What are Okayama’s heirloom vegetables? Features, season, and ways to eat the 12 varieties (including GI Tsurajima burdock and Bizen black-skin kabocha) explained

Okayama Prefecture's heirloom vegetables are varieties handed down amid diverse terrain, such as the warm climate of the Seto Inland Sea coast, the Kibi Plateau and the Chugoku Mountains, the sandy loam of the Kurashiki and Okayama plains, and the reclaimed land of Kojima Bay.The Japan Traditional Vegetable Promotion Associationorganizes Okayama Prefecture's 12 regional items (as of September 2023); this article explains 10 vegetable items in the main text and covers the more fruit-leaning kuro suika and Mohei uri in the "other local specialty varieties" section at the end.

Tsurajima, registered as GI No. 24 in December 2016burdock, the burdocks Ashimori gobo, Hisashi gobo, and Meiji gonbo, the silk-thin-skinned Koromogawa nasu, Setouchi City's Bizen kurokawa kabocha (2024 GI No. 143), Omachi seri continuing from the Edo period, Bizen City Tsurumi's Tsurumi nasu, Mimasaka's Manzen kabura, Maniwa's Doibun kona, and other native varieties of Bizen, Bicchu, and Mimasaka are introduced.

The definition of "heirloom vegetable" and the scope of this article

There is no nationwide unified definition of “heirloom vegetables,” and criteria differ by certifying body. We lay out the criteria of the main certifying bodies.

Certifying body	Main criteria
Kyoto Prefecture "Kyoto Heirloom Vegetables"	Has a cultivation history from before Meiji and covers the whole prefecture (includes bamboo shoots, excludes mushrooms and ferns, and includes extinct items)
Osaka Prefecture "Naniwa Heirloom Vegetables"	Cultivated within Osaka Prefecture from roughly 100 or more years ago
Nara Prefecture "Yamato Heirloom Vegetables"	Production in this prefecture confirmed from before the war; distinctive cultivation method, flavor and aroma, form, and provenance characteristics
Nagano Prefecture "Shinshu Heirloom Vegetable Certification System"	Provenance, food culture, variety traits (provenance from before the 1955-1965 period)
Okayama Prefecture	No prefecture-specific heirloom vegetable certification system. JA Hare-no-Kuni Okayama and each municipality support regional branding

This article covers 10 vegetable items in the main text out of the 12 Okayama items organized by the Japan Traditional Vegetables Promotion Association, and separately introduces kuro suika (watermelon) and Mohei uri (makuwa melon) in the "other local specialty varieties" section at the end.

What are Okayama's heirloom vegetables? The food culture of Bizen, Bicchu, and Mimasaka

Area	Representative items	Regional characteristics
Bizen (Okayama City, Setouchi, Bizen)	Ashimori gobo, Omachi seri, Tsurumi nasu, Bizen kurokawa kabocha, kuro suika	The center of the Seto Inland Sea coast and the Okayama Plain
Bicchu (Kurashiki, Ibara, Kasaoka, Takahashi)	Tsurajima gobo, Koromogawa nasu, Meiji gonbo, Mohei uri	The Takahashi River basin and the Kurashiki and Kojima areas
Mimasaka (Tsuyama, Maniwa, Mimasaka City)	Hisashi gobo, Doibun kona, Manzen kabura	The southern foot of the Chugoku Mountains and the Kibi Plateau

Led by four burdock items (Ashimori, Tsurajima, Hisashi, Meiji), it lines up eggplant, turnip, leafy vegetables, and gourds. From the Bizen coast to the Mimasaka mountains, the item composition differs by terrain.

Historical background: sandy-loam burdock-producing regions and traditional pickles

• Tsurajima gobo — Full-scale cultivation began around the late 1940s in the Tsurajima area of Kurashiki City, and it was registered as GI No. 24 of the Ministry of Agriculture, Forestry and Fisheries on December 7, 2016
• Omachi seri — Open-field water dropwort from the Takashima district of Naka Ward, Okayama City. A native item cultivated continuously since the Edo period, now rare with about two producers
• Manzen kabura — A turnip with a red-purple neck from the Manzen district of Mimasaka City. A variety suited to pickles
• Bizen kurokawa kabocha (Bizen black-skinned pumpkin) — A black-skinned pumpkin cultivated in places like Ushimado Town, Setouchi City. Registered as GI No. 143 of the Ministry of Agriculture, Forestry and Fisheries on January 29, 2024

A list of Okayama's 10 main heirloom vegetables and a seasonal calendar

Four burdock items

Item	Features	Growing region	Season
Tsurajima gobo	Fair-skinned, soft, and sweet (GI No. 24)	Kurashiki City (Tsurajima, Mizushima, Nishiachi, Odaka areas)	Grown three times a year, shipped year-round
Ashimori gobo	Thick and short, white, soft flesh	Fukutani, Kita Ward, Okayama City	August to February
Hisashi gobo	Soft, dense flesh	Hisashi, Mimasaka City	Late September to December
Meiji gonbo	Thick, fine-fibered, strongly sweet	Udogawa and Meiji, Yoshii Town, Ibara City	Late August to late March

Eggplants, turnips, pumpkin

Item	Features	Growing region	Season
Koromogawa nasu	The thin-, soft-skinned "silk eggplant"	Kojima and Hayashi, Kurashiki City	June to October (peak in August)
Tsurumi nasu	Late-maturing, red-purple, few seeds	Tsurumi, Bizen City	Early July to mid-October
Manzen kabura	Red-purple neck, curved root, for pickles	Manzen, Mimasaka City	November–December
Bizen kurokawa kabocha / Bizen black-skinned pumpkin (GI No. 143)	Deep black-green skin, viscous, sticky-textured flesh	Setouchi City, Okayama Prefecture	Harvested July to August, shipped December to the following June after long-term storage

Leafy greens

Item	Features	Growing region	Season
Omachi seri	Open-field from the Edo period, now two producers	Takashima, Naka Ward, Okayama City	Late December to March (peak January to February)
Doibun kona	Ten stalks emerge from one plant, with pungency and slight bitterness	Kurogui, Maniwa City	Mid-October to March

The characteristics and ways to eat seven representative Okayama heirloom vegetables

Of the 10 items, considering the GI registration status and the weight of association listing, we take up seven representative items.

Tsurajima gobo — the branded burdock of GI No. 24

Season	Grown three times a year and shipped year-round
Growing region	Tsurajima area, Mizushima area, Nishiachi, and Odaka of Kurashiki City
Well-suited dishes	Kinpira, simmered dishes, tempura, salad

Tsurajima gobo is a native burdock whose full-scale cultivation began around the late 1940s in the Tsurajima area of Kurashiki City, and it was registered as Geographical Indication (GI) No. 24 of the Ministry of Agriculture, Forestry and Fisheries on December 7, 2016. With cultivation in well-draining sandy loam based on soil diagnosis, it achieves a white skin of even length and a flavor that is soft, sweet, and leaves no fiber in the mouth.

It grows quickly, and forcing cultivation allows three plantings a year, so year-round shipping is also a characteristic. Its flavor stands out in kinpira, simmered dishes, and tempura. Distributed nationwide with a GI mark, it forms one of western Japan's leading burdock-producing regions.

Ashimori gobo — Okayama City's thick, short, fair-skinned burdock

Season	August to February
Growing region	Fukutani district, Kita Ward, Okayama City
Well-suited dishes	Simmered dishes, kinpira, tempura, burdock dishes

Ashimori gobo is a native burdock cultivated in the Fukutani district of Kita Ward, Okayama City, with a stubby shape thicker and shorter than common burdock and a white, soft flesh as its signature. The Ashimori area lies on the north side of Kibi no Nakayama, and the sandy loam and foothill climate suit burdock cultivation.

Cut into rounds and simmered, its texture comes alive, and you can enjoy its softness in kinpira and tempura too. In its August-to-February season, it is shipped at JA farm stands within Okayama City.

Koromogawa nasu — the thin-skinned "silk eggplant"

Season	June to October (peak in August)
Growing region	Kojima and Hayashi districts, Kurashiki City
Well-suited dishes	Grilled eggplant, agebitashi, light pickles, salad

Koromogawa nasu is a native eggplant cultivated in the Kojima and Hayashi districts of Kurashiki City, also called "silk eggplant" for its thin, soft skin. Owing to the thin skin, it is a soft-textured variety also used in light pickles and salads.

Made into grilled eggplant or agebitashi, you can enjoy a melting texture that makes the most of its thin skin. In its June-to-October season, especially the August peak, it is shipped at farm stands in the Kojima district of Kurashiki City.

Bizen kurokawa kabocha — the sticky black-skinned pumpkin of Setouchi

Shipping period	December to the following June (harvested July to August, long-storage type)
Growing region	Setouchi City, Okayama Prefecture (GI-registered region)
Well-suited dishes	Simmered dishes, soup, potage, tempura

Bizen kurokawa kabocha (Bizen black-skinned pumpkin) is a black-skinned pumpkin cultivated in Setouchi City, Okayama Prefecture, a Japanese-pumpkin lineage characterized by deep black-green skin and viscous, sticky flesh. It is harvested in summer (July to August), but has high storability and is shipped over a long period from December to the following June while being after-ripened in a cool, dark place. On January 29, 2024, it was registered as GI No. 143 under "Bizen kurokawa kabocha / Bizen black-skinned pumpkin" (registering body: Bizen Kurokawa Kabocha Promotion Council).

Made into simmered dishes, its viscous, sticky texture stands out, and made into soup or potage, it finishes with a smooth mouthfeel. In tempura, you can enjoy the flesh's richness.

Omachi seri — Okayama's open-field water dropwort continuing from the Edo period

Season	Late December to March (peak January to February)
Growing region	Takashima district, Naka Ward, Okayama City
Well-suited dishes	Seri hot pot, ohitashi, aemono, tempura

Omachi seri is an open-field water dropwort cultivated continuously since the Edo period in the Takashima district of Naka Ward, Okayama City, and according to the Japan Traditional Vegetables Promotion Association (as of September 2023), producers have declined to about two households. An open-field crop eaten down to the root, it is characterized by strong aroma.

Made into seri hot pot, you can enjoy it whole from root to leaf, and its aroma stands out in ohitashi, aemono, and tempura too. In the January-to-February peak, it circulates in limited amounts at farm stands within Okayama City.

Manzen kabura — Mimasaka's red-purple-necked turnip

Season	November–December
Growing region	Manzen, Mimasaka City
Well-suited dishes	Pickles, vinegar pickling, simmered dishes

Manzen kabura is a native turnip cultivated in the Manzen district of Mimasaka City, characterized by a distinctive shape with a red-purple neck and a root that curves like an ox horn. Its flesh suits pickles, and its crimson coloring comes alive in vinegar and salt pickling.

In its November-to-December season, it is shipped at JA farm stands within Mimasaka City and used as a regional winter pickle ingredient.

Meiji gonbo — Ibara City's strongly sweet thick burdock

Season	Late August to late March
Growing region	Udogawa and Meiji districts, Yoshii Town, Ibara City
Well-suited dishes	Kinpira, simmered dishes, tempura, burdock steak

Meiji gonbo is a thick burdock cultivated in the Udogawa and Meiji districts of Yoshii Town, Ibara City, with fine fiber and strong sweetness as its signature. A native variety handed down in the mountainous part of Ibara City, per JA Hare-no-Kuni Okayama's information it is shipped from late August to late March.

Its sweetness stands out in kinpira and simmered dishes, and it also suits dishes that enjoy the ingredient's flavor, like burdock steak. It is shipped at JA farm stands within Ibara City.

How to buy Okayama's heirloom vegetables and tips for storage

Item	Main sources	Timing
Tsurajima gobo	JA Hare-no-Kuni Okayama, farm stands within Kurashiki City, nationwide mail order (with GI)	Year-round
Ashimori gobo	JA farm stands within Okayama City	August to February
Hisashi gobo	JA farm stands within Mimasaka City	Late September to December
Meiji gonbo	JA farm stands within Ibara City	Late August to late March
Koromogawa nasu	Farm stands in the Kojima district of Kurashiki City	June to October
Bizen kurokawa kabocha	Farm stands within Setouchi City (storage type)	Shipped December to the following June
Omachi seri	Farm stands within Okayama City	Late December to March
Manzen kabura	JA farm stands in Mimasaka City	November–December

Mail order / hometown tax to outside the prefecture

• Tsurajima gobo — Shipped year-round as a furusato nozei gift item of Kurashiki City. With a GI mark
• Ashimori gobo — Shipped in autumn and winter as a furusato nozei gift item of Okayama City
• Bizen kurokawa kabocha — Shipped in winter to spring via Setouchi City's furusato nozei
• Processed products — Kurashiki burdock crackers, processed Omachi seri products, Manzen kabura pickles, and others circulate

Efforts to protect Okayama's heirloom vegetables

Efforts	Details
Tsurajima gobo GI registration	Registered as GI No. 24 on December 7, 2016
Bizen kurokawa kabocha GI registration	Registered as GI No. 143 on January 29, 2024 (registering body: Bizen Kurokawa Kabocha Promotion Council)
The regional development of JA Hare-no-Kuni Okayama and JA Kurashiki Kasaya	Brand management and regional marketing of Tsurajima gobo
Support for carrying on Omachi seri	Okayama City supports carrying on the production of open-field water dropwort from the Edo period
Branding by each regional JA	Actively promoting Ashimori gobo, Meiji gonbo, Bizen kurokawa kabocha, and others as regional products

FAQ

Other regional specialty varieties

They are included in the Japan Traditional Vegetables Promotion Association's list, but we separately introduce items classified as fruit-like vegetables such as watermelon and gourds.

Item	Category	Growing region	Features
Kuro suika	Watermelon (fruit-like vegetable)	Senju, Ushimado Town, Setouchi City	A native watermelon with no stripes and deep-green to black-green skin, an oval shape, and red flesh
Mohei uri	Makuwa melon (fruit-like vegetable)	Mohei, Kasaoka City	A white makuwa melon with good aroma and strong sweetness. In season July to September

Summary

Okayama's heirloom vegetables number 12 varieties, including two GI items: Tsurajima gobo (GI No. 24, 2016) and Bizen kurokawa kabocha (GI No. 143, 2024). The composition adds two fruit-leaning items, kuro suika and Mohei uri, to 10 vegetable items consisting of four burdock items and Koromogawa nasu, Tsurumi nasu, Manzen kabura, Omachi seri, Doibun kona, and Bizen kurokawa kabocha, spreading across Bizen, Bicchu, and Mimasaka. It is a group of items handed down amid terrain such as the warm Seto Inland Sea climate, the sandy loam of the Kurashiki and Okayama plains, and the mountainous part of the Kibi Plateau.

In summer, Koromogawa nasu, Tsurumi nasu, and Mohei uri; in autumn and winter, the burdocks and Manzen kabura; and from winter to spring, Omachi seri, Doibun kona, and Bizen kurokawa kabocha, with Okayama-grown native varieties circulating by season. Through furusato nozei and farm stands, you can bring the ingredients of Bizen, Bicchu, and Mimasaka to the home table.

References / information sources

• Japan Traditional Vegetables Promotion Association, "Okayama Prefecture"
• Ministry of Agriculture, Forestry and Fisheries GI No. 24 "Tsurajima gobo"
• Ministry of Agriculture, Forestry and Fisheries GI No. 143 "Bizen kurokawa kabocha / Bizen black-skinned pumpkin"
• Bizen Kurokawa Kabocha Promotion Council
• JA Hare-no-Kuni Okayama "Tsurajima gobo"
• National Agriculture and Food Research Organization Genebank "Native Variety Database"

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