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  • Michelle Carrillo

Planting for the Season

Updated: May 27, 2022

The days are lengthening, mornings are starting earlier in the day and sunsets are lingering in the evening sky. Daytime temperatures are rising, and the shortening nights are warming up. Tradewinds have been noticeably picking up as Hawai'i moves into hurricane season - June through November.

Summer is a great time to garden in Hawai’i.

It helps to know what cultivars to focus on and which to avoid during the summer season. It also helps to have many hands during the warmer days and since the keiki are home from school, it’s a good time to gather the family and get the garden beds dug and planted.

As the days warm up it’s good to focus on heat loving plants that need these long days to flower and seed, producing the abundant cornucopia you want to bring to your dinner table.

Think corn, squash, tomatoes, peppers, onions and heat loving greens.

If you haven't gotten your corn into the ground yet, this is the perfect time to get seeding - you will want to wrap up your final corn planting by the end of July or early August. At the Hawai'i Seed Growers Network Online Marketplace we have two hard to find heirloom popcorns, Dynamite and Japanese Hulless, that taste much better than store bought popcorn and are just so much fun to grow and pop! We also have two sweet corn varieties available from the lineage of Dr. Brewbaker, Hawaii's renowned corn breeder at UH Manoa. The Brittle 9 comes from a selection of Dr. Brewbaker's famous #9 sweet corn (and is outrageously sweet and delicious!) and the Brittle 2, described by Dr. Brewbaker as "our best genetic base", is designed for broad disease and pest resistance.

Tomatillos and poha berries are old favorites across Hawaii's gardens as they are easy to grow and will ramble across your yard for an extra long season of sweet and sour tangy fruits. Plants can last a year or longer with care and are often happy to receive a good pruning, recovering with strong leaf growth and another round of fruit set. These easy to grow varieties are a great snack source for garden grazing! Tomatillos, tomatoes and peppers thrive during long, hot summer days and will keep your kitchen in good supply to make delicious salsas, pesto, and chili paste.

Peppers planted in May will start fruiting mid to late July and can bear fruit continuously for up to two years. Peppers enjoy being supported with a general fertilizer during periods of heavy yields and they especially appreciate receiving support for branching arms bearing heavy loads of fruit. Good nutrition, weed management and staying up on harvesting will help to deter pests and disease issues. The Hawai'i Seed Growers Network Online Marketplace has many varieties of sweet peppers and a few that have proven to have disease resistance to Hawaii's challenges while producing abundant and delicious peppers.

The Ka'ala pepper (pictured above left ) is a medium to large sweet, red bell pepper that was released by CTAHR in the early 1990's with excellent bacterial wilt resistance and resistance to root knot nematodes. Small plants offer high yields of thick walled, sweet red bell peppers. Staking or trellising is needed to support branching arms.

Hawaiian Sunray (pictured above middle) yields an abundance of yellow sweet peppers on plants that are small, stocky and productive.

The Ala Ka La Pepper (pictured above right) is a cross between Ka'ala and Hawaiian Sunray and shows strong signs of disease resistance. With the Ala Ka La pepper cross you can expect to see variation in fruit size, color and shape.

We have a handful of hot pepper varieties available at Hawai'i Seed Growers Network:

1) Nana's Fingers, a Serrano type that makes an excellent chili paste (pictured at left),

2) Datil hot pepper, a fruity, yellow pepper from Florida, and

3) a Mystery Chili Pepper - a New Mexico type of hot chili grown in Molokai that is excellent for dried pepper wreaths.

Tomatoes can face many disease and pest issues. The key to managing pests and disease control is to start with quality locally adapted seed that has built in disease resistance. Sanitation is also very important. Disposing of damaged fruit at the base of a plant will allow pests to complete their life cycle and return to attack the crop. The warm nights of summer can be difficult for tomatoes and can attract bacterial or fungal conditions. It is especially important during the summer months to give plants plenty of space (minimum 3' between tomatoes) and provide good air circulation or wind flow to help plants dry quickly between rainfalls or waterings. At Hawai'i Seed Growers Network we have found that the GoFarm Gold Cherry Tomato can stand up to disease and produce a quality crop when other tomato varieties succumb to a heavy bacterial load. The AVTO 1350 Tomato, bred by the Taiwan World Vegetable Center, has genetic resistance to Tomato Yellow Leaf Curl Virus and Tobacco Mosaic Virus. If you don't have a heavy load of disease issues in your area you can try one of the many Heirloom cherry tomato varieties available at the Online Marketplace or the large slicing Heirloom Old Brooks tomato.

Leafy Greens

The long days of summer can be difficult for leafy greens, but if you select your varieties well and place them in an appropriate spot in your garden you can pull off a crop without too much time spent managing hoses or drip lines. This is a great time to try the Red or Green Calaloo amaranth green. This nutritious leafy green tastes a lot like spinach and is very easy to grow. Striking plants can get 4-5 feet tall, producing handfuls of leaves for your kitchen throughout the season.

Expect the Carinata kale to outpace cool weather kale varieties and thrive in the long, hot summer days. If you are willing to go through the extra effort for crunchy lettuce leaves, plant your lettuce in a cool spot on the north side of your garden, preferably with some shade and keep it well watered. Try heat loving Canasta, Jericho, or Mescher lettuce to keep your salad greens going strong throughout the season.

This is the perfect time to plant the Roselle Hibiscus tea plant. Planting now will ensure these stunning 4-6' tall plants have enough time to grow large and support a large harvest of deep red calyxes. Flowering begins at the fall equinox, when flowers will turn into seed pods (or calyxes) that you can harvest and dry for a year around supply of delicious hibiscus tea.

Don’t worry if you don’t have a lot of space, maybe you can’t grow corn, but you can put together a few 5-gallon sized containers and start some peppers and/or tomatoes with a sturdy trellis and have a houseplant that provides you with steady garden treats for your kitchen! You can also fill a pot with Koba green onions and bolt tolerant Leisure Cilantro for “cut and come again” to add an uplifting touch of garden green flavors to every meal.

Once you have ordered your garden seeds you can start preparing your garden beds for your selected crops. There are just about as many different ways to build a garden bed as there are seeds to plant. When deciding how to build your garden beds you want to first consider what type of soil you have.

There are a vast range of soil types in Hawaii from quick draining, young volcanic cinder soil to heavy, red dirt clay to sandy saline soils. My family farm is on the East Side of the Big Island, where we have a high organic matter “muck” type soil peppered with an abundance of blue rocks. This type of soil takes a lot of strong backs to dig and sift through, but once you pick out the rocks and fluff up the soil with digging forks there remains a beautiful dark living soil, high in sulfur and organic matter and low in phosphorus, calcium, magnesium and other macro minerals. We also see heavy rainfall, so staying up on regular feedings, adding nutrient rich finished compost and having a steady foliar tea schedule is a critical part of our success. The rain also brings soil compaction, which means we need to stay on top of cultivating our soil regularly to keep the soil loose, well drained and support healthy root systems.

Digging Your Beds

There are a few tools that I like to use to make the job of digging easier on my body. The first tool that I use is a pick-axe, using the thick side of the axe to scrape away grass from the surface of the soil. There is usually a healthy number of worms in this material, so be sure to add it to the compost pile! When digging into soil that hasn’t been worked in a while it is easier to go through the area and break up the soil first with a pick-axe or an o’o bar that will release the initial compaction of the soil. Once you have loosened the area try using a digging fork or a border fork to open the soil enough to start to pull out the rocks and the roots of weeds. This can also be done with a sharp spade or shovel. Once you pull out most of the rocks and loosen your soil you are ready to do some soil amending before you plant.

An Alternative to Digging

With early planning, you can simply cover the area you are planning to make into garden beds. Spreading a thick layer of cardboard, weed mat, old roofing material, tarps or heavy mulch on your planned garden area, and leaving your selected material for two to three months, will set back the grass and weeds enough to expose your soil and simplify the clearing process. By covering your garden area, rather than digging off the grasses and weeds, you maintain the benefit of the organic material, worms and soil structure right where your plants will go. This regenerative no-till method used by farmers and gardeners around the world is time and labor saving, but requires planning ahead. If you missed this step earlier in the year don't worry, you can always plan this for a fall garden and for now - gather your keiki and tools and dig up your lawn, at least you won't have to mow that patch of grass!

Of course there are areas in Hawai'i that are all rock and will require you to build above ground raised beds. Fortunately we have access to green waste and abundant bio-mass flourishing that can be shredded, chipped or laid down and covered to build soil and get growing!

I am an advocate of soil testing and believe without a soil test you will always be guessing!

At my family farm we use A&L Labs to get results that works well with organic methodology including fertilizer and mineral application rates. If you aren't experienced taking a soil sample click the link above to take you to a page that offers clear instructions, detailing how to gather soil for a quality sample and how to send your soil to be tested. Stay tuned for more information about reading soil samples in future blogs!

Amending garden beds is feeding the soil that is going to feed you, your family and friends.

All crops need nitrogen, phosphorus, and potassium for healthy growth. Knowing exactly how much in relation to what is already in your soil is where the soil test is so helpful! One of the things your soil test will tell you is the pH of your soil, which is very important in relation to how you add Calcium to your soil. The ideal pH soil range is between 6 and 7 for most garden crops. In Hawaii, we tend to have more acidic soils and so most gardeners can add calcium carbonate or dolomite (if Magnesium is low), but if you have an alkaline, high pH soil then gypsum is the best calcium source to use so that the calcium will not keep raising pH levels.

If you can’t get a soil sample or want to get planting before your test comes back, it’s okay - you can do that – just be sure to follow a few general rules of thumb:

  • When adding amendments to your soil think about adding salt to your food - sprinkle lightly!

  • Calcium and phosphorus are generally needed in abundance and have heavier application rates. Cal-Phos is a good addition that has been harder to get recently, but you can usually find calcium carbonate and a good bone meal to add to your soil. Be certain whether you need Magnesium in your soil before adding Dolomite!

  • Chicken manure and horse manure are great soil additions when planting long-term crops like corn, eggplant, squash, and peppers but don’t add these manures to garden beds that are being planted with lettuce or leafy greens.

  • Try to find a good organic pelleted general fertilizer that is not too expensive and easy to apply, they help to take the guesswork out of fertilizer application rates.

I like to add calcium, bonemeal and any manure to well forked beds and give them a good working in with my border fork deeper into the soil, about 12-15”. Then I shape the beds so that water permeation is easy and thorough and add fertilizer and finished compost to just the upper two inches of soil where the rain can bring those calories down into the soil slowly over time. Note my compost is “finished”, meaning it has matured and I don’t expect to find an abundance of weed seeds sprouting or any unwanted pathogens. Unfinished compost should not be added to beds, but rather left to finish and mature into a beautiful humus rich soil addition. Stay tuned...we will be digging deeper into compost building methods in upcoming blogs!

The way I see it we have to feed to soil to have it feed us – be prepared to add calcium, bone meal, potassium and trace minerals to feed and nourish the soil.

Let’s talk about minerals…to have successful growth and pollination it is critical for plants to have access to micronutrients either through the soil or through foliar applications. Calcium, Magnesium and Sulfur are as important as getting adequate NPK, but it’s also important to have enough Copper, Iron, Manganese, Boron, Zinc and Molybdenum to name a few. Most soils are mineral depleted and benefit from a foliar application of an organic fish and seaweed liquid fertilizer that you can purchase at your local garden center or online. Tips to remember when giving foliar applications:

  • Make sure plants are well watered and not at all thirsty.

  • End of day applications are best, early morning is okay too.

  • Gently and finely misting the undersides of leaves (where the stomata live) is the most effective application, but a simple soil and leaf drench works well too.

  • Staying up on regular weekly foliar applications will provide excellent results!

You can also use crop residue to make your own liquid fertilizer right in your yard. Here is a link to a fun page from the Farmer's Almanac with videos that describes how to brew your own garden tea for a foliar application soil drench.

With your beds dugs and amended they are fully prepped and ready to receive your treasured vegetable and flower starts. Remember to plant your starts deep into the soil (right up to the base of those first true leaves) and always give them a good drink of water immediately after planting for best success.

Stay tuned to future blogs from the Hawai’i Seed Growers Network to gather growing tips and learn about new varieties to try for your home garden.

Thank you for supporting Local Seeds for Local Needs, your source for locally adapted seed varieties.

Happy Growing!

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