Saturday, June 26, 2010

Growing Winter Squash in Kihei

(Sweet Kikuza)
Ready to harvest

Winter squash is fairly easy to grow in Kihei. Most heirloom varieties are adaptable to the hot summer sun and 90 degree temps. Powdery mildew is ever present in the air here and it affects many vegetables. Most winter squash are hardy enough to withstand the negative affects and still produce at least 1 mature squash.

Growing a winter squash in a Smart Pot

I have acidic clay soil that's great for growing bananas but not for growing most vegetables. I double dug and amended a bed in my yard but normal veggies didn't grow very well in it. Then I discovered SmartPots. I've been able to grow all of my squash in 15 gallon Smart Pots filled with an organic potting soil. It doesn't take long before worms begin living in the potting soil and the soil gets even better over time.

Before I direct sow the seeds, I amend the potting soil with green sand and an organic or natural all-purpose fertilizer. Then I add additional fertilizer after 1 month and continue to add fertilizer at a minimum of 1 month intervals until the plant starts to die back.

Protected from melon fruit flies

The melon fruit flies and pickleworms have been the greatest challenge to growing melons, summer and winter squash in Kihei. Mosaic virus has also been a challenge that surfaces during the summer months.

As soon as the female flower closes, I cover it with a paper lunch bag. When the fruit begins to grow, I replace the paper bag with a fabric shopping bag and keep the squash covered until it's close to maturity.

Most winter squash develop thicker skins as they grow. After they thicken, the melon fruit fly larvae and pickleworms tend to be less successful in penetrating beyond the skin and into the fruit or stems. If you miss covering them right away and the melon flies attack the fruit the holes will be microscopic. As the fruit grows the holes become visible. Pickleworms bore large, very noticeable holes into the stems and vines. Wilted vines are sometimes evidence of pickle worm activity.

The melon fruit flies attacked the stem of this Kikuza but the vine and fruit survived and continued to grow to maturity.

Unless it's obvious that the fruit has been damaged, if you notice small holes give the squash more time before you cut it from the vine. If the larvae have been unsuccessful at penetrating into the fruit, the holes will dry and the squash will continue to grow. If larvae have penetrated into the fruit, it will eventually begin to rot.

I've found that January and February are ideal planting months for squash as the melon fruit fly mating seems to be inactive until late April and pickleworms aren't normally at infestational levels until June. By the end of April, I have to keep all the young squash covered and cover the pollinated females as soon as the flowers close. Sometimes the melon fruit flies will attack the females before the flowers open.

There are lures for the male melon fruit flies and a bait for the females - they do help but they haven't eliminated the problem. The lures and bait are available from the Univ. of Hawaii College of Tropical Agriculture, Cooperative Extension Office in Kahului (808) 244-3242. They offer a free 2 hour education program about fruit flies. Fruit fly bait and lures can also be purchased from Crop Production Services in Kahului.

More information about fruit fly infestation in Hawaii can be found here:

Fruit fly larvae look like maggots and can be seen in photos on the first linked website. Information about pickleworms and mosaic virus can be found in the Growing Tips - Pests & Diseases section on my side bar.

I've trialed many different varieties of winter squash and I'll continue to trial different seeds as well as experiment with earlier and later planting dates.

Greek Sweet Red was the variety I chose to trial for late summer planting. Seeds were planted in August and September with good results. Although I did find a few pickleworms in late September and early October, the damage was minimal. 

I've been able to grow winter squash successfully from seed when planted from late January through September. I haven't tried planting earlier or later but other gardeners on Maui tell me squash can be grown all year.
(Good taste of the oven)
Buen Gusto is so far the only variety I've planted that was too big and aggressive to grow in a 15 gallon Smart Pot. I planted it in a garden bed and it grew fairly well.

Seeds for all of the squash in this post are available from

- a blog post highlighting the tastiest winter squash from my 2010 garden.
In American cuisine, squash and pumpkins are most commonly used at Thanksgiving. But squash is a popular year round vegetable in European and Southeast Asian cuisines. Following are links to recipes, with detailed instructions, that feature squash. Butternut is the most common winter squash available from the market but any sweet winter squash can be substituted in these recipes.


  1. Great post Jane! i see that i will need to make a little more effort if i want a squash harvest.
    Have you had any trouble with the melon flies stinging the vines? How did you decide on March as the first planting date?
    Last year i planted Kabocha around the autumn equinox. The vines produced OK but i failed to provide enough protection from the melon fly. i was planning to plant this year around the winter solstice so the fruits are ripening when the fly pressure is lower.

  2. Hi Julie! Kathy Oshiro's book notes Mar-Aug planting times for squash. I have an article on growing Kobacha in Kona and it says the best time to plant is in Aug/Sept. Last year I experimented with Aug/Sept planting times and I didn't get any squash as there was a significant drop in flower production - especially male flowers. I didn't plant Kobacha and maybe Kobacha is different.

    So far my best results have been from Mar-June planting times. March has yielded the best results of all. Next year I want to try planting in Feb. January might work too.

    I haven't noticed melon fly damage to the vines but that doesn't mean there isn't any. There have been small holes in many of the stems. The lures work but the GF120 doesn't seem to attract anything. I've never seen any flies spazing under the banana leaves where I spray it.

  3. Beautiful squashes and thanks for the tips on protecting the fruit.
    I have lots of flies at my melon patch, they don't stay still long enough for me to take a good look, I couldn't ID them.

  4. Hi Mac! There are 4 destructive fruit flies - the Med fly is the most well known. The melon fruit fly is found at sea level to 1500 ft elevations but med fly and oriental fruit fly go up to 4000 ft elevations. They're a medium size fly but I can't ID them either when they're hanging around in my garden as they move too fast. I can tell the difference when they're caught in one of the lure traps.

  5. Aloha, Jane,
    I found your blog while reading Julie's "Dirty Fingernails 808". Wow, You have quite a garden! I will be moving to Upcountry Maui sometime next year. We have a tiny garden with 9 4x4 ft squares, which I try to do a wacky succession planting each time I'm "home", and my wife keeps it going until I get another trip every 4 months or so. Yes, I must start my own blog, and I will, but in the meantime, I'm learning a lot from yours and Julie's. Great blogs!
    A hui hou.

  6. Hi Pomaika'i! Mahalo for checking out my blog and for your compliments! That's great that you have 9 square foot garden beds in Upcountry Maui! It's easier to grow a garden in the Upcountry climate and you can grow a lot in that amount of space. Let me know when you start your blog.

  7. Thank you for this information. I'm curious to know what types of bags you use to cover the fruit and where you obtain them. Is food-grade plastic required or advisable for such coverage? Do you tie the top of the bag, or do you leave it open or slit for ventilation?

    I'm salvaging what I can from a fruit-fly damaged crop of Blue Ballet heirloom winter squash (Seeds of Change) in Haiku. I want to continue to grow winter squash, yet I would prefer better results next time.

    Also, have you ever planted winter squash mid-September through December? If so, what were the results? Why is this time of year not advisable for planting winter squash in the lower elevations of Maui?

    Thanks for your assistance.


  8. Hi Chris! Right after the female flower closes I cover it with a white paper lunch bag that I buy at Walmart in the section where they sell ziploc and other bags. After the squash starts to grow I cover it with a sort of worn out Chico-Bag that I've purchased at Down to Earth or Mana Foods. They're made of a nylon type of fabric. I leave the squash covered until it out-grows the bag or the skin is really tough.

    I usually just crunch the end of the paper bag around the stem. That's been enough to stop the fruit flies but pickleworms can crawl down the stem and into the bag. When the pickleworms are a problem I use a twist tie or clips to keep the bag as tightly closed as possible without damaging the stem.

    I've not planted squash past the 1st week of September so I don't know if they'll grow very well in the fall. The earliest I've planted melons/squash/zucchini was January 20th and they grew really well.

    The lures really do help a lot. The U of H in Kahului (I noted their number in the post) offers a short class about fruit flies and teaches you how to make a bait/lure trap. If they don't have the lures for sale you can purchase them at Crop Production Services in Kahului.

  9. Thank you so much for responding to my post. I will try bagging the fruits during my next crop of winter squash.

    Thanks for the links as well. I called the university and there is a fruit fly class in late August that I will likely attend. The links you shared have provided me with numerous other preventive ideas as well.

    Perhaps I will try some of the Baker Creek offerings. They have an incredibly diverse collection of winter squash.

    Have a great rest of your summer. Thanks again.


  10. Aloha Jane,

    Your blog is one of the best I've seen on any topic, inspiring me to post my first comment ever: the fruit fly attractant can also be purchased at Fukuda Seed Store here in Honolulu. Although I work at UH, across the street from CTAHR, it was easier to get it from Fukuda: 1287 Kalani St # 106 Honolulu, HI 96817
    (808) 841-6719.


  11. Hi Anonymous! Mahalo for you compliments! I appreciate your posting another source for the lures/bait as they're in high demand here during the spring and summer and CTAHR is often out of stock. They really do help to lower the population of melon and oriental fruit flies in my garden.

  12. Hi - i have a healthy looking kabocha vine producing many small fruit, but more an dmore they are rotting on the vine sometimes when they are only about a half inch. so far only one squash is maturing and is about 7 inches in diameter now. i have considered that it is too warm, water from the base and not the leaves, have fed it once during the growing season, sprayed leaves with milk/water for mildew, but the squash keep rotting on th evine. would appreciate any kokua!

    1. Where is your garden and at what elevation? What month did you plant the seeds? That's happened for me but during the hotter months, Some varieties of squash are not very heat tolerant. Also squash/melons/cucumbers in Hawaii are prone to powdery mildew. If the mildew starts early in the growth cycle of the plant you may not get any edible squash.