Protea plants can be grown from cuttings. It is unclear whether or not your bouquet flowers can be started, as it is hard to know what the florist did to them before you received them However, it is worth a try. Protea cuttings can be rooted from root cuttings. The procedure for rooting cuttings from a live plant follow and you can try to do the same with your bouquet flowers.
Cut branches just below a flower or forming bud, using clean pruning shears. Place the cuttings inside a large, sealable plastic bag that has been sprayed inside with water. Seal the bag. Keep the cuttings in this bag until you are ready to plant them - up to three hours.
Prepare a growing medium by mixing together two parts couarse sand and one part peat moss and place in a flat or in pots.
Remove the cuttings from the plastic collection bag and cut off the leaves from the bottom two-thirds of the cutting's stem. Dip the bottom of the cutting in growth hormone (which you can purchase at a plant nursery) and shake off any excess.
Push treated cutting into prepared pots or flats, leaving only the top third of the cutting above the potting mixture and water the cuttings with a mister. Keep the cuttings moist and warm, misting as necessary.
You'll be able to tell the cuttings have taken root when you give them a gentle tug and they resist.
Repot rooted cuttings in a bigger pot and in the spring, begin taking them outdoors a little at a time each day until they can spend the entire day outside. Then plant the young protea in full sun in well-draining soil.
Protea prefer poor soil, so it is not necessary to fertilize them It is helpful to mulch them with an organic material such as leaves or wood chips to retain soil moisture. Do not overwater.