How Much Garden You Would Need to 100% Survive On

[Hydrogen]

Could you grow enough food to feed yourself and your family if you wanted to—or needed to?

Gardening is often pitched as a relaxing, therapeutic activity—and it is relaxing and therapeutic! But it’s also a sign of how advanced society has become that we can regard growing food as a charming hobby instead of an absolute necessity. On the one hand, that’s a clear sign of mankind’s mastery over the world. On the other, it’s left us remarkably dependent on a system of farming and delivery logistics that has been shown to be distressingly fragile.

Anyone who has ever successfully grown a tomato plant in their backyard has wondered if they could go “off-grid,” grow their own food, and be done with their local supermarket. The answer is yes, but that’s the wrong question. The question isn’t whether it’s possible—the question is how. It’s all about the logistics: How much space do you need to grow enough crops to feed you and your family? Math will help you figure this one out.

Calculate the necessary square footage

If you’ve only ever gardened for fun, or to supplement your store-bought groceries with some tasty home-grown treats, you might not be aware of just how much space is required to feed someone. You may have noticed that family farms are kind of large, and there’s a very good reason for that (though some of that space was traditionally given over to livestock and draft animals). Estimates vary. Different crops require different amounts of space, for example, and some gardening gurus estimate you’d need at least 4,000 square feet per person, with more space allotted for stuff like lanes between crops.

Most of us don’t have 4,000 square feet to dedicate to gardening, but you probably don’t need quite that much as long as you’re efficient. A good rule of thumb is that you need about 200 square feet per person for a self-sustaining garden. So if you’re a family of four, figure you’ll need about 800 square feet, or a space about 20x40 or 10x80.

That’s ... still a lot of space, especially if you’re in an urban setting. The key is planning your garden out, because different crops take up different amounts of space, and if you’re going to live off of those crops you have to include a wide variety of plants for nutritional completeness. Your garden will need to include these:

• Proteins. If you’re going to survive on a garden, you won’t be eating meat. While nuts are an excellent source of protein, nut trees take up a lot of space, so make sure you plant beans. Growing lima beans on poles will require about six square feet of garden per person. Snap beans will take about 10 square feet and soybeans will eat up about 30 square feet.
• Carbohydrates. You’ll need some starch in your diet. The good news is that you have a lot of options. Beans will pull double duty here, in fact. Potatoes will require about 25 square feet per person, corn will require about 30 square feet per person, squash will need about six square feet, and peas need about eight square feet.
• Vitamins. A complete diet requires a load of nutrients beyond protein and carbs, so plan on including stuff like spinach (eight square feet per person), broccoli (eight square feet), kale (one square foot), or cabbage (10 square feet).
• Fruits. You can live on vegetables alone, but having some fruits is a great idea. Melons are great (six square feet per person), as are pumpkins (10 square feet), strawberries (10 square feet), and watermelons (six square feet).
• Medicinals & Spices. Some plants don’t offer much nutritional value, but make life a lot better by providing seasoning or health benefits. Some examples include cilantro (one square foot per person), garlic (four square feet), onions (eight square feet), and mustard (two square feet).

If you grow every plant we just discussed for a family of four, you’d need a garden space of approximately 754 square feet of garden—so the 200 square-foot rule tracks pretty well.

Here are the caveats to surviving on your own food

There are a few caveats here, or aspects of a survival garden you really need to think about before you decide that just because your backyard is precisely 200 square feet you’ll be able to pull this off. First of all, the list above isn’t comprehensive and only included a few examples. You might want things like carrots, okra, or cauliflower. This garden size calculator will give you some idea of how much square footage each crop requires. When planning your garden, the main rule is this: Grow stuff you want to eat. Growing food you despise is no way to live.

Other things to consider:

• Variety. Keep in mind that growing just enough food to survive on will wear on you over time. Sure, you could go full Mark Watney and try to live on potatoes alone (and you just might be able to with some supplements thrown in), but if you think entering year two of nothing but potatoes won’t be depressing, you’re kidding yourself. Keep in mind that variety is the spice of life, and diet variety will require more square footage.
• Seeds. Make sure you always select open pollinated seeds so you can recover seeds from your crops and re-plant.
• Spoilage. Growing food is a battle against nature. The moment your crops start to grow, hungry things will show up to eat them in the middle of the night, bugs will nest in them, and diseases will somehow find them. You’re going to need a margin of error if you’re going to live off your garden—and you will likely need a year or two to figure out what not to do and make adjustments to your plan.
• Design. There are many ways to lay out and manage a survival garden. Square foot gardens use raised beds and a grid system to maximize space, keyhole gardens are drought-resistant, and homestead gardens utilize a farm-like layout (and require more space). When planning a survival garden, look at the space you have and consider what kind of garden design will maximize your yield.

A survival garden can bring a lot of relief to your pocketbook and a lot of independence to your life—if you have the necessary space. Hey, no one said going off-grid was easy.


https://lifehacker.com/how-much-garden-you-would-need-to-100-survive-on-1848829190

....


This source claims an average of 200 square feet needed to produce adequate food for 1 person. Which conflicts with many claiming its impossible to grow sufficient food on 1 acre of land, which is 43,560 square feet.

I think it assumes the usage of chemical fertilizers, which are increasing in price due to them being manufactured from natural gas. While it may be possible to grow food in a reasonably small space, the dollar cost of soil, dirt, containers, compost, seeds, plants, mulch. And the man hours of care necessary could make the bar to entry prohibitive for many.

Money, experience and time appear to be the largest obstacles to solve for the world to fully embrace independent & organic food production.

[kaya11]

This is a good source for starters and compute necessary needs to start growing your foods. World War is possible and we could imagine food getting scarce so we better get ready before it really happens. We have more than 200 sq feet of garden, our back yard is full of greens. My father graduated in college of Agriculture and he started farming months ago. We have so many vegetables at the back yard and already started harvesting it and directs to kitchen for cooking. It is a nice feeling when you are eating the foods you grow. As of now we are planning to grow more and planning to plant avocado trees and mangoes. We just have to be patient, and make it possible with hard work. We hardly use any fertilizers, all we have is free animal dung and banana peels and others. Water is also abundant, especially this season which is rainy, we don't have to water them and have it easy.

[Captain Corporate]

Are we really sure this calculation is correct? I mean I haven't given a try myself so I can't say if it is correct or not but I have had gardens before, bigger than 754 square feet, one of them MUCH bigger than that, and I never really considered it. I mean don't get me wrong maybe I have no talent in it, or maybe this requires advanced farming techniques that I didn't consider, but it looks quite difficult. On the other hand, with the way hydroponics are going, it will be quite possible to grow enough food to make it "profitable" for people in a small room and still call it a business, we just need the equipment to get more affordable. So with that kind of tech, maybe this is possible in such a small space.

[Freeesta]

I think that such things should be done by specialists. What can you grow? What food? To grow something you need to work in the garden all day. Maybe bad weather and then the crop will not grow. It could be a hurricane, a tornado, a drought, anything, in some countries it may be sudden frost. I stand for the fact that every case should be done by a professional. And what seems simple is not always the case.

[24Kt]

Are we really sure this calculation is correct? I mean I haven't given a try myself so I can't say if it is correct or not but I have had gardens before, bigger than 754 square feet, one of them MUCH bigger than that, and I never really considered it. I mean don't get me wrong maybe I have no talent in it, or maybe this requires advanced farming techniques that I didn't consider, but it looks quite difficult. On the other hand, with the way hydroponics are going, it will be quite possible to grow enough food to make it "profitable" for people in a small room and still call it a business, we just need the equipment to get more affordable. So with that kind of tech, maybe this is possible in such a small space.

I can agree with you here. There are some people who can grow more than what they need and still make a business out of it. And just like the hydroponics method that you mentioned. Many people are already doing this type of gardening method. You don't need big space to survive. This is very subjective as it depends on the capability of the person when it comes to gardening. So some will say that they need big space to produce something. But if you are in a tight position and financial budget, you can make your small space a very productive one.

[hatshepsut93]

Money, experience and time appear to be the largest obstacles to solve for the world to fully embrace independent & organic food production.

Where would people who live in cities grow their food in such manner? And don't say "on rooftops".

This whole separation of labor thing allowed humanity to achieve everything that we have now, and everyone growing their own food would just result in us living in stone age again.

Also, in the last years of the Soviet Union a lot of its people did grow their food on dachas - people didn't do it because it's a fun activity, but because the economic situation pressured them to do so. I don't think that any country in the West is dire enough to massively shift to such system.

[adaseb]

This will not work for many people. Take people who live in New York City for example. They don’t own a home with a large garden. They can’t grow any food and vegetables.

Another issue is the weather. Many fruits and vegetables can only grow in certain climates. So you can’t rely on growing your own food year round if you live where it’s cold in the winter which is how it is with many people.

[philipma1957]

Could you grow enough food to feed yourself and your family if you wanted to—or needed to?

Gardening is often pitched as a relaxing, therapeutic activity—and it is relaxing and therapeutic! But it’s also a sign of how advanced society has become that we can regard growing food as a charming hobby instead of an absolute necessity. On the one hand, that’s a clear sign of mankind’s mastery over the world. On the other, it’s left us remarkably dependent on a system of farming and delivery logistics that has been shown to be distressingly fragile.

Anyone who has ever successfully grown a tomato plant in their backyard has wondered if they could go “off-grid,” grow their own food, and be done with their local supermarket. The answer is yes, but that’s the wrong question. The question isn’t whether it’s possible—the question is how. It’s all about the logistics: How much space do you need to grow enough crops to feed you and your family? Math will help you figure this one out.

Calculate the necessary square footage

If you’ve only ever gardened for fun, or to supplement your store-bought groceries with some tasty home-grown treats, you might not be aware of just how much space is required to feed someone. You may have noticed that family farms are kind of large, and there’s a very good reason for that (though some of that space was traditionally given over to livestock and draft animals). Estimates vary. Different crops require different amounts of space, for example, and some gardening gurus estimate you’d need at least 4,000 square feet per person, with more space allotted for stuff like lanes between crops.

Most of us don’t have 4,000 square feet to dedicate to gardening, but you probably don’t need quite that much as long as you’re efficient. A good rule of thumb is that you need about 200 square feet per person for a self-sustaining garden. So if you’re a family of four, figure you’ll need about 800 square feet, or a space about 20x40 or 10x80.

That’s ... still a lot of space, especially if you’re in an urban setting. The key is planning your garden out, because different crops take up different amounts of space, and if you’re going to live off of those crops you have to include a wide variety of plants for nutritional completeness. Your garden will need to include these:

• Proteins. If you’re going to survive on a garden, you won’t be eating meat. While nuts are an excellent source of protein, nut trees take up a lot of space, so make sure you plant beans. Growing lima beans on poles will require about six square feet of garden per person. Snap beans will take about 10 square feet and soybeans will eat up about 30 square feet.
• Carbohydrates. You’ll need some starch in your diet. The good news is that you have a lot of options. Beans will pull double duty here, in fact. Potatoes will require about 25 square feet per person, corn will require about 30 square feet per person, squash will need about six square feet, and peas need about eight square feet.
• Vitamins. A complete diet requires a load of nutrients beyond protein and carbs, so plan on including stuff like spinach (eight square feet per person), broccoli (eight square feet), kale (one square foot), or cabbage (10 square feet).
• Fruits. You can live on vegetables alone, but having some fruits is a great idea. Melons are great (six square feet per person), as are pumpkins (10 square feet), strawberries (10 square feet), and watermelons (six square feet).
• Medicinals & Spices. Some plants don’t offer much nutritional value, but make life a lot better by providing seasoning or health benefits. Some examples include cilantro (one square foot per person), garlic (four square feet), onions (eight square feet), and mustard (two square feet).

If you grow every plant we just discussed for a family of four, you’d need a garden space of approximately 754 square feet of garden—so the 200 square-foot rule tracks pretty well.

Here are the caveats to surviving on your own food

There are a few caveats here, or aspects of a survival garden you really need to think about before you decide that just because your backyard is precisely 200 square feet you’ll be able to pull this off. First of all, the list above isn’t comprehensive and only included a few examples. You might want things like carrots, okra, or cauliflower. This garden size calculator will give you some idea of how much square footage each crop requires. When planning your garden, the main rule is this: Grow stuff you want to eat. Growing food you despise is no way to live.

Other things to consider:

• Variety. Keep in mind that growing just enough food to survive on will wear on you over time. Sure, you could go full Mark Watney and try to live on potatoes alone (and you just might be able to with some supplements thrown in), but if you think entering year two of nothing but potatoes won’t be depressing, you’re kidding yourself. Keep in mind that variety is the spice of life, and diet variety will require more square footage.
• Seeds. Make sure you always select open pollinated seeds so you can recover seeds from your crops and re-plant.
• Spoilage. Growing food is a battle against nature. The moment your crops start to grow, hungry things will show up to eat them in the middle of the night, bugs will nest in them, and diseases will somehow find them. You’re going to need a margin of error if you’re going to live off your garden—and you will likely need a year or two to figure out what not to do and make adjustments to your plan.
• Design. There are many ways to lay out and manage a survival garden. Square foot gardens use raised beds and a grid system to maximize space, keyhole gardens are drought-resistant, and homestead gardens utilize a farm-like layout (and require more space). When planning a survival garden, look at the space you have and consider what kind of garden design will maximize your yield.

A survival garden can bring a lot of relief to your pocketbook and a lot of independence to your life—if you have the necessary space. Hey, no one said going off-grid was easy.


https://lifehacker.com/how-much-garden-you-would-need-to-100-survive-on-1848829190

....


This source claims an average of 200 square feet needed to produce adequate food for 1 person. Which conflicts with many claiming its impossible to grow sufficient food on 1 acre of land, which is 43,560 square feet.

I think it assumes the usage of chemical fertilizers, which are increasing in price due to them being manufactured from natural gas. While it may be possible to grow food in a reasonably small space, the dollar cost of soil, dirt, containers, compost, seeds, plants, mulch. And the man hours of care necessary could make the bar to entry prohibitive for many.

Money, experience and time appear to be the largest obstacles to solve for the world to fully embrace independent & organic food production.

Frankly you need chickens that lay eggs 🍳.

And many places wont let you have chickens.

I am a diabetic and need high protein low carb.

depending on what doctor you listen to maybe 25% of the human race needs high protein low carb diet.

I have 6000 feet to grow if I want. I grow basil , figs , tomatoes 🍅. Oregano.

Maybe  use 300 feet to grow.

[Lucius]

I grow organic vegetables and to a lesser extent some fruits (mostly raspberries, strawberries, chokeberries, currants) and I will just say for a start that it is not easy to produce healthy food. I do not use any chemicals in my cultivation, nor tap water that is full of chlorine, which is very harmful to plants. I also collect seeds every year, and I do the selection of the best seeds that again come from organic untreated seeds.

All this requires a lot of time, from planting seedlings already during the winter, taking care of it that lasts until spring when they are planted in the garden. Since the climate has changed, we now have to protect the plants with nets (hail&strong sun), which is an additional investment.

All this allows me to produce food for my family from spring to late autumn, and some of this food is used to make supplies for the winter. Tomato soup, peas, beans, garlic&red onion, carrots&parsley, and cucumbers can be stored and last us all winter, and we also have them fresh during the rest of the year.

I don’t know how big my garden is, but it’s not overly large and can produce food for 4-5 people. However, I must emphasize that this is an eco garden where it is much harder to keep plants healthy, which means that I had to learn how to produce eco plant protection products and fertilizer. In the end, I would certainly go cheaper to buy products in the store, but what I produce really has no price since it is 100% natural and healthy.

[stompix]

Carbohydrates. You’ll need some starch in your diet. The good news is that you have a lot of options. Beans will pull double duty here, in fact. Potatoes will require about 25 square feet per person, corn will require about 30 square feet per person, squash will need about six square feet, and peas need about eight square feet

Hmm, are you sure about this?

For potatoes, you quote 25 sqft per person, which seems to be 2.32 square meters.
The maximum yield for full industrialized production is 40 000 kilos per ha, 10 000 sqm, 4 kilos per sqm, so you will get 9.2 kilos of potatoes per person a year, or roughly 800 grams a month.
From personal experience, you won't get anywhere above 20 000 kilos for corn without going full hybrids and full treatment, this means even lower than potatoes, something at 500 grams a month.

Of course, I'm not happy with this damn imperial system so I could have done some mistakes but those numbers, at first sight, they are just bogus.

I don’t know how big my garden is, but it’s not overly large and can produce food for 4-5 people. However, I must emphasize that this is an eco garden where it is much harder to keep plants healthy, which means that I had to learn how to produce eco plant protection products and fertilizer. In the end, I would certainly go cheaper to buy products in the store, but what I produce really has no price since it is 100% natural and healthy.

Bro, weed out those strawberries 
As for the I have about 100m2 of raspberry and about the same of strawberries in a 5x40 greenhouse and they are just gone as they are getting ripe, it's been the second year with nothing left for jam. 
200 sqft, that's probably only enough for Barbie's dollhouse.

[iv4n]

I don’t know how big my garden is, but it’s not overly large and can produce food for 4-5 people. However, I must emphasize that this is an eco garden where it is much harder to keep plants healthy, which means that I had to learn how to produce eco plant protection products and fertilizer. In the end, I would certainly go cheaper to buy products in the store, but what I produce really has no price since it is 100% natural and healthy.

Bro, weed out those strawberries 
As for the I have about 100m2 of raspberry and about the same of strawberries in a 5x40 greenhouse and they are just gone as they are getting ripe, it's been the second year with nothing left for jam. 
200 sqft, that's probably only enough for Barbie's dollhouse.

Haha, he really needs to weed them out! It's too late here ( almost 9 pm and it's dark) I would take a picture of my line of strawberries... I will try to remember and do it tomorrow!

I have a small garden, something from everything, also I have 7 chickens (my daughter convinced me to take them) from a few weeks ago!
Just checked what 200sqft is, and I agree it's too small for anything really! I get what 100m2 is, the same math is here in Serbia, my garden is around 40m2 for now! I have a big yard (614 m2 with a house), but still in the progress to build it how I want! There's a lot of work to be done, I bought some additional yard (130 m2) and I am cleaning it for days (nobody got in there for years)!

Anyway, the point is that with my garden I can't survive for the entire year for sure! It's more to have something healthy at least and not to buy everything while it's a season! For now, I am not buying eggs, I am new in that area, it's a nice period, will see how it will go through the winter...

[paxmao]

I think that the land you would require depends a lot on the region you live in and the resources (water mainly) that you have a your disposal. Costs are also quite a critical consideration. In a wet and relatively cold location, there are not that many crops that do well in winter and the summer may be too short to grow a good quantity.

I personally only grow stuff from April to October, except for a few resistant crops out there. It is just a hobby and a way of getting some organic stuff I can fully trust. I would not consider that is particularly cheap.

[Hydrogen]

For potatoes, you quote 25 sqft per person, which seems to be 2.32 square meters.
The maximum yield for full industrialized production is 40 000 kilos per ha, 10 000 sqm, 4 kilos per sqm

They could be quoting outlier results, rather than mean averages.

Like these claimed results of 105 kilograms of potatos grown in 6 square meters, which works out to 17.5 kilos of potato produced per square meter.

I grew 235 lbs Of Potatoes in 200 sq ft Without Watering
https://www.youtube.com/watch?v=JrytUqXE9Ns

My attempts to grow potatos are an absolute horror show in comparison to his methods.  

My yields are ok though due to climate advantages. (300 inches of rain/year/avg)

[Lucius]

Bro, weed out those strawberries 
As for the I have about 100m2 of raspberry and about the same of strawberries in a 5x40 greenhouse and they are just gone as they are getting ripe, it's been the second year with nothing left for jam. 

I honestly don't bother much with strawberries🍓, they grow without too much effort - although I always plan to get as many varieties as possible and pay a little more attention to them. Since I'm allergic to something that producers spray strawberries on (and other fruits and vegetables), this is the only way I can eat them without looking like I've been stung by bees or wasps🐝

200 sqft, that's probably only enough for Barbie's dollhouse.

You’re right there, people can hardly estimate areas without ever really planting anything and doing gardening. Considering the safety nets I use, I estimate that I have about 150 m2 more or less, although the area is a bit bigger, but there is a space where I make compost and plant plants like comfrey that I use as fertilizer.

Of course, part of the area is also a flower garden, because a garden without colorful flowers is not a real garden🌼

[davis196]

If you want to survive by growing your own food the space inside your garden won't be enough.
You have to plant vegetables on your own(or rented) piece of property,somewhere in the fields.
This raises another question.Who is going to protect your vegetables from stealing?
Having access to water is really important.What if your property is too far away from a river or a lake?
There's not enough agricultural land for all the people in the cities,so I guess that the division of labor will be preserved.The farmers will keep farming and the people in the cities will keep doing their business.

[stompix]

For potatoes, you quote 25 sqft per person, which seems to be 2.32 square meters.
The maximum yield for full industrialized production is 40 000 kilos per ha, 10 000 sqm, 4 kilos per sqm

Like these claimed results of 105 kilograms of potatos grown in 6 square meters, which works out to 17.5 kilos of potato produced per square meter.

I grew 235 lbs Of Potatoes in 200 sq ft Without Watering
https://www.youtube.com/watch?v=JrytUqXE9Ns

235 lbs is 106 kg
200sqft is 18.5 sqm
It gets you 5.7 kg per sqm, nothing out of the ordinary for somebody who does this in order to get results.

While plants do technically grow out of thin air they still need nutrients to grow that big fruits or tubers or else, your average garden without aid won't be able to produce 20 kgs/sqm unless much of that is water, like cucumbers. And you can't live on cucumbers

I wonder what you tried to do with yours that went wrong, potatoes are quite resilient in growing, it takes art to mess them up . My specialty is growing cabbage with leaves opened up like a sunflower and harder than bamboo!

I honestly don't bother much with strawberries🍓, they grow without too much effort - although I always plan to get as many varieties as possible and pay a little more attention to them. Since I'm allergic to something that producers spray strawberries on (and other fruits and vegetables), this is the only way I can eat them without looking like I've been stung by bees or wasps🐝

I wouldn't use herbicide either on small plants with short flowering fruit cycles but you could help them a lot with a weed barrier. Obviously not that cheap HDPE or PEHD or whatever poly- thing but one sheet made out of wool and wood resin. Not going to last more than 4 years as it does discompose but nothing to worry about them either. The problem with weeds is that once you get some nasty stuff like knotgrass it will be a pain in the ass to get rid of it, you're going to feel the need to buy a flamethrower.

Back to the main topic, did a bit of math on those assumptions.

This source claims an average of 200 square feet is needed to produce adequate food for 1 person.

7 billion means 1.6 trillion sqft, so if the online convertor is right this is about 57392 square miles so we could feed the entire world if we raze Georgia to the ground and make it all agricultural land.
The metric system is simpler, 18.5 m2 per person,  148 000 km2, so ~ Sweden or Spain, and we have land for beaches and resorts left.
Seriously doubts those claims, it would mean  Lesotho would be needed to feed the whole of Africa.



If you can't see that tiny green dot there, I don't think you can see any reason to believe the claims either. 

[be.open]

There are very highly efficient progressive methods such as permaculture (smart forest) or aquaponics (aquaculture and hydroponics closed system cultivation) that allow you to get a lot of food even in a limited space, spending little effort or even fully automated. But I think that the problem of hunger on a planetary scale (and the breath of this horseman of the apocalypse is already close) will not be solved by progressive agricultural methods, but by a breakthrough in the field of pharmacology - a type of universal dry food for people approved by the dietitians association. Long term testing on pets doesn't seem to show any significant side effects from switching to dry food and clean water, I think the next step is to offer it to people. Of course, marketing efforts are needed to make people want to switch from natural food to dry food, but I think that this issue is completely solvable.

I think that natural food will very soon become a luxury that not everyone can afford - people will go to a restaurant on holidays and on special occasions to eat a steak or a lobster. And on weekdays, just eat a handful of these inexpensive tasty granules from the nearest pharmacy with a balanced composition, as well as the necessary set of vitamins and minerals - and do not worry about food anymore. My cat has been doing this for ten years every day and he's fine.

ps Technically, there is no problem making a Soylent-type universal nutrient liquid to solve the problem of food and drinking water in one blow, but without regular chewing, the gums weaken and the teeth begin to fall out, and this is an unpleasant side effect that I would like to avoid.

[Hydrogen]

235 lbs is 106 kg
200sqft is 18.5 sqm
It gets you 5.7 kg per sqm, nothing out of the ordinary for somebody who does this in order to get results.

While plants do technically grow out of thin air they still need nutrients to grow that big fruits or tubers or else, your average garden without aid won't be able to produce 20 kgs/sqm unless much of that is water, like cucumbers. And you can't live on cucumbers

I wonder what you tried to do with yours that went wrong, potatoes are quite resilient in growing, it takes art to mess them up . My specialty is growing cabbage with leaves opened up like a sunflower and harder than bamboo!

I see where I went wrong. Assumed 1 square foot = 3.3 square meters, when in reality its closer to 1 square foot = 0.1 square meter.

I put common dirt in a big plastic container. With wood chips, chopped tree branches, grass clippings, leaves. Sprayed water on it. Turned it to mix everything up. Its been decomposing for many months now. It looks and smells bad. That's what I'm using for my potatos. They're growing ok, it doesn't look beautiful. It looks like a swamp. Need to find a way to introduce more oxygen. Everything is too clumped together and choked off. Sawdust might work but am trying to see what type of results I can get without using electricity or modern conveniences.

Back to the main topic, did a bit of math on those assumptions.

This source claims an average of 200 square feet is needed to produce adequate food for 1 person.

7 billion means 1.6 trillion sqft, so if the online convertor is right this is about 57392 square miles so we could feed the entire world if we raze Georgia to the ground and make it all agricultural land.
The metric system is simpler, 18.5 m2 per person,  148 000 km2, so ~ Sweden or Spain, and we have land for beaches and resorts left.
Seriously doubts those claims, it would mean  Lesotho would be needed to feed the whole of Africa.



If you can't see that tiny green dot there, I don't think you can see any reason to believe the claims either.  

If 200 sq feet can produce 200 pounds of potatos in a 90 day period. And 200 lbs of potato might be "sufficient" food for 90 days on a rationing system.

I'm not playing devil's advocate. Perhaps we are planning for future potato world.

[Darker45]

My father lives in a rural town where there's ample of land for gardening or even farming. And he indeed grows his own food. Actually, the entire neighborhood is partially independent when it comes to food. They've got chickens, pigs, cows, goats. They've got all kinds of vegetables and fruits around, both planted and wild.

However, they're still not 100% self-sufficient. For example, there are still spices that they can't grow but they need everyday. They also need condiments that they can't produce. So they still have to go to the market every once in a while. But when worst comes to worst and survival is the only thing that matters, they could probably get by, at least in terms of food.

[oaz7t]

There needs one more factor to be added in the above theory and that's seasonal crops. You can not just have fertilised land and grow whatever food we want. We need it harvested according to the seasons. Too much rain and your wheat can't grow but definitely you can have good quality of rice in that season. Even with 2000 sq feet of space one can do miracles using the hydroponics cropping. Mutliple crops can be planted and have the dietary requirements achieved with the same.

Though article is pretty much convincing but it does need proper planning before one can achieve high quality crop cycles. For every crop cycle fertility of soil will reduce significantly and it may need additional steps such as halting crop harvesting in that land for particular period of time.

In that case we may need to grow on another apart of land until the previous one gets breathing.