Strawberries

I have strabs planted in 2 small narrow window boxes that were given to me. They are sending out long stalks and I think they want to spread. How can I get them to do that , given that there's no room in their box ? can I snip the long feelers and re plant somewhere else ?

 

Can you put a smaller planter beside this one, and root the feelers in that? When they have rooted, then you separate from the mother plant (I think?). You can then transplant them into their permanent spot? I don't know if there is a right time to do this or not but would think that putting energy into fruit and into rooting at the same time might not be a good idea. Posssibly wait till after they have fruited for the year?

 

OK - like baby spider plants ?