphosphate 0-45-0, sustane natural organic 3-4-2, potassium suphate 0-0-50, and magnesium 10%, sulphur 13%.
Haven't got a clue what to use, on what, in what mixes/quantities.
So I'll stay with the safer, already-formulated stuff.
Barb