cattleya growing but not blooming

[newone]

When using bloom boost fert, is it still somewhat effective when the flower buds are already growing in the sheaths or on the spikes?

[silken]

No. Some say it is detrimental. It is better to use a balanced fert or none at all when the blooms are forming. I have also read using some potassium (Last number) can help produce larger better blooms.