Impossible to tell without a picture....but have a look at Salvia meyeri (aka rhinosina), and Salvia macrophylla (aka 'Peru Blue'). These tend to drop seeds. Also check Salvia amarissima and Salvia urica and Salvia rypara. There are photos on my site www.robinssalvias.com .

What is the size and density of the flowers on the spike? S. rypara rarely gets above 3 feet tall, as far as I know. S. macrophylla has a distinct shape. S. urica is a medium to dark blue, S. amarissima is lighter and on the lavender side.

I don't remember the size of the bloom although its not large.It will be another month before it blooms.I remember it being more light to medium blue.Its around 5 ft tall right now and some of it leans over somewhat though the stem seems strong enough to hold it upright.

I'm predisposed to calling it S. urica or S. amarissima.