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Jerusalem Artichoke
Overview
- Jerusalem artichoke is a tuber crop native to North America.
- The crop is easy to grow in the Pacific Northwest and in almost all climates that do not have very hot summers.
- Tubers range in size from about two to ten inches and come in a variety of shapes.
- Yields can be very high for mature plants, reaching as much as eight pounds per plant.
- Tuber color is most commonly light brown or red/purple, occasionally white.
- Cooked tubers are firmer than potato and usually have a pretty neutral flavor.
- Tubers contain large amounts of the indigestible sugar inulin, which often causes gas and bloating.
- The plants produce tubers only when the day length is less than about 13 hours.
- The crop is propagated by planting tubers, although the plants are capable of producing true seeds that can be used to breed new varieties.
About Jerusalem Artichoke
Description
The Jerusalem artichoke, sunchoke, sunroot, or topinambur (Helianthus tuberosus) is a tuber forming member of the sunflower family. Its close relative, the woodland sunflower (Helianthus strumosus) is often lumped in under the same name due to its similar tubers and ability to hybridize with H. tuberosus. It is a distant relative of other sunflower family root crops like yacon and dahlias. The sunchoke has the distinction of being one of just a few food crops that were domesticated in North America.
Although there are multiple theories, we don’t really know where the name Jerusalem artichoke came from. The first English description of the plant in 1605 mentions a flavor of artichoke, so that is straightforward. The first known use of the term Jerusalem artichoke was in 1622. Although “Jerusalem” is sometimes said to be an anglicization of the Italian word girasole, that appears to conflict with the later adoption of the word to describe sunflowers in Italian. It is not likely that the plant was thought to have come from Jerusalem, because it was already widely and mistakenly believed in Europe that the plant came from Brazil. The French name, topinambour, referred to a Brazilian tribe. We’ll probably never know how the name originated, but it is no more troubling than the “Irish potato.” The shorter, “sunchoke,” is a name that appears to have largely taken over in English, being shorter, if not quite as charming. “Sunroot,” is perhaps a nicer sounding name, but it hasn’t made much progress since winning a contest for the new name of the crop in England in 1918.
I have a complicated relationship with this plant. I’m not sure if I love to hate it or hate to love it. I have grown it longer than any of the other tuber crops that I work with except potato and, when I aspired to start breeding plants, it was my first choice. There is only one problem: I have a digestive intolerance to inulin, the major storage carbohydrate in sunchokes. Because of this, I must limit my intake to no more than a couple of ounces per day. That was what made me interested in breeding this plant, but testing a lot of varieties to find out whether or not they make you sick turns out to be not much fun! This complicated relationship convinced me to drop this chapter when writing the Cultivariable Growing Guide, as I really wanted to focus on plants that I love to grow. I’ve since changed my mind, as I do love to grow sunchokes even if I don’t love to eat them. I’ll probably change my mind again in the future, as that is the nature of our relationship.
The structure of the sunchoke will be familiar to anyone who has grown a sunflower. The plants form one or more thick stems that branch to produce large leaves with a rough, sandpaper texture. Many varieties flower, producing familiar sunflower type blooms. Plants can grow up to 15 feet tall, and maybe taller. Most improved varieties are shorter than that, but height depends a great deal on climate and day length. Although naturally a plant of woodland edges that appreciates a good supply of water, Jerusalem artichoke will tolerate a wide range of conditions and can be grown in almost all of the United States and southern Candada, with the possible exception of desert areas. The resilience of the plant may be its most impressive feature, tolerating both heat and cold while yielding heavily even in poor soils. On top of this, it has no particularly serious pests or diseases. This sets it apart from virtually every other domesticated root crop.
The edible part is the cluster of tubers formed shallowly under the plant. The tubers are formed at the end of rhizomes and, although improved varieties tend to cluster fairly closely under the plant, wild varieties may produces tubers as much as four feet away from the center of the plant. The tubers have a mostly neutral flavor, but some varieties are slightly sweet or have a mild, nutty flavor. Yields can be quite large, commonly in the two to three pound range, reaching perhaps as much as eight pounds for tall varieties in rich soil.
Sunchoke is a perennial that grows new plants from the tubers produced in the previous growing season. It can survive very cold weather, so the plant will usually survive to complete its natural lifecycle and senesce late in the year.
Sunchoke is a polyploid, usually of tetraploid configuration, but also occasionally hexaploid. The level of ploidy does not appear to make a great deal of difference in agronomic characteristics.
There are perhaps twenty named varieties that are reasonably common in North America, although the full number of recognized varieties world-wide may be in the low hundreds. Although it is native to North America, there are more named varieties in Europe. However, it is well known that varieties go by many different names, particularly in Europe, and it is possible that what appears to be several hundred varieties may only represent a couple dozen genotypes. Jerusalem artichoke grows wild in the northern parts of the United States and Canada east of the Rocky Mountains.
History
Jerusalem artichoke was cultivated in North America before the arrival of Europeans, but the extent of this cultivation is, unfortunately, unknown. The crop probably spread from the watersheds surrounding the Ohio and Mississippi rivers as the result of human activity, but the exact center of origin in unknown. The range in which it grows wild is roughly a rectangle with the states of Arkansas, Georgia, Minnesota, and New York at the corners. The first written description of the Jerusalem artichoke was made by Samuel de Champlain in 1605. He writes “Doubling the cape (now Cape Code) we entered a cove, where there are quantities of vines, Brazilian peas, pumpkins, squashes, and some roots that are good, which the savages
cultivate, and which taste somewhat like chards.” He mentions later that the roots have the taste of artichoke. Shoemaker (1927) notes that sunchokes are no longer found in the area and that the soil does not seem well suited to them. This may be an indication that the natives were cultivating sunchokes received in trade from farther inland.
The native Americans of the northeast United States were agricultural, famously cultivating the three sisters: beans, corn, and squash. They also grew, and, to some unknown extent, domesticated other crops, some of which have sadly been almost totally lost. Most accounts describe the natives treating sunchokes as a mostly wild crop, at most introducing it and then allowing it to grow without the same kind of cultivation given to their other crops. This doesn’t seem surprising, since that is how people tend to grow it even today. The native Americans may have had the same kind of relationship with the plant that we do, waxing and waning each generation in various places, never making it to the rank of major crop.
Sunchokes were introduced to Europe only two years later, in 1607, probably by Marc Lescarbot, a companion of Champlain. It had become a fashionable crop in France within a decade and remained fairly popular in areas where the potato was not yet heavily cultivated. Multiple reports indicate that the variety first introduced to Europe had a red skinned tuber and it may be the same as the variety later named Ordinaire. Reading the early accounts of the sunchoke in Europe bears a distinct resemblance to reading the accounts today of anyone who grows the plant for the first time. They tend to begin with, “Wow, is this thing ever productive!” That is followed by, “We need to grow a lot more of this!” Finally, we have the stage of conspicuous silence.
Linnaeus gave the sunchoke its botanical name and mistakenly described its origin as Brazil. This resulted in the widespread idea that the sunchoke was introduced to North America as it had been to Europe, which persisted into the late 1800s.
The Jerusalem artichoke had a bumpy ride through the 20th century, with a number of short bursts of popularity both as a food and fuel crop. This reached a peak in the 1980s when the Jerusalem artichoke was marketed in a pyramid scheme that caused widespread financial losses in the Midwest. While it has been tried as animal feed and forage, feedstock for the production of alcohol and food additives, and even as human food, it has never really managed to find its niche and remains a minor crop. The small commercial crop has always been used almost entirely for animal feed, but it is not a particularly efficient feed since other mammals lack the ability to process the inulin, just as humans do. Its potential as a low maintenance garden vegetable seems to be attracting greater interest in the 21st century. Amusingly, reference works in English about the Jerusalem artichoke have been published about one per generation and each one seems to refer to the renewed or increasing interest in doing something with sunchokes. I suppose I am just taking my turn.
Nutrition
As with other sunflower family tubers, such as yacon and dahlia, Jerusalem artichokes primarily use carbohydrates that humans cannot digest for energy storage. Jerusalem artichoke tubers have roughly half the usable calories as the same amount of potato. This makes it a good choice for people who are watching their weight. Of course, if you have read our guides for other sunflower family crops, you probably can see the downside coming. One of the names for this crop that I didn’t mention in the introduction is “fartichoke.” Inulin cannot be digested by humans, but can be digested by bacteria that live in the large intestine. This works out fine for some people, with the only downside being a bit of gas. It works out less well for others. I am in the camp with John Goodyear, who wrote the following in 1863: “In my judgement, which way soever they be dressed and eaten, they stir up and cause a filthie loathsome stinking wind within the body, thereby causing the belly to be much pained and tormented[.]”
Some people who initially have trouble with Jerusalem artichokes can adjust to them by starting with small quantities and increasing their consumption slowly. Others, it seems, will never make the adjustment. Some research suggests that there may be an element of digestive intolerance with inulin in addition to the problems with fermentation in the large intestine. The best advice is to start slowly and keep portions small until you figure out how well you tolerate Jerusalem artichoke. The consequences of over-consumption for the intolerant can be very unpleasant.
Every part of the plant is edible, inasmuch as it is not toxic, but if you can find a use for sunchoke leaves or stems as a human food, you have unusual tastes. Perhaps the only part of any interest as an edible other than the tuber is the flower. The flowers smell a bit like chocolate, but have very little flavor. The seeds can presumably be pressed for oil, but if you want sunflower oil, you would be better off growing sunflowers. Jerusalem artichoke seeds are tiny in comparison.
Kaldy (1980) reported the following nutritional analysis:
| Protein | 6.53% DW |
| Fat | 7.33% DW |
| Sugar | 51.65% DW |
| Starch | 26.26% DW |
| Fiber | 5.28% DW |
| Vit A | 37 IU FW |
| Vit C | 0.82 mg/100g |
| K | 1.44% FW |
Cooking and Eating
Jerusalem artichoke tubers can be eaten raw or cooked. Like most root vegetables, they are versatile and can be substituted in dishes calling for potatoes, carrots, turnips, and many others. They are most commonly prepared by boiling or roasting. The thin skin can be left on or removed. Raw tubers will discolor when cut or peeled and left exposed to air, but this does not affect edibility.
There are several ways to reduce the inulin content in Jerusalem artichokes. Exposure to freezing temperatures causes the tubers to convert some of the inulin to fructose. This is consistent with the common practice of holding off to harvest and eat sunchokes in the spring, after they have wintered in the ground. This is probably more effective in cold climates than mild ones. I don’t find much difference between sunchokes harvested in fall or spring in our mild climate, where the ground rarely freezes. Another option is long, slow cooking. Long exposure to heat also converts inulin. Unfortunately, it takes a really long time. You probably need to cook sunchokes on low heat for at least 24 hours to convert most of the inulin. I will sometimes put them in a soup or stew in the winter and allow it to cook on the woodstove for a full day. The most efficient and reliable means to defuse sunchokes is lacto-fermentation (the same process by which sauerkraut is made from cabbage). This allows bacteria to convert the inulin outside of your body, so that the gas escapes harmlessly into the atmosphere instead of inflating your colon like a balloon.
Morphology
Height
Varieties range in height from about 18 inches to as much as 16 feet, with the majority of varieties between 6 and 10 feet tall. Sunchokes first form storage carbohydrate (inulin) in the stems and relocate it into tubers once the critical daylength is reached (generally in the fall). Because of this, the height of the plant is related to the maximum yield potential. The tallest varieties are able to house more carbohydrate in preparation for the onset of tuberization.
Cultivation
Climate Tolerance
One really nice thing about sunchokes is that they are native to North America. I enjoy exotic crops, but trying to grow them far from their homelands can be a chore. Jerusalem artichoke is a mildly domesticated, weedy plant with a wide climate tolerance. It will happily grow anywhere east of the Rockies and north of the 35th parallel, which is its native territory. It will also grow happily in the west, although you will need to make sure that it gets enough water. Sunchokes are pretty resilient with heat and cold, but less so with drought.
Plants are resistant to all but the coldest freezes. Tubers will happily live through the winter in soil that is frozen solid. It is beyond my ability to test, but I understand that sunchokes will survive winters down to at least USDA zone 4.
While they don’t mind winter cold, the plants don’t like a chilly summer. They grow tallest and yield best where summers are warm and humid with abundant rain. Where corn grows well, so do sunchokes. In my cool summers, varieties that grow 12 feet tall in the Midwest often struggle to reach six feet. They still produce plenty of food though and you can always plant a few more, but it is rare for anyone to report that they can’t grow enough sunchokes.
Photoperiod
Flowering and tuberization are both photoperiod dependent in Jerusalem artichokes. Sunchokes put all of their energy into growing the aerial plant until the length of daylight drops to about 13 hours in the fall. At that point, the plant changes its focus to reproduction and begins to form flowers and tubers. This is a bit of a race, because senescence comes very quickly afterward. Flowering is typically brief, lasting only a few weeks. The plants continue to direct energy in the tubers until the aerial plant is dead.
There are several day neutral varieties that will flower at any time of year and a few that will both flower and form tubers. These two traits are under separate genetic control, unfortunately (since it would be much easier to evaluate plants for early tuberization if early flowering were always coincident). The most common of these doubly day neutral varieties is ‘Stampede’. In North America, the late tuberization of the normal short day varieties is generally not a problem, so there is little advantage to growing a day neutral variety. On the other hand, if you are interested in breeding sunchokes, day neutral flowering varieties make the job a lot easier, particularly in wet climates. It can be hard to mature sunchoke seeds in a wet fall.
At tropical latitudes, where the day length is always short, sunchokes produce a crop in about four months from planting.
Soil Requirements
As I have already noted and will undoubtedly mention many more times, Jerusalem artichoke is a tough, weedy plant. It will thrive in moderately acidic to moderately alkaline soils, although it probably does best about neutral. It does like plenty of nitrogen, and will reward you with an abundant harvest in rich soil. Whether or not you need such an abundant harvest is another matter. I would generally prefer to save the rich soil for fussier crops and grow sunchokes in marginal ground or as the last crop in a rotation.
While sunchokes are quite tolerant of moisture, they need well drained soil like most root crops and will develop disease problems or rot outright in persistently soggy soil.
Propagule Care
Sunchoke tubers have a high respiration rate, so they quickly lose water to the environment, particularly in dry air. They will become soft and withered in just a couple of weeks without protection. The best place to store sunchokes is in the ground. The next best place is probably in a plastic bag in the refrigerator.
Planting
Because sunchoke tubers can withstand very cold temperatures and do not store very well, the best practice is usually to plant them whenever you have them. If you have a choice, it is probably best to plant tubers in the spring, simply because they are less likely to be lost to pests that way. There is no need to hurry if the tubers are stored appropriately, since most varieties won’t form tubers until the fall anyway.
Space plants four feet between rows to have a little walking room or three feet in a block. I find 16 in spacing in row is good for taller varieties and 12 inches for shorter. The smallest dwarf varieties can be spaced at 10 inches.
Large tubers can be cut into seed pieces as is commonly done with potatoes. As with potatoes, using the same knife to cut different tubers without sterilizing in between is a good way to spread disease. I have found that two inch seed pieces produce plants indistinguishable from the largest intact tubers.
Management
Hilling or ridging is not necessary for most varieties, but varieties that have very short rhizomes and tubers that clump at the base of the stem may benefit from some additional protection.
One of the common management problems with Jerusalem artichoke is keeping it under control. Many varieties have long rhizomes and will rapidly spread in every direction. Tilling at the wrong time can result in only increasing the spread. Sunchoke plants are at their most vulnerable in July, after the tubers have expended their energy and the plants have not yet begun to form new tubers. Several passes with a tiller in July and August are often enough to reduce a stand enough to finish it off with hand weeding.
Harvest
You can harvest Jerusalem artichoke any time after the plants die back. For most varieties, that will occur in the fall. If your use for the crop is subsistence and you live in a mild climate where the soil rarely freezes, as is true in the maritime Pacific Northwest, the best practice is usually to leave the tubers in the ground, harvesting as needed. This eliminates the problem of quality loss in storage and also exposes the tubers to colder conditions that generally improve flavor and digestibility.
Storage
Jerusalem artichoke tubers dehydrate quickly and will become soft and withered in as little as a week at low air humidity. Best storage conditions appear to be about 35 degrees F and 95% humidity. A plastic bag in the refrigerator works well if you don’t have a root cellar. Unless pests are a problem, the best place to keep sunchoke tubers is in the ground. If you need to harvest to make room, a clamp is a traditional way of storing root vegetables that works nicely with sunchokes. Essentially, you just dig a pit and then rebury all of your tubers mixed with a little soil.
Propagation
Sexual Propagation
True seed production in Jerusalem artichoke is complicated.
Problems
Diseases
Sunflower rust, caused by the fungus Puccinia helianthi, causes spotting and, in bad cases, defoliation. It seems to effect the plants most in the fall and I’m not sure if that is because wetter conditions favor it or because the plants lose resistance as they enter senescence. Either way, it is generally not as big a problem for sunchokes as it can be for sunflowers. The spores of P. helianthi can survive in soil for years, so disease tends to get worse over time and the only real solution is rotation to soil that has not recently grown host plants. There are many races of P. helianthi. Most are mild, but a few are particularly virulent, so a sudden worsening of the condition may indicate the arrival of a new strain.
Crop Development
It is unclear to what degree that the Jerusalem artichoke is a domesticated crop. Although there are varieties that were produced in breeding programs, the vast majority of varieties were taken directly from the wild and named. Now, are those, in fact, wild varieties, or are the best of these wild types actually relict populations of superior varieties that were once managed by native Americans. We don’t have enough information to know, but I tend to favor the idea that the Jerusalem artichoke is closer to a wild crop than a domesticated one. In terms of phenotype, at least, there is not a great distance between the traits found in the progeny of a wild type sunchoke and a domesticated variety. Both will give a pretty similar distribution, with a few superior types and a much larger number with small tubers on long rhizomes.
Most Jerusalem artichoke breeding in the past hundred years has been for industry, commonly with the goal to produce tubers with the highest possible inulin content. This is opposite to the goal likely to result in tubers that are good to eat. The list of improvements that would benefit the sunchoke as a garden vegetable is long, but a lower inulin content would yield a more digestible food and is, therefore, at the top of my wish list for this crop. Shorter rhizomes, a more compact habit, and day neutral flowering and tuberization all seem highly desirable. I think most people will have a preference for smooth skinned, non clumping tubers, since rough, clumping tubers are difficult to clean.
Relatively little progress has been made with this crop in the past four hundred years. The best varieties of today are little different from those described at first contact with the native Americans. The biggest hurdle for the sunchoke to overcome is to become a plant that people want to eat regularly. Since people don’t object to its flavor or texture and the plant produces reliably and abundantly, the path forward is clearly to improve the digestibility of the tubers.
My husband has planted Jerusalem artichoke, mainly for a friend who has diabetes (inulin is good for her). But I am worried about the rest of the garden. A neighbor complains that Jerusalem artichoke has taken over his whole yard, and he can’t get control of it. You said to dig out the tubers in the fall. Do you or anyone else have some additional advice for our neighbor’s problem?
This is a common problem with Jerusalem artichokes. Short of heavy herbicide use, about all that you can do is to cultivate shallowly and regularly over the course of a year to exhaust the rhizome. Planting is best done in an area well separated from the garden where they can’t do any harm. Otherwise, grow in containers.
Can you comment on allelopathy in sunchokes? A few sources mention it, but most don’t, and there seems to be disagreement about whether the effect is from root exudates or decaying plant matter amongst those that mention it at all. Eric Toensmeier reported on polycultures he was experimenting with, but I haven’t seen any results from that to suggest that any worked particularly well. A few people have suggested using them as a trellis for beans, but haven’t reported on their results, whereas others have pointed out beans as one of the things that specifically struggles to grow around sunchokes.
I’m not aware of any studies specifically with H. tuberosus, but H. annuus is widely reported to be allelopathic, so I would not be surprised if the whole genus is to some degree. I have not observed any clear cases, but that doesn’t mean it wasn’t there and I just didn’t recognize it. I don’t have any problem growing the other crops that I grow in rotation with sunchokes. It is usually the case that some plants are more susceptible than others though. Mostly, I just find that sunchoke growth is so rampant that it quickly overwhelms other plants. I wouldn’t be much inclined to try it in a polyculture because it just wants to be a monoculture. I find it best to give it a spot and let it go.
In regards to controlling the spread of the sunchoke plants, I planted my tubers in a large barrel planter. I was able to get a heavy plastic liner that fit inside the planter, and I drilled 1/2″ holes in the bottom of that. I placed the barrel on a square area of four 12″ x 12″ patio stones in our side yard. The plants grew to about 8 feet tall in full sun. They required lots of water because of our TX heat, and the plants bloomed profusely at the end of the summer. I have had no problem with the spread of the plants into the surrounding yard. I also planted Yacon tubers in 17-gallon $6 plastic tubs in the backyard. Both planting options seemed to handle the large plants very well, while controlling their spread. I have yet to harvest tubers, as I am waiting to have a good frost or two, but I am hoping to have a respectable amount. I am enjoying looking through your site. It is very helpful. Thank you.
I have had quite a different problem — after twenty years, one spring my Jerusalem artichokes didn’t return. I have no idea why they died out,but I have just ordered some here and hope to have them for 20 years!
I’ve found that pickling them seems to reduce the digestive distress. They’re super crunchy and I actually prefer them to cucumber pickles!