Pollen viability refers to the ability of pollen to germinate and grow once it lands on the stigma. The period of viability for pollen is highly variable. To an extent, it can be affected by the prevailing temperature and humidity.
In some members of Rosaceae, Leguminoseae and Solanaceae, pollen remains viable for months.
(1) In some members of Solanaceae, pollen viability can be maintained for months. In Liliaceae members, pollen viability ranges between a few days to a couple of weeks. Some Poaceae members loose viability within 30 minutes.
(2) In Brassicaceae plants, pollen viability ranges from several days to weeks. 
(3) In members of Rosaceae, pollen viability is for a few months while some Poaceae members loose viability within 30 minutes.