Question: I bought some hapuu tree ferns at a home improvement store. What do I do to grow them? Put them in water? I live in lower Kalihi and my soil is kind of clay like. Should I add cinder to the planting puka? — Raymond, Kalihi
Answer: First, get some good quality mulch like monkeypod leaves, or buy some locally made mulch such as Menehune Magic in the purple bag from Hawaiian Earth. Cinder is also good to help your clay soil drain better.
Decide where you will plant the hapuu. They can be kind of close to each other if you spin them around and orient them to space where the new fronds will unfurl. In a small yard, you can space them three to four feet apart. The emerging fronds will make room for one another, just like they do in the Hawaiian rain forest. Place them at least five feet away from your house or from walkways.
Get rid of any lawn grass by smothering it or digging it out by the roots. Grass is competitive with other plants, especially native ones like our hapuu tree fern, which is also known as “mother of the forest.” This name was given because all kinds of plants like to start life in and around moist hapuu trunks, including ohia lehua, olapa and other kinds of ferns or small moisture- and shade-loving plants.
Make a nice mound of compost and cinder and mix them together. Dig the planting hole using just the soil in your yard and keep the mulch mixture on the side. Plant the hapuu trunk about four to six inches deep. Tamp down the soil to help the tree fern stand up. Take the mulch mixture and make a ring around the trunk, keeping it at least three inches away from the trunk.
Soak the mulch and water the soil well. The trunks of tree ferns are made up of aerial roots — that’s how they get a lot of the moisture they need to grow and thrive. Water the top of the fern trunk and the unfurling new fronds. Water your hapuu at least once a day. Mornings are the best time to water, but a good soaking when it fits in your schedule is important, especially for newly planted ferns.
Hapuu can grow and thrive in sunny places if you keep them watered. The soil is important, too. Try to replicate a rain forest soil for your Hawaiian forest plants. The soil in your Kalihi yard was probably originally a rain forest soil before the land was cleared and the topsoil scraped off to build houses. (Most yards in Hawaii have terrible soil for growing plants because you need a different kind of soil structure to have a solid foundation for your house.)
After your hapuu has grown a bit and some of the fronds have unfurled and developed, you can fertilize them with cheap alfalfa pellets or rabbit food. Put two or three pellets on the crown of the plant (around where the new fronds unfurl) and water them well. This is a cheap, good organic source of nitrogen for your ferns. Fish emulsion fertilizer is also great for ferns but has a strong “hauna” smell.
We have five kinds of hapuu in Hawaii and all of them are endemic (native and unique to Hawaii). They are beautiful in home gardens and will welcome you home to serenity after a hard day at work.
Hapuu grow slowly, even in the best conditions. In ideal conditions the tree fern trunks will grow about a foot every 10 years, so this is not a plant that will get too big. They also can help you create an ideal microclimate in your home garden.
You can plant other rain forest plants such as palapalai and palaa ferns, ohia lehua, shinobu or rabbit foot fern (a Japan native) or anthuriums (native to tropical America) close to your hapuu. Honohono, cattleya and nobile orchids grow well on the trunks.
Gardens in Hilo and the Volcano area are famed for these epic “hapa haole” plant combinations.
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Heidi Leianuenue Bornhorst is a sustainable landscape consultant specializing in native, xeric and edible gardens. Reach her at heidibornhorst@gmail.com.
