Hawaii’s Home Gardeners Can Adapt to a Changing Climate by Increasing Resiliency
Updated: Nov 18
The U.S. Drought Monitor is jointly produced by the National Drought Mitigation Center at the University of Nebraska-Lincoln, the United States Department of Agriculture, and the National Oceanic and Atmospheric Administration. Map courtesy of NDMC.
Severe Drought Predicted for upcoming Winter/Rainy Season
As we look into Hawaii’s climate and food future, we may be asking ourselves, how will the changing climate affect my ability to grow food or seed and what types of adaptations will be needed to create resiliency in my gardens or orchard? How is climate change in the Pacific affecting Hawaii’s weather systems? What is the forecast by the National Weather Service as most of the State moves from the dry to the wet season? How will these changes impact agriculture in Hawai'i and our backyard home food production?
I imagine many of you are interested in this topic. Glenn and I have been talking about this for a while now, and we want to share a few of our thoughts, as well as the latest National Weather Service predictions, and how this relates to growing food in your home garden for your table - especially during this upcoming Winter season.
You might want to keep a link to this blog for future reference, since there is a lot of resource information here for the home gardener in Hawai’i at the end of the blog. We need to prepare ourselves as soon as possible.
Our Senior Service Hydrologist for the National Weather Service (NWS) in Honolulu, Kevin Kodama, recently issued his forecast for the upcoming Wet Season Rainfall Outlook for the State of Hawai'i (October – April), unless of course you live in Kona, where the upcoming season could be the opposite. It looks like the El Nino event in the Pacific is likely to peak as a strong drying event through the spring of 2024 and will create severe to extreme drought across the Islands and affect weather worldwide.
To understand the El Nino/La Nina weather patterns in the Pacific here is a great summary from National Oceanic and Atmospheric Administration, NOAA.
Let’s take a look at a few of the observations Glenn has made over this past year on the Island of Molokai.
In Hawaii, there are really three seasons: summer (kau) from May to October, winter (hoʻoilo) from November to April, and sometimes both summer and winter at once.
The average daytime summer temperature at sea level is 85° F, while the average daytime winter temperature at sea level is 78°F (25.6°C). So, what happens if we have a dry winter - as is being predicted? This will mean less water will be stored in the aquifer with dryer watersheds, and if you are on catchment, it means less water for your gardens and trees.
Remember “the rain follows the forest.” Check out this short video by Jason Scott Lee.
This dryness can have a long-term impact on both surface and underground water, including moisture in our soil. The impact on the whole ecosystem is then uncertain and will most certainly shift insect species, disease incidence, and affect plant growth.
The photo above shows a spider mite infestation.
Weather is not consistent across the islands. A slight shift in the wind direction can make the difference between drought and an over-abundance of rain. A few years ago, the wind shifted to an easterly direction from a northeasterly ‘trade wind’ direction and this had a dramatic impact on the rainfall on Molokai with no rain from January to March 2022. Both Maui and the Hawai’i Island were blocking the ability of Molokai to receive rain and Molokai was in the rain shadow. Around the same time, a new pattern developed for Kona. Clouds carrying an abundance of moisture flowed up into the leeward side of Hawai’i Island from the equator and rainfall greatly increased throughout that rainy season.
The northeast trades blow about 60% or 3/5’s of the time and this goes back to records that have been kept since the early 1900’s. The islands are shaped by these forces with cliffs and mountains that capture clouds with rains unloading on the leeward slopes. About five years ago, trades dropped by 25%, and the result was drought followed by torrential rains from southerly and westerly storms. Slow moving storms like these wreak havoc on our environment and lead to excessive erosion and runoff into the ocean. The impact on the nearshore environment can be devastating.
In late January 2023, Molokai experienced a storm of a magnitude never seen in modern times with 28 inches dumping on the island from Friday afternoon to Sunday morning. Fifteen-foot piles of soil and boulders on the side of the road in East Molokai was the result. Many Hawaii valleys are narrow and steep, and this massive surface area along with elevation can create intense flash flooding. When storms occur with this kind of intensity, little can be done to prevent catastrophic damage to property and the environment. The nearshore environment turned dark brown then settled on the bottom, shading and clouding limu and reef fish. Some fish were found with dirt filling their gills.
The long-term effects of these weather events are not well understood and can create a shift in nearshore species dominance. Some prized limu are not as common as they were several years ago and this could be attributed to climate change, including drought, higher or lower than normal temperatures, and erosion. Toxins and nutrients originating on the land can find their way into the ocean and cause further disruption in sea life including bioaccumulation of toxins, and this was the case in Kalamaula on Molokai decades ago when higher than normal levels of arsenic were found in crabs. Storm water entering the Lahaina shoreline after the fire will create the same phenomena with toxins such as aluminum, mercury, cobalt, arsenic, pesticides, and others.
A volcanic eruption can disrupt island and statewide weather patterns by heating the air at high elevation and spew gases into the environment that can defoliate and kill plants downwind. High concentrations of sulfuric acid can acidify the environment and make it inhospitable for many plant species especially those with thin, delicate leaves. Weather shifts on the land can occur with warmer air temperatures at high elevation similar to a La Nina/El Nino occurrence where Kona can experience weather extremes, becoming unseasonably wet or dry.
Let’s take a practical look at how Hawaii’s gardeners can adapt to and mitigate the drier fall and winter season.
Strategies for Increasing Resilience During Drought Events - Covering the soil is the first step.
We know drought is coming. What lessons can be gleaned from these recent weather episodes? Covering the soil is the first step. Mulch will protect and hold moisture in your soils and over time continuously add nutrients as it breaks down in place.
Unprotected soil with temperatures of up to 130 degrees can cook plant roots and create nutrient deficiencies and uptake issues, and very few strategies can mitigate this extreme, but growing varieties with scavenging root systems can lessen impacts as long as you are deep watering versus light daily watering.
1. Mulch your gardens and cover the soil. One strategy is utilizing the leaf material in your landscape, thus returning carbon to the soil. Instead of composting landscape/garden material, strip the leaves and use them to cover the soil. If you want them finer, you can always run over them with your mower and catch the mulch in your bag. If you run plants or tree material through a chipper/shredder, use that as your garden mulch, as long as there is not too much woody material. You can also chop up guinea grass or other taller grasses like vetiver. These grasses have a high silica content and break down slowly. Soil mulch also increases water infiltration.
2. Local Genetic Diversity is important. Remember seeds can take environmental conditions into their genetics and alter themselves over time to better deal with temperature, humidity, drought and rainfall conditions. That is why locally grown seed, or your saved seed can become a climatic strategy. Experiment with different varieties.
3. Deep watering 2-4 times each week verses light daily watering. Get to know your soil moisture content as soils are different. How can you tell moisture content? Put your finger down a few inches into the soil and feel it. During Kona's dry season I water once a week because the soil does have quite a bit of organic matter, which helps to retain moisture. Water either late in the afternoon or early in the morning. Wet soil at night in some soil types can create fungal and bacterial problems - observe & adjust. If the soil feels moist wait another day or so before watering deeply.
4. Plant drought tolerant crop varieties that you like to eat and want to grow where you live, plant the hardy ones you already know. Ask other local gardeners what varieties are working in their gardens.
5. Either get started or continue building compost piles on your farm or home garden. Place them in a shaded area, and mix green and brown materials. Keep an eye on the moisture level of your compost piles, you may need to water them well if there is no rain and keep them covered with a layer of mulch or a tarp. Finished compost, when added to your soil, raises the moisture holding capacity of your garden beds.
6. Keep an eye out for invasive species. Every Island has an Invasive Species Committee and website that will alert you who to watch for. Drought can create new opportunities for invasives.
7. Shading areas as a strategy for growing and preserving soil moisture. An example would be growing a few pigeon pea tree/bushes (that is both nitrogen fixing and drought tolerant) or other taller nitrogen fixing bushes in your garden beds to provide some light shade for plants needing consistent moisture, like kalo.
8. Get a soil test. Growing a garden or a farm without a soil sample is like baking a cake without a recipe; it's a hit or miss. Having a soil sample to guide you in what nutrients to add to your soil is critical. Do you need to increase your pH or just increase the calcium content? Too much is just as bad as not enough. A good tip would be to take a soil sample from your best spot and your worst spot and that can lead you to what's lacking or in excess in your garden. Also, adding compost regularly to your garden beds will help to balance nutrients in the soil and help it retain moisture during dry times.
9. Sloping areas are especially problematic and require conservation actions that can include the creation of swales to capture or slow the movement of water, speed bumps on dirt roads to divert water off the road to prevent washouts, and planting ground covers and grasses such as natives and perennial peanut, as well as banana, vetiver, and lemon grass. The list is long and will depend on your elevation, rainfall, and prevailing temperatures.
10. For extreme coastal environments, look to salt-tolerant grasses such as wild Bermuda or seashore paspalum (photo, right). Look for utility in all the plants you grow, and under the present extremes, you have to plant the most resilient ones and sacrifice ones that require too much pampering.
11. Create a Garden Log/Journal. Start keeping observations on weather, crop variety, time of year planted, watering, etc. in a notebook.
12. Agroforestry gardens. Creating gardens within your orchard area increases bio-diversity and provides some light shade, increasing the health of both systems.
13. Work in the garden or orchard in the earlier or later part of the day. Use appropriate sun protection.
14. Harvest Rain Water! The NWS is predicting that with the upcoming drought there will also be “rain events.” That is the perfect time to gather rain water for your garden. I like using a trash can under one of my gutter spouts. Rainwater is live water and very beneficial for plant growth.
Grasses have gotten a bad rap lately with the Lahaina fires, but we need to look at the totality of the situation and what is at the core of the issue - and I would have to say it was the wind. Wind is a great destroyer and in and of itself can have an adverse environmental impact. Wind can have a detrimental impact on flowers, and since flowers produce fruits, the impacts can include misshapen fruit, poor or no pollination, and also torn leaves and damaged root systems. Finding the ideal windbreak for your area takes a lot of observation including a better understanding the pros and cons of each crop species. Water needs, drought tolerance, management time and costs, and minimal root invasiveness are some of the criteria. The right windbreak will reduce wind speed and help protect crops during wind/hurricane events. I’m considering native hibiscus for infield windbreaks after watching their habits for 15 years!
Planning down the road becomes more important than ever before in crop selection.
Short, medium, or long-term planning strategies are important. For the vegetable farmer or gardener, planning 2-3 seasons ahead is probably a good idea because anything can happen. Start a Garden Log and make notes about your seasonal weather patterns and seed varieties that are either working well for you or not.
What we learned from COVID (and should have known for a long time!) is 'you cannot harvest if you don’t plant' and ‘you can’t plant if you don’t have seed’. So basic but too easily often overlooked!
A Planting Strategy Now and for the Future
Embrace the strategy of planting everything in each season, except for the extreme crops that will only grow in summer and winter. ‘You never know if you never go!’ is my mantra. If you didn’t plant a certain crop, you’ll wish you did after season’s end. Be sure to keep track of your successes and failures in your Garden Log.
In our new normal, winter is the time for winter crops but also a good time for some of the summer crops with the exception of watermelon, edamame, and corn, but I do know someone who harvested some pretty good watermelon at Christmas time several years back, so there are always exceptions to the rule!
Consider Starting right now and over the next few months: peppers, eggplant, tomato, green and bulb onions, lettuce, all leafy greens, squash, pole and bush beans, peas, beets, won bok, pak choy, kai lan, kai choy, radish, carrots, and daikon, broccoli, herbs, and countless other varieties.
One More thing…Climate Smart farming doesn’t have to mean using expensive technology.
It could just mean more environmental observation ('ike), common sense, using resources (see below) to see how other farmers and gardeners are adapting around the world, checking in with gardeners in your neighborhood, and pondering what is best for your place in the sun. Weather predictions can go very wrong and we really don’t know which way the weather will shift because too many factors are at play. Whether it’s El Nino or La Nina, hot or cold, wet or dry, life goes on and having some degree of food security can make the difference between survival and famine in the most isolated string of islands on the planet.
As we begin adapting to the new weather patterns and unique challenges on each Island, let’s find a way to share our best practices with each other. There is an amazing amount of knowledge collected in the customers of the Hawai’i Seed Growers Network Online Marketplace. Growing food for our families continues to increase in its importance year after year, as prices continue to rise and selection and quality decrease. Fresh food is the basis of our health and the health of the next generation. Mahalo for all your contributions to building a robust and resilient community food system across Hawai’i. Please use the comment section at the end of the blog to share your thoughts and experiences with all of us. Mahalo!
Additional Reports and Resources – All Apply to Home Gardening
1. A New Report from two of our UH Agroecology Professors, Hector Valenzuela UH Manoa & Albie Miles UHWO, "Agroecology: A Pathway to a new Model for Agriculture in Hawaii.” This paper makes a case for the conversion of agriculture in Hawaii towards Agroecology, a scientific system of agriculture that is based on ecological concepts and principles as well as on social values that promote food sovereignty, affirmation of indigenous and cultural identity, and rural economic well-being.
2. An interesting report has just been published by a team of scientists from UH and UC Santa Barbara titled “Climate Change and Perceived Vulnerability: Gender, heritage, and religion predict risk perception and knowledge of climate change in Hawai’i.” They interviewed people from Hawai’i Island for this report on their knowledge and level of preparedness regarding climate change.
3. Another resource has just been published from Western SARE titled: “Adapting to a Changing Climate: How Western SARE is meeting the Needs of a Warming West.”
4. A new report by Miguel A. Altieri Agroecology Professor at UC Berkley “Agroecology & Climate Change: The Limit of Socioecological Resilience”
5. Lastly, a very informative video on Dry Farming in Latin America given by Agroecology Professor Clara Ines Nicholls UC Berkley. “Agroecology and the Design of Climate-Resilient Agricultural Systems.”
From all of us at the Hawai’i Seed Growers Network - a hui hou, until next time.
Glenn Teves has worked in as a CTAHR Extension Agent on Moloka’i for 42 years and hopes to retire by the end of 2023. His family has a 10-acre homestead at Ho’olehua and farm approximately 2-1/2 acres planted in taro, ulu, papaya, banana, avocado, pomegranates, figs, assorted vegetables and vegetable seeds. A year ago, they fenced 6 acres with 8-foot fences to control deer which have been a huge agricultural challenge for the past 15 years. They also just opened 3 additional acres by mowing 6' high guinea grass that has provided them with a lot of organic mulch. One of his future projects will be venturing into growing flower seeds. Glenn shares his expertise with many community educational projects and grows seed for the Hawai’i Seed Growers Network.
Nancy Redfeather retired from statewide Farm to School and School Garden work at The Kohala Center in 2016. Since then, she has been building gardens, growing seed, and experimenting with variety and culinary creations on her family farm at Kawanui in mauka Kona. She and her husband Gerry recently finished a 2-year SARE “Table Grapes for Hawai’i research project. You can see all their work at www.kawanuifarm.org
If you have questions about this blog or the upcoming winter season email Nancy at email@example.com