Question: I planted native Hawaiian kupukupu fern around my epic hapuu Hawaiian tree ferns. The kupukupu went nuts, grew really well and is even climbing up the hapuu trunk. The hapuu fronds seem smaller now.
Is this normal? Should I pull out the kupukupu ferns? I really love my hapuu and other native plants in my yard. Also planted around the hapuu are palapalai ferns and maile. I got these great native plants at benefit plant sales at Lyon Arboretum and Bishop Museum Grow Hawaiian Festival. — Mahalo, Ray Shito
Answer: Hawaiian rain forest plants like these like to be crowded, or they like to “cuddle up.” In an intact native Hawaiian forest, every layer will be filled with plants of varying heights and sizes from mosses and ferns to shrubs, tree ferns and trees of all sizes. Ferns, mosses and liverworts will layer onto mossy tree trunks of koa, ohia lehua, ahakea, kopiko, kokio keokeo and other native trees and on the fibrous roots of fern trunks.
You can see this in a forest with no alien chompers, stompers, munchers and tramplers — no feral pigs, goats, sheep, deer, rats, cats and humans.
In your own garden, you can replicate this and the plants will be happy. If you do it right, it’s super easy, fun and you can save time that would have been spent mowing a grassy lawn.
Kupukupu fern, or Nephrolepis cordifolia, is one native that will go nuts and really seem to take over, especially if you fertilize with cheap, high-nitrogen or chemical-intense fertilizer.
Just trim back the dead fronds of the kupu and finely chop them to make mulch. Compost and leafy mulch are really the best way to nurture your soil and your precious native Hawaiian plants. Plus this keeps the green waste out of the landfill.
Stone mulch is another great tool to prevent weeds, conserve moisture and make a pretty display for your garden. Coarse red or black cinder, blue rock chips, river or moss rocks all help you have a nice garden that is easy to maintain and sustain.
You can also use cheap alfalfa pellets to nurture your hapuu tree ferns. Put two or three pellets up into the crowns of the hapuu and water well. When you water hapuu, gently put water on the fronds and the trunk. The trunk is actually made up of fibrous root-like structures.
Keep the lawn grass away. Alien lawn grass is very aggressive and will compete for water, nutrients and space. Turf grass even changes the soil microbiology for its own benefit and to the detriment of native plants and trees.
Another really nice native fern is the kupukupu lau nui, or Nephrolepis exaltata. This is a softer, taller fern than kupukupu, a much slower grower. It is a lighter, golden shade of green that contrasts nicely with other ferny green colors in the garden. We just planted some at the entry of Puohala Elementary School in Kaneohe in a large ohana-, community- and Pro Bowl-sponsored planting ceremony.
For those who like hapa-haole gardening, anthuriums and orchids also love to grow on and under hapuu tree ferns. Gardeners in Hilo and along the road to Volcano are famous for this kind of mixed planting. Check it out and be inspired the next time you travel to Hawaii island.
This makes for a gorgeous floral display, an easy to maintain garden with vibrant tropical color. Place the anthuriums in pots under the tree ferns. Orchids like honohono can be grown on the trunks of the hapuu. Cattleya orchids, the big fragrant, corsage type of orchid, enjoy shade and grow well on the trunk of hapuu.
If dendrobium orchids are your thing, keep them in the pots, and put them in sunnier areas around the hapuu planting.
Heidi Bornhorst is a sustainable landscape consultant specializing in native, xeric and edible gardens. Reach her at heidibornhorst@gmail.com.
