Yes you can. Depending on the stage of seeding.
If the seeds are dark then yes, they are likely to open. Seed pods can still open weeks from cutting the stalk from the grasstree. Some seeds that are closed can also be taken from stalks and put into a glass container and left in the sun.
We have found that many of our grasstree stalks' have about 90% of their seed pods open up to provide seeds with about 10% closed. We experimented and took the closed seed pods, put them in a glass container, and left them in a sun room with some of the other stalks that we wanted to 'seed'. They were all exposed to the morning sun.
Surprisingly we found that the seed pods 'popped' whether still attached to the stalk or seperate in a glass container.
