Kupukupu Fern is a common fern throughout the tropical areas of the world. We have a native species here in Hawaii, hence the Hawaiian name. However, there are other commercial varieties that have been brought into the islands with a lot of interbreeding going on so not all so called Kupukupu is actually a native type. These plants can look very attractive as a single small plant in a pot or in a group in a large pot or as groundcover. The leaves grow up to two feet long in a mature plant. Wherever they are they will expand their territory and can get a bit wild and wooly looking when old. In the landscape I will pull out the old rough looking plants and let the younger ones take over. As they get crowded together the leaves will gets smaller. You also need to keep some sort of physical boundary for them if you do not want then to spread. Plants grown in the shade will be a darker green in color and the fronds droop over more while those that grow in the sun are more upright in growth. They like moist but well drained soils. I tidy up potted Kupukupu with scissors occasionally...... cutting off those old frond stems or errant stolens. Occasional fertilizer will give them a boost.
Kupukupu Ferns propagate in nature from spores or by sending out stolens with little tubers on them which grow into baby plants. I have some baby plants that pop up in the lawn if the lawn is not being mowed often. They have escaped from a small garden that has Kupukupu as a groundcover. I just pull these up, give them a day in water to perk them up, and then plant them in 4" pots. This is a slow way if you want lots of Kupukupu Ferns for a landscaping job. One day a plant nursery worker shared his secret with me and so I will pass it on to you. You just partially plant the little grape size tubers in potting mix and soon you will have lots of little baby ferns to pot up into 4" pots. Now you can grub around in the garden for a few of these tubers but the best way is to keep a big old root bound potted Kupukupu tucked away in the back yard to provide the offspring. When you pull the root ball out of the pot you will find dozens of these tubers that you just pull off. You can break open the root ball to find many more. Unfortunately I threw out my old Kupukupu mother plant and so I need to get a new one going so I can show you a picture of the tubers on the root ball. It will take a few years before it is really ready to do that. However, you can see some of the tubers that look like mini potatoes in the second photo above. Each of those will grow a plant. Something the little kids might enjoy being part of.