Watch the video on how to collect bottle brush seeds. Most schools and parks across Sydney have at least one bottle brush plant in the grounds. If you are supervised by an adult, go outside and collect some seed capsules off a bottle brush and place them in your seed packet. Write the date you collected them. Leave the seeds for at least 1 week in a warm spot like a window sill that receives sunlight. The tiny 'dust' in the bottom of the packets after 1 week are the bottle brush seeds.