The great big thread of sunchoke info - growing, storing, eating/recipes, science facts

Hey all, a while back I smuggled some sunchokes on the plane from British Columbia. This is a variety I have eaten and they were lovely. They are now stretching like mad in giant plant pots.

Will they survive/thrive if I plant them deep on a sunny slope and use cardboard and mulch to suppress the brome grass that currently dominates? They aren't going to get a lot of TLC -- but that's kinda the point.

I'd appreciate any wisdom you can give. I'm the new guy here.

Douglas Alpenstock wrote:Hey all, a while back I smuggled some sunchokes on the plane from British Columbia. This is a variety I have eaten and they were lovely. They are now stretching like mad in giant plant pots.

Will they survive/thrive if I plant them deep on a sunny slope and use cardboard and mulch to suppress the brome grass that currently dominates? They aren't going to get a lot of TLC -- but that's kinda the point.

I'd appreciate any wisdom you can give. I'm the new guy here.

Hi, Douglas. So Alberta, Saskatchewan and Manitoba? They grow very well in my sandbox [central WI zone 4b] and will survive even lower temps than indicated [like -40F] and come back for an encore year after year, provided the deer don't nibble on them too much in the baby stage.
You don't tell us what kind of soil you have. This site indicates a few more things about what sunchokes like and don't like: see how well your soil matches:
https://greg.app/jerusalem-artichoke-hardiness-zone/#:~:text=Jerusalem%20artichokes%20are%20remarkably%20resilient,thrive%20even%20when%20temperatures%20dip.
It helps to keep them bound: When the growing root encounters an obstacle, that's where the tuber starts forming. I have mine in beds for that reason. Also, the garden is fenced. If I forget to close the fence, the deer come and can devastate a young patch pretty fast.

They grow in my northern Minnesota sand, but I don't get the bumper crops that I see others harvesting online.

Christopher Weeks wrote:They grow in my northern Minnesota sand, but I don't get the bumper crops that I see others harvesting online.

I too have a very sandy soil, and I suspect that sunchokes really like lighter soil. When I lived in Vesper [very clayish soil] I had fewer tubers, even though they were just a bit bigger.
As far as "the bumper crops that I see others harvesting", we tend to think of sunchokes as an indestructible tuber that loves neglect. That's not quite true: if we want bumper crops, we have to nourish that crop and limit the weeds or we'll get pretty puny and twisted tubers, just like any other crop.
Besides a soil in which they can freely expand [like sand] they need to get a bit of chicken manure or comfrey tea for good sizes, although genetics will still limit them to a good sized fist at most. As far as the shape, the first year, sunchokes will grow a pretty round tuber, but those that are left in the ground will grow in many directions, making this left tuber "very knobby", and not really larger.
That's why I try to grow them in beds [they escape anyway] or in big tubs so that i can harvest all of them, thus staying in complete control. Even a tiny thumb sized tuber [or a piece of one!] will make a full size plant the following year.
As the temps go down, so do the tubers: They dive down for protection, and going down a foot or 1.5 ft is not uncommon, especially in sand. [The first tubers to form seem to form closer to the surface and the mother plant. at the end of the year, they seem to take a nose dive].

Considering they do well at Wheaton Labs near Missoula, MT and we have them growing here (some have started to market them commercially as well) in southern MB, you should certainly be able to grow them.  We have pretty heavy soil here, so they aren't likely to be as nice and abundant as some others experience, but I have lots of space to fill, so I don't mind if they simply form patches that show their lovely yellow flowers.

Derek Thille wrote:Considering they do well at Wheaton Labs near Missoula, MT and we have them growing here (some have started to market them commercially as well) in southern MB, you should certainly be able to grow them.  We have pretty heavy soil here, so they aren't likely to be as nice and abundant as some others experience, but I have lots of space to fill, so I don't mind if they simply form patches that show their lovely yellow flowers.

Towards the end of the season, sunchokes do make beautiful, tiny sunflowers, but those never seem to make seeds, unfortunately.
Another use for these bountiful tubers is fodder for pigs, chickens, goats. etc. [After harvest, I select any tuber that  is too tiny, was damaged by the spade [I use my hands & sometimes a fork] to give to my chickens. The rest, I store in homer buckets with damp sand, in an unheated garage, to eat and for seed next year.
Right around deer hunting -don't tell the warden- some damaged ones will find their way on a deer trail. They are grateful, then we are grateful for sunchokes [Helianthus tuberosus]
You could also just grow it as a dense wind barrier if your area is windy, but I prefer to use sunflowers (Helianthus annuus) which, as the name indicates is an annual, for that: There is a variety that is very large and tall [I'm talking about one that has stems the size of my wrist!! and is nearly 10 ft.]. Also, the sunflowers will give you seeds, whereas sunchokes don't for short season areas. These tall sunflowers, if left undisturbed will leave a tall erect barrier on which you could grow vines to fill gaps and make an even better wind barrier. I'm saying that because I heard that Southern Manitoba is quite windy.
Wink wink.

Cécile Stelzer Johnson wrote:

Derek Thille wrote:Considering they do well at Wheaton Labs near Missoula, MT and we have them growing here (some have started to market them commercially as well) in southern MB, you should certainly be able to grow them.  We have pretty heavy soil here, so they aren't likely to be as nice and abundant as some others experience, but I have lots of space to fill, so I don't mind if they simply form patches that show their lovely yellow flowers.

Towards the end of the season, sunchokes do make beautiful, tiny sunflowers, but those never seem to make seeds, unfortunately.
Another use for these bountiful tubers is fodder for pigs, chickens, goats. etc. [After harvest, I select any tuber that  is too tiny, was damaged by the spade [I use my hands & sometimes a fork] to give to my chickens. The rest, I store in homer buckets with damp sand, in an unheated garage, to eat and for seed next year.
Right around deer hunting -don't tell the warden- some damaged ones will find their way on a deer trail. They are grateful, then we are grateful for sunchokes [Helianthus tuberosus]
You could also just grow it as a dense wind barrier if your area is windy, but I prefer to use sunflowers (Helianthus annuus) which, as the name indicates is an annual, for that: There is a variety that is very large and tall [I'm talking about one that has stems the size of my wrist!! and is nearly 10 ft.]. Also, the sunflowers will give you seeds, whereas sunchokes don't for short season areas. These tall sunflowers, if left undisturbed will leave a tall erect barrier on which you could grow vines to fill gaps and make an even better wind barrier. I'm saying that because I heard that Southern Manitoba is quite windy.
Wink wink.

Thanks.  Yes, it can be windy.  At the top of the hour, Windypeg had winds from the NW 34 gusting to 45 km/hr (21-28 mph).  That isn't too bad, but it will wear you down if you're out working in it all day.

In September at Wheaton Labs, we planted sunchokes along the top of a berm for an added privacy hedge (and perhaps to make the occupants of Base Camp a bit windier).  I've planted some on top of a smaller berm (created for the 2025 GAMCOD) with the hopes it will do something similar for us.  

I do have another patch developing a bit east of the main garden - along with a Nanking cherry hedge to the south, we may eventually get some respite from the wind in the garden.  I guess for the next couple of years, I ought to focus on harvesting some to be able to create more hedging.  

With your note about climbing the sunflowers (Mammoth Russian is on variety in these parts that gets tall), perhaps growing peas or some beans up the sunchokes every few years may help replenish nitrogen in the soil for them.

We have conventional ag on two sides of our acreage, so annuals are at greater risk from toxic gick than established perennials.  We did have quite a stand of black oil sunflowers along one side the one year which the bees and the birds appreciated and there was some self-seeding.

If you are looking for big enough to eat seeds, no, they don't do that. But if you want viable seeds you need more than one variety. I have 6 types in my patch and the flowers have viable seeds.

I actually dropped it here to make y'all laugh. We have had excess rain this spring, flooding etc. Someone was here today, asked me what they were, recognized the name Jerusalem Artichoke, looked at them, they are about 8 feet tall right now, in late June. He asked me how tall they would get. "Normally 12 feet or so by October. At the rate they are going, probably 16 feet or maybe more this year." He was stunned....
I pointed out that I sited them where there is water flow off the neighbor's yard, that comes down through several yards every time it rains, and tends to wash away all of their topsoil. The Sunroots like that spot! Especially when it is flooding rain. The topsoil doesn't make it past them any more, nor does much of that flowing water.
Happy rowdy sunroots!
:D

Cécile Stelzer Johnson wrote:Hi, Douglas. So Alberta, Saskatchewan and Manitoba? They grow very well in my sandbox [central WI zone 4b] and will survive even lower temps than indicated [like -40F] and come back for an encore year after year, provided the deer don't nibble on them too much in the baby stage.

You don't tell us what kind of soil you have. ...

It helps to keep them bound: When the growing root encounters an obstacle, that's where the tuber starts forming. I have mine in beds for that reason.

Excellent information -- just what I'm looking for. Thank you!

Our "soil" is a fine silty sand mix. But I'm holding them in 16w x 12+d tree pots I scrounged, with a mix of compost, char, and half-digested wood chips. They clearly love it! I have eight vigorous tubers, and I can get more.

If they like to be bound, I can adjust that to one plant per pot and plunk them deep into the ground, flush with the soil surface. And then we'll see!

BTW, would they be fussy about well water that is somewhat alkaline (basic) -- high TDS? My captured rain water is precious stuff.

Christopher Weeks wrote:They grow in my northern Minnesota sand, but I don't get the bumper crops that I see others harvesting online.

Do you have enough sunlight for them to grow leaves? Here is a plant I pulled up today. As you see the stolons are forming and the end are bulging. It's still months away from blooming time and they are already constantly sending sugar down the roots for storage. If you have lots of biomass but tubers are less than expected, consider the possibility that sugar transfer is delayed due to boron deficiency. It's a common deficiency with sand soil and it's easy to fix.

Douglas Alpenstock wrote:

Cécile Stelzer Johnson wrote:Hi, Douglas. So Alberta, Saskatchewan and Manitoba? They grow very well in my sandbox [central WI zone 4b] and will survive even lower temps than indicated [like -40F] and come back for an encore year after year, provided the deer don't nibble on them too much in the baby stage.

You don't tell us what kind of soil you have. ...

It helps to keep them bound: When the growing root encounters an obstacle, that's where the tuber starts forming. I have mine in beds for that reason.

Excellent information -- just what I'm looking for. Thank you!
Our "soil" is a fine silty sand mix. But I'm holding them in 16w x 12+d tree pots I scrounged, with a mix of compost, char, and half-digested wood chips. They clearly love it! I have eight vigorous tubers, and I can get more.
If they like to be bound, I can adjust that to one plant per pot and plunk them deep into the ground, flush with the soil surface. And then we'll see!
BTW, would they be fussy about well water that is somewhat alkaline (basic) -- high TDS? My captured rain water is precious stuff.

Wow, you are really babying them, Douglas. Compared to my sand box, they are in sunchoke nirvana as far as soil! I suppose you felt the need to start them in a smaller container?  [16" wide by 12" deep is nowhere near enough soil for these vigorous growers].
I've put them in beds [4'X8'] so with no bottoms. That's how I know they can go deeeep,  and now, I use half barrels [the blue 55 gallons kind]. Cut in half, and with a few 1/4" holes for drainage about 3" up from the bottom, that makes a fine planter that I can use also for my potatoes. In the fall I can dig them out with my hands or turn the half barrel upside down. [Just don't water for the last couple of weeks or it will be too heavy!]
As far as for water, Douglas, you are in luck: It turns out they *prefer* slightly alkaline soil: Mine is on the acid side at 6.5, so not too bad.
https://www.smartgardener.com/plant/33-jerusalem-artichoke#:~:text=Soil%20Preference&text=Jerusalem%20Artichoke%2C%20or%20Sunchokes%2C%20will,more%20in%20slightly%20alkaline%20soils.

Some notes on harvesting sunchokes throughout the year.

They can be harvested while buried in snow. In Montana, that means late December through March. They are intact and fresh. Some folks report a sweeter taste and less "comedy" (intestinal gas) for those that have over-wintered.

We've observed that the tubers begin softening and shriveling-up starting in early- to mid-June. You might be able to dig around and find some more that are still in edible condition if you find large, dry stalks at that time of year (over 1" / 3cm diameter). Everything else seems to be making new stalks, and that's where all the stored energy is going.

We will be checking to see how early we can harvest them. But in general, typical harvests begin after the flowers are gone, and the stalks are drying up. In our case, that typically means mid-October.

Western Montana's sunchoke harvesting season: late October to mid-June.

Stephen B. Thomas wrote:Some notes on harvesting sunchokes throughout the year.
They can be harvested while buried in snow. In Montana, that means late December through March. They are intact and fresh. Some folks report a sweeter taste and less "comedy" (intestinal gas) for those that have over-wintered.
We've observed that the tubers begin softening and shriveling-up starting in early- to mid-June. You might be able to dig around and find some more that are still in edible condition if you find large, dry stalks at that time of year (over 1" / 3cm diameter). Everything else seems to be making new stalks, and that's where all the stored energy is going.
We will be checking to see how early we can harvest them. But in general, typical harvests begin after the flowers are gone, and the stalks are drying up. In our case, that typically means mid-October.
Western Montana's sunchoke harvesting season: late October to mid-June.

That pretty much track what we see in Central Wisconsin zone 4b, but really, as long as the ground is not frozen, we can put them in or take them out. if we are smart with storage [homer pail with damp sand in a frost free storage shed], we can pretty much enjoy them all winter. You are also correct about them being sweeter after a light frost.
As far as intestinal distress, I eat the white ones raw, boiled, mashed, and my first eating of the season is a smallish portion!.
I planted some red ones once. Those truly deserve the name "fartichokes" and I won't plant them any more.

I wholefartedly agree with Cécile. I have a white skinned very knobby variety and a reddish/purple skinned smooth skinned variety. The white ones lose their zip fairly easily, cooking for 1/2 hour, canning as pickles, over winter freezing, etc. Those red ones! I live in zone 5, east/central PA. I can dig them in the spring, after a full winter's freeze and cook them for an hour and I still raise the roof, but they taste so much nuttier and better than the white ones. I also take a daily supplement of Inulin for gut health which is the gastronomical ingredient in 'chokes. That means I should have guts balanced to withstand the Inulin in 'chokes, but I repeat * those red ones! *
I harvest only after the stalks are fully dead and dried. That's when all the nutrients have drained into the tubers and they're at their best size and flavor, just like harvesting potatoes, only after the stalks are dead and dry.

Cécile Stelzer Johnson wrote:16" wide by 12" deep is nowhere near enough soil for these vigorous growers.
I've put them in beds [4'X8'] so with no bottoms. That's how I know they can go deeeep,  ...

I appreciate the advice. I will dig a trench then, with some amending to increase water retention and nutrients. Maybe I can line the trench walls with junk wood to irritate them into producing new tubers. How close together would you plant them?

How close together? The white knobby ones I have only spread about 12" or thereabouts so I start with them between 2' and 3' apart when I'm starting a new patch. The reddish ones can spread around 3' so you could go 6' apart if you want. It totally depends on the variety. Consider this though, after the first year, it just doesn't matter. Every tiny tuber you miss will sprout in the spring. They could be an inch apart or four feet. Don't sweat it. I normally plant them about 3" to 4" deep, just so long as they're deep enough that predators can't get them too easy. Rats, voles, squirrels, rabbits and the occasional groundhog. Voles are the ones to watch out for, they can be voracious.

Douglas Alpenstock wrote:

Cécile Stelzer Johnson wrote:16" wide by 12" deep is nowhere near enough soil for these vigorous growers.
I've put them in beds [4'X8'] so with no bottoms. That's how I know they can go deeeep,  ...

I appreciate the advice. I will dig a trench then, with some amending to increase water retention and nutrients. Maybe I can line the trench walls with junk wood to irritate them into producing new tubers. How close together would you plant them?

Blaine Clark is spot on: it depends on the variety. I had a variety that didn't spread much [like a 2 ft diameter, with most of the tubers close by], but I've also had some that went 6 ft in all directions and I just could not retrieve them all. the following year, they were all over the garden and it took me another 2 yrs of hunting them to get them all.
As far as putting solid wood, go ahead, but sunchokes will take the shape of your wood. When I planted them in bed, I had one or two that tried to pass under my bed boards. they ended up oddly shaped. Still smooth, mind you, just concave around the wood.
I planted them just to cover them. No need for a trench. [They seem to lower themselves to the depth they need anyway.]
But there too, I'd listen to Blaine: Voles are VORACIOUS!  That another reason I plant them in half barrels now.
Is it a named variety? That might help us guess at what they'll do.

I planted 2 different kinds on July 15th and July 16th. Zone 4b WI, in the ground. Zone 4b MN, in containers.

One is Red Fuseau and the other I don't know but more yellow, not very knobby.

It's pretty late to get a harvest this year but I just couldn't wait until spring.

I planted some 20 years or so ago and I can't even remember exactly where. I know I harvested and ate some. I suspect I read about them being "invasive" and made sure to eradicate with a tiller. I have other sunflowers growing I suspect could be wild ones. they will only really grow if fenced or the deer will eat them to the ground. I'll dig some of those this fall and see if there are any tubers.

J Katrak wrote:I planted 2 different kinds on July 15th and July 16th. Zone 4b WI, in the ground. Zone 4b MN, in containers.
One is Red Fuseau and the other I don't know but more yellow, not very knobby.
It's pretty late to get a harvest this year but I just couldn't wait until spring.
I planted some 20 years or so ago and I can't even remember exactly where. I know I harvested and ate some. I suspect I read about them being "invasive" and made sure to eradicate with a tiller. I have other sunflowers growing I suspect could be wild ones. they will only really grow if fenced or the deer will eat them to the ground. I'll dig some of those this fall and see if there are any tubers.

Hi, neighbor, [I'm in zone 4b WI, in the "central sands"]
Sunchokes and sunflowers are in the same family, but in our zone, the sunchoke flowers will be tiny [2" diameter max] and you won't get seeds.
As I'm sure you know, mid July is quite late to expect a crop. You could try and see, when you are ready to harvest, what they did. If the tubers are just tiny, leave them in and your planting job is done for next year, even those that are in containers. I did try Fuseau one year. My tummy could not take them in. Cramping was baaaad. Even cooked, I could not eat very many, and I really like them!
If you planted them in the ground, they are extremely persistent: Even a tiny knob will grow in a full sized plant, so anytime the ground is open is a good time to plant them. [You just might not get that big of a crop].. I have harvested them out of a container [Half of a 55 gallon blue plastic barrel], sorted them out and replanted a couple of days later.
They will keep in a damp bucket of sand in your garage over the winter... or right where you planted them originally.
Stampede is  good cultivar, less knobby.
Good luck with yours!

Hi Cécile, Thanks for relaying your experience. That's what I was hoping to hear!

Yep, it's an experiment and one less thing to plant next spring. I'll post back after first freeze when I get a chance to see how they turned out.

Too bad about the cramping. Yikes. Good thing there are other kinds!

The wild ones look more and more like sunchokes too me from descriptions and photos. I'm excited to find out. They have small flowers now and more are coming. If anything, that seems like maybe it's a bit early.

Some mid-summer observations about sunchokes. Paul wanted to take a number of tubers out to a potluck event so that others could plant them, so I chose about a dozen plants to dig up and then documented what I noticed.

These are from 1st August, and I don't recommend trying to harvest round this time since the tubers are so tiny. Most of the energy stored in the original tuber seems to have gone up to fortify the stalk. None of the sunchoke stalks I harvested seemed to be "at maturity," and they had no flowers growing at the tops of the stalks. However, we do have some of those at the other chunk of property and I opted to let those continue to grow. I am still unclear as to what is the best set of conditions for sunchokes: focusing on access to water, or soil, etc. Which is the most-impactful lever to adjust...? I don't have an answer just yet.

Here's a photo of baby sunchokes growing at the base of the stalk.



An image of the root system. You'll notice a brown "husk" of sunchoke left somewhere near the base, In this image, a stolon/baby tuber is actually poking through that husk.



Here's more detail of a former tuber, and where it connects to the stalk at the base. The original tuber is completely hollowed-out and has left nothing but a shriveled brown husk.



Hopefully these are useful and/or sate someone's curiosity.

Stephen B. Thomas wrote:Some mid-summer observations about sunchokes. Paul wanted to take a number of tubers out to a potluck event so that others could plant them, so I chose about a dozen plants to dig up and then documented what I noticed.
These are from 1st August, and I don't recommend trying to harvest round this time since the tubers are so tiny. Most of the energy stored in the original tuber seems to have gone up to fortify the stalk.  I am still unclear as to what is the best set of conditions for sunchokes: focusing on access to water, or soil, etc. Which is the most-impactful lever to adjust...? I don't have an answer just yet.

You are correct, Stephen:  When the original tuber is placed in the ground, its only function is to grow a strong stalk from which big leaves will grow. That is true of all plants, really.
Later, with the sun doing its thing, the leaves will convert the sun's energy into food, and that in turn will develop the tubers, which are storing the energy over the winter for the following year. Pretty much all biennials and tubers do this, because they store energy for the next year.
As far as "the best lever" for optimal production, It is easier to check in the abstract what is the best and correct your site if it deviates too much. This is what Smart gardener says:
"Soil:
Loose and well-drained: This is crucial to prevent tuber rot and facilitate harvesting.
Prefers sandy loam: This texture is ideal for tuber expansion and easier digging.
Tolerates various soils: Even nutrient-poor or rocky soils will support sunchokes, though yields may be smaller.
pH between 5.8 and 6.2 (slightly acidic to neutral) is ideal, although they can tolerate a broader range from 4.5 to 8.2.
Adding compost or other organic matter improves soil structure and nutrient content.
Water:
Consistent moisture, especially during establishment and tuber development: Water deeply at least once a week, providing about 1 inch of water.
Drought tolerant once established: They can survive with less water, but yields may be reduced.
Avoid waterlogging: Prolonged wet conditions will rot the tubers.
Mulching helps conserve soil moisture and reduce the need for frequent watering.
Sunlight:
Full sun: Sunchokes thrive in full sun, meaning at least 6 hours of direct sunlight per day, according to the North Carolina Extension Gardener Plant Toolbox.
Partial shade tolerated: They can grow in partial shade (2-6 hours of direct sunlight) but may not produce as many tubers or flowers.
In summary, for the "perfect" sunchoke growing environment, aim for loose, well-drained, fertile soil, consistent watering during the growing season, and plenty of sunlight. While they are very forgiving plants, providing these ideal conditions will result in the largest and most flavorful tubers. "
I would only that in Wisconsin, famous for growing potato *tubers*, their first "shot in the arm" for tuber development is nitrogen, which precisely helps to the development of the top foliage, for a big plant, and then, about 40 days before harvest, they add a hefty dose of phosphorus and calcium [we are talking about *commercial* growers, so they figured out what, in the bonemeal, makes the tuber grow.
You can probably achieve the same result if you add bonemeal at planting time because it is a low-release amendment that is rich in phosphorus and calcium.

This is my second patch of sunchokes. They were planted late fall of 2023. It's 2/3 Lofthouse sunchokes and 1/3 mixed others. I only harvested a few around the back right (in this picture) edge last fall. Last year they grew fewer plants, but each seemed more vigorous -- thicker stalks, taller, more flowers.

What happens to a patch that you don't harvest? Once? After years? And what's the yield like after neglect? I'm trying to gauge how important it is to disrupt the whole patch.

And if you don't have especially friable soil, how do you harvest at a reasonable speed? I find this takes hours of hard work to get relatively few. I have a half inch of soil, eight inches of sand(y loam), and then dozens of feet of sand and rocks that have compacted somehow even without much clay.

Christopher Weeks wrote:This is my second patch of sunchokes. They were planted late fall of 2023. It's 2/3 Lofthouse sunchokes and 1/3 mixed others. I only harvested a few around the back right (in this picture) edge last fall. Last year they grew fewer plants, but each seemed more vigorous -- thicker stalks, taller, more flowers.

What happens to a patch that you don't harvest? Once? After years? And what's the yield like after neglect? I'm trying to gauge how important it is to disrupt the whole patch.

And if you don't have especially friable soil, how do you harvest at a reasonable speed? I find this takes hours of hard work to get relatively few. I have a half inch of soil, eight inches of sand(y loam), and then dozens of feet of sand and rocks that have compacted somehow even without much clay.

Yes, that is normal: "Last year they grew fewer plants, but each seemed more vigorous -- thicker stalks, taller, more flowers."
The picture shows very crowded sunchokes. Once you harvest a few, that leaves room for others; it disturbs the soil, making it easier for new sunchokes to enter and thrive, pushing through unoccupied soil.
"I'm trying to gauge how important it is to disrupt the whole patch". It is quite important. If you do not harvest, they tend to multiply erratically and they eventually overcrowd each other, leading to diminished yields, smaller tubers, more contorted tubers. You say you have loam under there: These sunchokes should do especially well. The lower strata, however, being sand and rock, may make it devilishly hard to harvest the tubers.
You do not mention deer pressure, and that's surprising to me because they love the young tips as much as I love asparagus, and they will keep coming night after night, snipping everything they can in the spring. That will eventually kill a patch that is not fenced, as the plant is never allowed to grow to its full stature, so it cannot grow tubers either.
The patch also needs a little TLC: Whenever a plant grows, it takes specific nutrients from the ground. They need to be replaced, or there will not be enough of the *right* nutrients for tubers to grow.. [That's why crop rotation].
"If you don't have especially friable soil, how do you harvest at a reasonable speed?"
Hmmm why is speed important to you? You can take it easy with this crop, as you can harvest whenever the ground isn't frozen...
The main problem with sunchokes is: "Have roots, will travel!". I had some that would spread 6 ft in every direction and 3 ft down [at least!] Some may have gone deeper, but I did find some 3 ft deep. If they are planted close, their roots mingle, adding to the trouble! [Ask Oikos, if they are still in business: they had some cultivars that didn't stray too far from momma.]
I find it very important to grow them in large 1/2  of those blue 55 gallon barrels, where they cannot spread. I get to choose the soil [I just have to amend my sandbox a bit and water, so I can usually dig them out by hand], and they can't go farther than the barrel where they are confined. At harvest time, I do one barrel at a time, and I just use my hands. If I don't get the whole thing harvested, there are quite a few days, even after frost, when I can dig for them. I can cover them if it rains a lot, because turning over a half barrel that is full of wet soil is too hard for me to do!
Another point: I try to harvest every one of them, as the first year, the young tubers will be relatively round. The second year, a tuber that is left in will start to grow its own roots in a tetra shaped fashion.[some up, some down, some left, some right] That tuber will still be good to harvest,[They survive, even in a barrel outside in Wisconsin zone 4b winters] but it will have all sorts of growths, arranged  along 4 "spines" so to speak, going from front to back. That will make it harder to use, as you may have some crevices where soil lodges..
I think that you may be dreaming of a food forest that you could harvest only when and if you want to? This crop is relatively easy, but it doesn't *thrive* on neglect. With the 10 half barrels or so that I use, I can grow much more than I need, giving some to my chickens as well, and harvest is EASY. I harvest in the fall, in the winter as long as the ground isn't frozen, and I harvest in the spring too.
I'm glad I made the switch from "in the open ground" to in barrels. I also have more room for the other things I want to plant, so it's a win-win for me.
If you are a hunter, deer love sunchokes almost as much as they love apples... Just saying...

I want to read this and think about a response with some time, but to answer your simplest question, our ground is frozen from the end of October through the end of April. And that’s why I need to hurry with my harvest.