A rain garden is a landscaped area that is designed to capture and absorb rainwater runoff from hard surfaces like driveways, roofs, and walkways. Rain gardens can vary in size and can be an effective way to reduce the amount of polluted runoff entering our waterways. Soil microorganisms and plant roots capture and break down pollutants, while the now cleaned water soaks further into the water table below instead of washing down the storm drain system and carrying dirt and pollution to our ocean. In partnership with the City and County of Honolulu, MM installed and actively maintains a rain garden at Koko Head District Park hosting volunteer workdays once a month. To participate in an upcoming rain garden workday, please email lbailes@malamamaunalua.org for more details and to RSVP.
Photo Credit: Buddy Morris
Our rain garden benefits Maunalua Bay by…
1) Reducing flooding by absorbing rainwater from hard surfaces such as roofs, parking lots, and roads.
2) Preventing the pollution of streams and nearshore waters by filtering out oil, grease, and other toxic materials.
3) Recharging groundwater aquifers by allowing water to soak into the ground instead of being directed into the storm drains and washed out to sea.
Rain Garden Plants
ʻAʻaliʻi
(Dodonaea viscosa)
ʻAhuʻawa
(Cyperus javanicus)
ʻIhiʻihilauākea
(Marsilea villosa)
A’aliʻi is a versatile plant native to Hawaiʻi that can be found from sea level to high elevation of all the Hawaiian islands. The plant can be used as a specimen plant, hedge, or wind block. ʻAʻaliʻi is drought-tolerant, deeply tap-rooted, and historically used for medicinal purposes, tool-making, dye, and fishing bait. It’s fruit is used to create beautiful lei and floral arrangements.
ʻAhuʻawa is a sedge plant found in tropical Africa, Asia, and Hawaiʻi except for Kahoʻolawe. They typically grow in marshes, rocky coastal areas, and near streams, and its fibrous roots make it an effective plant for controlling erosion. The ancient Hawaiian’s utilized the plant’s pounded and dried stems to create fibers to strain pulp out of coconut and ʻawa. They prefer moist soil and full sun and can be found in marshes, streams, pastures, and coastal sites.
ʻIhiʻihilauākea resembles a four-leaf clover, but it is actually a small endemic fern found only on Oʻahu and Molokaʻi. It shares its name with the crater at the western end of Hanauma Bay, where it naturally occurs, and with an aliʻi wahine (female Hawaiian royalty) from Waimānalo who lived there and was celebrated for her beauty, kindness, and skills in fishing and surfing. Unlike many plants, this fern does not produce flowers and typically grows to only about six inches tall. As an endangered, endemic species naturally found in this area, ʻihiʻihilauākea is a meaningful addition to the rain garden.
ʻIlima
(Sida fallax)
Kokiʻo ʻula ʻula
(Hibiscus kokio subsp. st.johnianus)
Lonomea
(Sapindus oahuensis)
ʻIlima is an indigenous plant recognized by its delicate, bright orange pua (flowers). It is the official flower of the island of Oʻahu and is traditionally used to make lei ʻilima. ʻIlima grows in dry and damp forests throughout Hawaiʻi, from sea level to higher elevations. Once established, it requires little water and is highly adaptable, tolerating heat, drought, wind, salt spray, and a wide range of soils, making it an excellent choice for native landscaping and ecological restoration.
This Hawaiian hibiscus variety has thin-petaled red flowers that bloom continuously. In Ancient Hawaiʻi, its wood part was used to make high-quality charcoal, and flowers were used to make lei. As a medicine, kokiʻo was used for blood purification and as a laxative. This shrub/tree plant is a suitable hedge or screening plant in a Hawaiian landscape and is tolerant of drought.
Lonomea is an endemic soapberry tree found only on Kauaʻi and Oʻahu. It grows in moist to dry forests and produces hard, inedible black fruits. Traditionally, the fruits were used in lei making and lāʻau lapaʻau (traditional Hawaiian medicine), while the wood was carved into spears and other tools. Lonomea is monoecious, meaning each plant produces both male and female flowers. Its drought tolerance and ability to thrive in full sun make it well suited for rain gardens and native landscaping.
Maʻo
(Gossypium tomentosum)
Maʻo Hau Hele
(Hibiscus brackenridgei)
Maʻu ʻaki ʻaki
(Fimbristylis cymosa)
Maʻo is an endemic cotton plant found on all the main Hawaiian islands except for Hawaiʻi Island. It thrives in hot, dry, and windy areas near the coast and requires full sun and well-drained soils to grow properly. The yellow pua (flowers) are delicate, opening in the morning and closing by the next day. After being pollinated, the flowers develop into hard seeds that crack open to reveal brown cotton balls. The pua were traditionally used to make a green dye. The tendency for maʻo to thrive in Hawaiʻi’s harsh, dry leeward environments make it a great plant for this rain garden.
Maʻo hao hele is an endemic and endangered plant species that grows in dry to mesic forests of most Hawaiian islands except Niʻihau. It requires minimal watering and thrives best in full sun to partial shade. The plant produces two flowering periods yearly, each lasting up to two months. This plant is ideal for use in containers, as accents, or as specimen plants.
Maʻu ʻakiʻaki is an indigenous sedge with green leaves and distinct brown flowering spikelets. It thrives in dry, rocky coastal habitats and is well adapted to harsh conditions like extreme heat, salt spray, and strong winds. Although there are no known traditional uses for the plant, it is highly valued today for its drought tolerance, hardiness, and ability to stabilize soil, making it an excellent groundcover for erosion control in coastal restoration projects.
Milo
(Thespesia populnea)
Nanea
(Vigna marina)
Naupaka kahakai
(Scaevola taccada)
Milo is a large coastal tree recognized by its yellow flowers with maroon centers. Believed to have been introduced to Hawaiʻi by early Polynesian voyagers as a canoe plant, milo was highly valued by Kānaka Maoli. It provided shade, its flowers were woven into lei, its fruits produced a yellow-green dye, and its durable wood was carved into bowls and utensils. Today, its drought tolerance and ability to thrive in a variety of soils make it a popular choice for ecological restoration and erosion control in dry, coastal areas.
Nanea is an indigenous vine found in dry coastal areas on all the main Hawaiian Islands except Lānaʻi and Kahoʻolawe. It is recognizable by its bright yellow, pea-shaped flowers. As a nitrogen fixer, nanea converts nitrogen from the air into a form plants can use, making it a good companion plant. It thrives as a groundcover in open, sunny areas where it has plenty of room to spread. In lāʻau lapaʻau (traditional Hawaiian medicine), the leaves, stems, and stalks were pounded and applied to wounds and hēhē (boils, sores, and ulcers).
Naupaka kahakai is an indigenous coastal shrub found on all the main Hawaiian Islands. It is highly adaptable and low-maintenance, thriving in a variety of conditions but growing best in dry, sunny areas with little water. The plant produces small whitish-purple flowers with petals on only one side. According to a well-known Hawaiian moʻolelo (story), the half-flower represents two lovers who were separated: Naupaka kahakai was banished to the beach, while naupaka kuahiwi was sent to the mountains. Together, their flowers form a complete blossom.
Pōhuehue
(Ipomoea pes-caprae)
Puakenikeni
(Fagraea berteroana)
ʻUhaloa
(Waltheria indica)
Pōhuehue is an indigenous Hawaiian vine found on sandy coastlines throughout the Hawaiian Islands and in tropical and subtropical regions around the world. This fast-growing plant thrives in dry, sunny coastal habitats, where it serves as an effective groundcover that helps stabilize sand and reduce erosion. It is easily recognized by its pink-purple, morning glory-like flowers. Traditionally, nearly every part of the pōhuehue was used in lāʻau lapaʻau (traditional Hawaiian medicine), and surfers would slap its vines on the ocean’s surface as part of a traditional practice believed to bring a bigger swell.
Puakenikeni was introduced to Hawaiʻi from the South Pacific in the late 19th century. Its Hawaiian name, meaning “ten-cent flower,” comes from a time when each blossom sold for ten cents. It thrives in full sun and humid, wet conditions but can also grow well in drier areas with adequate irrigation. Because it is difficult to propagate naturally, puakenikeni is not considered invasive in Hawaiʻi and is primarily grown as an ornamental tree in home gardens. It is included in this garden for its cultural and traditional value to the community, and because it provides pollinators, won’t damage nearby concrete structures with its roots, and, as a tree, offers shade.
ʻUhaloa is a native shrub found throughout the main Hawaiian Islands in dry, sunny habitats. It can grow as an upright shrub or spread along the ground, though individual plants typically live for only about five years. In lāʻau lapaʻau (traditional Hawaiian medicine), ʻuhaloa has long been used to help treat sore throats, asthma, and other ailments. It is drought tolerant, adaptable, and low maintenance.
ʻUki ʻuki
(Dianella sandwicensis)
ʻŪlei
(Osteomeles anthyllidifolia)
ʻUkiʻuki is a grass-like plant found throughout the main Hawaiian islands and is easily identifiable by its vibrant blue-purple berries. It grows in a variety of habitats including dry or wet forests, lowlands or highlands, and shady or sunny areas. Kānaka Maoli traditionally used the berries as a natural dye for kapa and wove the leaves into cordage and thatching for hale (houses). As a highly adaptive and relatively low-maintenance plant, ʻukiʻuki is a valuable addition to the rain garden.
ʻŪlei, also known as the Hawaiian rose, is a resilient native shrub found on every main Hawaiian Island except Niʻihau and Kahoʻolawe. It thrives in diverse habitats, from coastal cliffs and lava fields to lowland forests. Traditionally, Kānaka Maoli used its strong wood to make tools such as ihe (spears) and ʻōʻō (digging sticks), while its leaves, fruit, and flowers were used in lei making, traditional medicine, and as a food source. Today, ʻūlei is valued in restoration projects for its drought tolerance and ability to help reduce erosion.