Miscellaneous Tips on Planting, Watering, Weeding,...
Below is a mixed collection of tips we've learned or acquired over the years that, hopefully, will increase your success at growing and using native Hawaiian plants.
Miscellaneous Tips on Planting, Watering, Weeding,...
Below is a mixed collection of tips we've learned or acquired over the years that, hopefully, will increase your success at growing and using native Hawaiian plants.
Don't Disturb the Roots!
Native Hawaiian plants have existed for thousands and thousands of years without any large land animals; the largest is believed to be a now-extinct flightless goose about the size and weight of a turkey. Because of this, Hawai‘i's native plants never needed to develop robust roots — roots capable of enduring the weight of heavy animals above them. This history comes into play when planting a native Hawaiian plant in the ground, as well as during transfers from one container to another (e.g., seedling tray to individual pot). Root sensitivity varies between species. For example, ‘ōhi‘a lehua (Metrosideros polymorpha) are particularly intolerant of any root disturbance and need to be transplanted with extra care. In contrast, a wiliwili (Erythrina sandwicensis) tree can recover from dramatic root damage. Because of this variability, the standing rule when planting or transferring any native Hawaiian plant is, "Do Not Disturb the roots!" since any disturbance could potentially damage the root system and kill the plant.
Common disturbances that should be avoided include:
Removing a plant from its pot before digging the hole you wish to transfer it to. Removed from their pot, a plant's roots are directly exposed to the drying effects of the open air, wind, and sunlight. This can very quickly and seriously damage the plant's roots. Therefore, you should always try to minimize this unnatural exposure.
Aggressively squeezing the pot to make it easier to remove the plant from the pot. Instead, push (extremely) firmly on the bottom of the pot to "pop it out," or use a pair of scissors to cut the bottom and sides of the pot to make removal easier. Your native Hawaiian plant is far more valuable than the pot it is in!
Once removed from the pot, separating and spreading the roots before planting. This should not be necessary unless the plant's roots are severely potbound, in which case, pruning the roots and repotting is a better option. You can then plant later after the plant has recovered in the pot.
Digging a hole too small or too shallow for a plant's roots, and then trying to squeeze the roots into the hole or leaving the surface roots exposed to the air.
Pulling on the stem of a seedling to transfer it from a communal germination tray. Rather, gently pull on a seedling's leaf while getting beneath its roots with a finger or small tool.
Improving Soil Drainage
Many plants, both native Hawaiian and non-native, do better in soil that drains water easily. So, what do you do if the soil at your site does not drain well? Well, unfortunately, we have come across far too many gardening websites and books that give bad advice on this topic. Most often their guidance is similar to this: "To improve drainage, consider added amendments like gravel, cinder, etc., to the planting hole." The problem with this advice is obvious if you think about it. Where is the water going to drain to if all the soil surrounding your planting hole is still incapable of absorbing and dispersing the water? It's like trying to drain a swimming pool by filling the pool with rocks. So, what's our advice?
To improve the drainage of your planting site, work with gravity. Pile up the soil at your site into mounds or ridges so excess water, pushed by gravity, will drain out of the mound or ridge where your plant is planted. You can further enhance this drainage by adding cinders, gravel, sand, etc., to the mound or ridge. (Just adding these amendments to the soil while keeping the site flat will do little to improve drainage.) One place to see this technique with dramatic effect is the Maui Nui Botanical Gardens. There, many of the native Hawaiian plants are planted on mounds of primarily black cinder, and they seem to love it. (The underlying soil in the Gardens is sand and clay.)
Be Careful with Mulch
If you are originally from the mainland, it's unlikely you ever experienced any downsides to using organic-based mulch (e.g., wood chips, leaves) in your garden or landscape. Rather, this type of mulch provided multiple benefits such as:
Suppressing weeds.
Adding nutrients and structure to the soil as it decomposes.
Improving the moisture retention of the soil.
Shading and thus cooling the soil in summer, and insulating and keeping the soil warmer in fall, winter, and spring.
Promoting the growth of beneficial organisms such as mycorrhizal fungi and predatory nematodes.
Unfortunately, while landscapes in Hawai‘i share these benefits, there are also two serious downsides to using organic-based mulch. These are:
Since its first detection at Pearl Harbor in 2013, the alien Coconut Rhinoceros Beetle (Oryctes rhinoceros; CRB) has spread throughout O‘ahu and has been recently (2025) seen on Kaua‘i, Maui, and Hawai‘i. This pest attacks and kills palm trees (native and non-native) as well as other plants like hala, banana, sugarcane, and kalo. CRB will lay their eggs in any decaying plant matter, where the larvae feed and grow, and both organic-based mulch and compost are ideal habitats for CRB larvae.
Many native Hawaiian plants lack immunity or resistance to harmful alien microbes (see Soils & Media introduction). These microbes can be imported into a garden or landscape via mulch obtained from other locations. Think about it: "If the mulch you just imported was made by chipping up a tree or shrub, was that tree or shrub healthy or diseased?"
Our advice, if you decide to use organic-based mulch, is to recycle the organic material within your own garden or landscape and resist the temptation to import it. Further, keep a watchful eye for any evidence of CRB infestation in your space(s). And, if you find any, reconsider your use of organic mulch, perhaps, switching to something inorganic like cinders. Refer to this website for more information on CRB in Hawai‘i.
Consider the Plant's Natural Habitat Before Planting
Many people make their landscape decisions based on aesthetics and functionality while giving only minor consideration to the plants' environmental needs. This is fine for most of the alien ornamentals for sale at your local garden shop, since these plants have undergone decades of artificial selection to widen their environmental tolerances. This is not the case for nearly all our native Hawaiian plants. Unfortunately, many (but not all) of our native plants will grow poorly or even die when placed in a site with environmental parameters (e.g., light, temperature, soil moisture and composition) outside the range they would experience in their natural habitat.
Planting your native Hawaiian plants smartly, so they are in an environment that matches what they experience in the wild, will not only improve the growth and health of your plants but will also decrease the time and effort you spend engaged in plant and landscape maintenance. For example, consider these nine native Hawaiian plants: ‘ākulikuli, ‘ilie‘e, koa, kuluʻī, maile, maiapilo, ‘ōleho kai, palapalai, and wiliwili. Planted randomly, or purely based on aesthetics and functionality, you're likely to end up with a lot of 'unhappy' plants and lots of extra work trying to keep them healthy and alive. Instead, if you grouped and planted them in three separate sections of your landscape, you would end up with 'happier' plants and less work. Can you guess which of the three sections each plant should be planted in? If you grouped the ‘ākulikuli, maiapilo, and ‘ōleho kai together in a coastal section, the ilie‘e, kuluʻī, and wiliwili together in a dry forest section, and the koa, maile, and palapalai together in a mesic forest section, you would be absolutely correct!
Planting native plants with similar environmental needs together makes it easier for you to care for them. For the nine-plants example above, you can now select the best spot in your landscape for each of the three groupings (e.g., the coolest, shadiest site for the mesic forest group). You can also install an irrigation system for each section (or set up a manual watering schedule) that perfectly matches the amount of rain each plant would experience in the wild. Lastly, you can amend the soil in each section to more closely match that of a wild location (e.g., adding crushed coral and sand to your coastal plant section). All in all, the lesson here is: consider the plant's natural habitat BEFORE you place it in the ground.
Be Cautious About Medicinal Uses
Within each of our plant webpages, we have included a section on the recorded uses of that plant, including medicinal uses. However, when it comes to how Hawai‘i's native plants were used for medicine, it is impossible in many cases to separate accounts of pre-contact (i.e., pre-1778) medicine from post-contact medicine. Anyone who knows Hawaiian history knows that after European contact, Hawaiians were assaulted by a myriad of new fatal and non-fatal diseases. We also know immigrants from China, Japan, and other countries, primarily brought to Hawai‘i as laborers (because so many Hawaiians were dying), brought with them many new treatments and "cures" for old and new illnesses. Undoubtedly, desperate Hawaiians learned about and used these treatments, and thus, the division between ancient Hawaiian medicine and post-contact Hawaiian medicine was subsequently blurred. Therefore, we ask you to be cautious in using our website to assert that, "Ancient Hawaiians used so-and-so native plant for this-or-that illness," because, frankly, we will likely never be able to completely separate ancient Hawaiian medical knowledge from more recent practices.
Be Careful Removing Weeds
Ever present, weeds can be problematic and destructive for any plant grower. It is usually safest to remove them by hand from any area with native plants, especially weeds growing near the base of a native plant. For vining weeds, cut the vine in numerous places before attempting to remove the cut sections, since removing an intact vine all at once can seriously damage a native plant. For vines (e.g., ivy gourd, asparagus fern) that can extensively cover trees or shrubs, you might want to cut the vine near the bottom and allow the upper portion to die and deteriorate, rather than try pulling it off, which could severely damage the native plant.
Spraying with commercial or DIY weed killers should be done selectively and minimally. Always follow the directions on the label, and be mindful of weather conditions to avoid wind-drift carrying the spray to sensitive native plants. Avoid any type of drenching weed killers since the soil will retain residues that may last for a long time and adversely affect future plantings. Also, these weed killers can leach down through the soil and pollute water reservoirs below.
For weed control, we encourage you to use mulch made from the native plants on-site or cinder. Avoid any imported mulch for the reasons described above (i.e., Be Careful with Mulch).
If neither native plant or cinder mulch is feasible, try using weed-cloth if you don't mind its appearance; why can't someone make a weed-cloth that looks like soil! However, DO NOT cover the cloth with any type of mulch because the mulch will quickly degrade into weed-promoting soil. Additionally, lay down and secure small sections (a few feet wide and long) of cloth rather than one or two large sections, since these smaller sections can be more easily replaced if they become torn or deteriorate over time. Do not get lazy and cover old weed-cloth with new since this will seriously reduce water permeability into the soil beneath. Lastly, be aware that weed-cloth greatly diminishes the underlying soil's ability to renew itself with organic matter (e.g., leaf litter) and nutrients. Over time, this can have undesirable effects on the plants growing in the area (e.g., reduced soil aeration). Therefore, consider renewing the soil with compost or other types of organic matter every time you replace the cloth.