Ok I could be well wrong here but I think I am not, orchards flower when they think they are going to die, ie you got a lovely orchard that aint flowered in years but the leaves look really healthy, then just chuck it out into the full sun for a week and maybe every 3 days give it some water, I used to have orchards that I cared for on my balconey here, gently spraying their roots everyday and shading them from the harsh sun,never had any of them flower, had a load of crappy ones downstairs in the front garden that used to get the occasional hose down, the leaves looked shite but did they flower