Dioscorea Japonica: Yamaimo, Japanese Mountain Yam

One fascinating wild yam species is Dioscorea japonica, also called Yamaimo. It’s a Japanese wild yam with excessive worth in Japanese delicacies. Just like the Chinese language yam, it’s generally known as the Japanese cinnamon vine, distinguishing it from the Chinese language cinnamon vine. Their frequent names are sometimes used interchangeably. 

It stands out amongst different yam species as a result of it’s one of many few that’s eaten uncooked. It’s additionally cold-hardy, differentiating it from Chinese language yam, or cinnamon vine. They’re each members of the true yam Dioscoreaceae household, within the genus Dioscorea and so they each develop into a number of feet-long tubers. 

Yamaimo is native to the mountains of Japan however takes off in North America. Many of the issues individuals have with this glutinous yam is controlling it. Its Chinese language relative is an invasive species in sure elements of america, and in addition requires upkeep. However you possibly can develop yamaimo at dwelling.  

Fast Care Information

Dioscorea japonica is a captivating vining plant that produces edible tubers. Supply: harum.koh
Frequent Identify(s) Yamaimo, mountain yam, Japanese yam, East Asian mountain yam, Jinenjo, shan yao, nagaimo, cinnamon vine 
Scientific Identify Dioscorea japonica
Days to Harvest 730 days
Mild Full solar to partial shade
Water 1 inch per week
Soil Mild, wealthy, well-draining
Fertilizer Sluggish launch, pellet utilized after 8 weeks of progress
Pests Root knot nematodes, birds, mice
Ailments Root rot

All About Dioscorea Japonica

Air potatoes of Dioscorea japonica
The “air potatoes” or aerial tubers of Dioscorea japonica. Supply: shikigami2011

Yamaimo (Dioscorea japonica) is a Japanese yam native to Japan, Korea, China, Taiwan, and Assam. It’s generally known as mountain yam, Japanese yam, East Asian mountain yam, Jinenjo, shan yao, nagaimo, and Japanese cinnamon vine. In Korean it is called cham ma 참마 and dang ma 당마. It grows wild within the mountains of its native Japan, the place there’s a custom of rising each the Japanese yam and the Chinese language cinnamon vine. There, Dioscorea japonica is named Yamaimo – actually Japanese yam. 

Probably the most hanging a part of Yamaimo is its lengthy white tuber. Normally buried 1 to three toes underground, they attain 1 to three toes lengthy. They’re speckled with a tan to whitish pores and skin. A single perennial climbing vine grows from every wild yam that reaches 10 toes tall. The vine’s leaves are elongated and appear to be different heart-shaped candy potato leaves. 

Yamaimo is dioecious and requires cross-pollination for the replica of seeds. Feminine crops produce small string-like white or yellow flower bunches in late summer season that resemble oak pollen and scent like cinnamon. Male crops develop small tubers above floor on the leaf axils of the vine, generally known as air potatoes. Most present in North America are male Dioscorea japonica crops. 

Yamaimo edible elements embrace the tuber, and air potatoes (or seed), however the tuber requires some processing earlier than they are often consumed. The air potatoes will be roasted and snacked on like edamame. The air tuber and tuberous root have a impartial taste that always acts as a binder for numerous meals – like soba noodles, as an illustration. 

The meals chem of the yam is most fascinating. When eaten uncooked, they’re both shredded or grated to take away the fibrous, indigestible elements. Those that deal with the uncooked tubers put on gloves as a result of they irritate the pores and skin. They’re blended with different flavorings, and style a bit like a potato. However their texture is different relying on the preparation. 

They’re utilized in candy confections for binding, and typically they’re cooked right into a tender, sticky, and crunchy pancake. They’re generally made into dumplings thrown into miso soup, and the slippery texture or slimy texture of grated Yamaimo is superb in noodle dishes of all types. 

Yamaimo is medicinal in China and it’s thought of wild mountain medication in Japan the place it’s used to deal with digestive issues, and to help kidney functioning. Like different wild yam species, it regulates hormones and is usually used as contraception. In phyto-chemistry Dioscorea japonica is taken into account antioxidant and anti inflammatory. Within the Edo Interval in Japan sliced yamaimo was added to baths to advertise virility. 

Present research spearheaded by Sei-Ichi Nakamura point out dang ma 당마 (or cham ma 참마) has antimutagenic capabilities by way of alcohol compounds contained within the plant’s chemistry. Dioscorea japonica to Sei-Ichi Nakamura and associates exhibits promise within the suppression of most cancers. 

There are 4 accepted formal botanical styles of Yamaimo (Dioscorea japonica) – which interprets in English to Japanese yam. A number of formal botanical varieties are virtually equivalent. They’re as follows:

  • In Japan, Korea, Ryukyu, Bonin, Anhui, Fujian, Guangdong, Guangxi, Guizhou, Hubei, Hunan, Jiangsu, Jiangxi, Sichuan, Zhejiang, and Taiwan: Dioscorea japonica var. japonica
  • In Assam: Dioscorea japonica var. nagarum
  • In Guangdong, Guangxi, and Taiwan: Dioscorea japonica var. oldhamii
  • In Anhui, Fujian, Guangxi, Guizhou, Hubei, Hunan, Jiangsu, Jiangxi, and Zhejiang: Dioscorea japonica var. pilifera

Planting Yamaimo

Plant every tuber in late spring. Put together a sight with mild, wealthy, well-draining media, and plant it at the very least 1 foot deep. 3 toes is greatest. As a result of the wild yam of Yamaimo is fragile and may break through the harvest growers plant it in a plastic tube in a raised mattress, or a barrel of some type. The realm you plant it in ought to obtain full solar or partial shade. When you’ve chosen and ready the planting web site, plant the tuber, and inside a month or so that you’ll have new shoots within the type of seedlings. Sprouted Yamaimo air potatoes will be planted in the identical method. If spring is already previous, take into account planting rooted stem cuttings in summer season. We’ll talk about extra of the ins and outs of propagating Japanese yam later on this piece. 

While you plant your Dioscorea japonica, present a sturdy trellis to help its upward progress. This could possibly be alongside a chain-link fence, or by way of a wood trellis you’ve constructed. At first, a single pole will suffice, however because the vine grows present extra help. Contemplate this deciding on your planting web site. 


Back side of Dioscorea japonica leaf
The again facet of a Dioscorea japonica var. japonica leaf. Supply: Shihchuan

After you have a longtime Dioscorea japonica vine, you’re in your strategy to harvesting a Japanese mountain yam. As a result of the tuber of Yamaimo takes some time to develop, you’ll have time to give attention to caring for the vine. 

Solar and Temperature

Dioscorea japonica wants full solar to partial shade. Give it at the very least 6 hours of daylight per day. This cold-hardy Japanese yam can face up to chilly right down to -25 levels Fahrenheit and warmth as much as 100 levels. Within the winter, Dioscorea japonica will die again, however the tuber will proceed to develop protected within the heat earth. When you’ve got notably chilly winters, burying the yam deeper will assist shield it from the frozen floor.  

Water and Humidity

The Japanese yam Dioscorea japonica wants constantly moist soil to thrive. Water the plant day by day within the morning, making certain the highest two inches are moist, however not waterlogged. A minimum of 1 inch of water per week is greatest. Within the warmth of summer season, water a bit extra to help satisfactory tuber progress. Yamaimo doesn’t want added water in areas and seasons when it rains typically. Soaker hoses and drip irrigation are one of the best modes of watering the East Asian mountain yam, however a constant and sluggish trickle from a hose or watering can work simply as properly, so long as the medium is well-draining and doesn’t get too moist. Yamaimo just isn’t drought tolerant. 


Mild, wealthy soil is greatest for Dioscorea japonica. In case your media base is heavy clay soil, domesticate this wild mountain medication in a big container. Should you’d wish to develop it within the floor, plant Yamaimo deeply, as much as three toes. A light-weight loamy soil that’s impartial to mildly alkaline is greatest. Good drainage is crucial as a result of a scarcity creates circumstances the place ailments can proliferate. The pH vary for rising Dioscorea japonica is 6.1 to 7.8. Use small quantities of backyard lime in case your soil is just too acidic. This glutinous yam wants moist soil, so present some coco coir or sphagnum peat moss in case your soil has a tough time holding moisture. 


Fertilize your Zhejiang Dioscorea japonica var. japonica or your Dioscorea japonica var. of one other type after 4 weeks of progress, in early summer season. Use slow-release pellet fertilizers which might be full-spectrum, at 10-10-10 or 20-20-20. Should you do fertilize later within the season, use a 10-20-20 fertilizer which accommodates the phosphorous and potassium content material that can assist you produce giant tubers. 


Prune your Dioscorea japonica var. to regulate its unfold. Trim elements to coach the vine’s form as properly. As a result of the small air potatoes produced on male vines and their clones can drop to the bottom and propagate, take time to take away these in order that they don’t take over.  

One other applicable time to prune is on the finish of the rising season within the fall. Take away all of the leaves after they’ve browned, and depart a small 5-inch stem on the base. Mulch to guard it from the chilly. 


Propagate any Dioscorea japonica var. from cuttings in early to late summer season, relying on the place you reside. These in temperate zones ought to plant cuttings in early summer season, after rooting them in water in spring. It’s going to take at the very least two years for a considerable tuber to type, which can must be excavated and transplanted extra deeply after a couple of months of progress. 

Yamaimo is propagated is by the division of a full-grown tuber, or by seed, which comes from the edible air potato. The latter of those is the commonest type of propagation in Japan. While you harvest the bulbs, lay them in a field within the shade in a heat, darkish place. They are going to sprout on their very own this fashion. Then kind out every seed that’s irregularly fashioned, and discard them. Take the remainder of the edible bulbs and plant them a few inches within the floor, making certain the seed sprout just isn’t damaged within the course of. In about 5 weeks you’ll have seedlings you possibly can switch to your most popular space for progress. 

To divide this edible native Japanese tuber, look forward to the crops’ dormant season in winter. Rigorously take away the tuber and minimize it into applicable elements with sufficient pores and skin for satisfactory sprouts to type. Then plant the tuber elements deeply in late spring in mildly alkaline soils which might be mild and wealthy. Prepare them onto a trellis. 

Harvesting and Storing

Yamaimo and ayu (sweetfish)
Yamaimo with a small piece of ayu (sweetfish). Supply: mmmyoso

The perfect a part of spending years rising yams within the Dioscorea genus is harvesting the tuber. It’s delicate, so take some care on this course of. 


Like different members of the Dioscorea genus, harvest your Yamaimo within the fall after two years of progress from a seedling. Should you’ve ready a plastic tub or tall planter to develop this Japanese and Korean native, merely tip over the bin and slowly excavate the tuber, taking care to not break it within the course of. Native Dioscorea japonica growers typically plant them within the grime in plastic sleeves, making it simpler to take them out of the earth with out breaking them. Don’t wash the Yamaimo tuber till you’re prepared to make use of it. 

Harvest the tiny air tuber from Yamaimo all through its progress interval. Kind these, saving the irregular ones for consuming, and the extra uniform ones for propagation. 


The tuber retains for 1 month saved in a cool dry place, unwashed and wrapped in newspaper. Should you don’t have a cool dry place in your own home, attempt the fridge for a few days. Cooked Yamaimo retains in an hermetic container within the fridge for two to three days. Powdered types of the yam maintain for 1 yr in an hermetic package deal or container at room temp. In grated type, the Yamaimo retains within the freezer and used as wanted inside 2 weeks. Some sources slice the yam and dry it, storing it at room temperature in a mason jar, although it’s unclear how lengthy it may be stored this fashion. 


Japanese yam tubers
Small tubers from Dioscorea japonica. Supply: UnconventionalEmma

With Yamaimo, you received’t encounter many points, aside from making certain it has an excellent rising medium and doesn’t get out of hand. Let’s discuss a few belongings you’ll wish to look out for. 

Rising Issues

Give Japanese yams mild, wealthy, well-draining soil. Should you plant your tuber within the earth in an space with heavy clay soil, you’ll stunt its progress and create circumstances the place illness can happen. Because the air potatoes develop and drop to the bottom, choose them up. In any other case, you’ll be eradicating suckers the next spring. 

Trellis your Yamaimo adequately so it has good help. This help offers room in your air potatoes to develop and offers your tuber extra entry to solar and water. While you’re harvesting the tuber, attempt to not break it. Present it with a plastic tube, or sleeve, or plant it in a raised mattress that may have a wall eliminated whilst you harvest. Damaged yams won’t final so long as intact ones. 


Root-knot nematodes are the worst pest for this yam. These small white to yellow worms drill into tubers and lay eggs there. Whereas they feed, they create nodules on every tuber, distorting the molecular and chemical composition of your harvest. As a result of it takes time to develop a tuber, stop nematodes with a helpful nematode species. Apply these diluted in water to the planting space when soil temperatures are between 42 and 95 levels. Then comply with up with a second software one to 2 weeks later. This ensures knot nematodes aren’t current whenever you plant your tuber.  

Birds and mice will feed in your air potatoes in case you’re not cautious. Whereas this shouldn’t be a difficulty at a sure level if you wish to save them, attempt an owl decoy to maintain birds away. Nevertheless, mice and birds could help you in conserving the vine below management. 


In poorly draining soils, root rot will be a difficulty. The issue with this illness is you received’t comprehend it’s there till harvest. Yamaimo will tackle giant discolored splotches that trigger elements of it to go dangerous earlier than you possibly can take pleasure in it. Late levels of the illness typically present themselves in storage because the discoloration progresses to a moldy spot. Don’t plant your tuber the place you already know root rot has existed. Present a medium that’s mild, wealthy, and well-draining. Should you’re uncertain concerning the planting space, plant your tuber in a deep barrel of some type. There isn’t a treatment for this illness. In case your tuber will get contaminated, propagate an air potato and begin once more. 

Regularly Requested Questions

Yamaimo leaves
Younger yamaimo leaves earlier than they’ve totally widened out. Supply: plj.johnny

Q: Is Chinese language yam the identical as Japanese yam?

A: Each the Japanese yam and Chinese language crops produce a glutinous yam that’s used interchangeably. They do share the identical genus, however what differs between them is their species and their hardiness. Chinese language yams develop in hotter climates, whereas the formal botanical styles of Japanese yam have exhibited chilly hardiness. 

Q: How do you eat yamaimo?

A: In Japanese delicacies, it’s grated and made right into a paste that may be fashioned into dumplings for soup. It’s additionally sliced, wrapped in bacon, battered, and deep-fried. It has candy purposes as properly! As a result of there are a number of formal botanical varieties native in Taiwan, Japan, China, and Korean meals chem, there are a lot of purposes for these crops. One acquainted use for the crops is to enhance the feel of noodles.

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