Two different goals
“Grow your own food” can mean two very different things.
- Grow your own vegetables. Fresh, tasty, and possible in a few hundred square feet.
- Grow your own calories. Enough food energy to live on. This takes much more land, labor and skill.
A calorie (strictly, a kilocalorie) is a unit of food energy. The gap between those two goals is the calorie gap. A garden full of vegetables can still supply only a small share of the calories you eat.
This lesson is about being honest with that gap, so you can set a goal you can reach.
How much energy a person eats
The Dietary Guidelines for Americans estimate that most adults need about 1,600 to 3,000 calories a day. The need depends on age, sex, size and how active you are. Physical farm work pushes it toward the top of the range.
Over a year, that is roughly 600,000 to 1,100,000 calories per person.
That is the number a fully self-sufficient homestead would have to grow, store and protect from pests and spoilage. For every person, every year, through good seasons and bad.
Not all food is equal
Foods differ hugely in calories per pound. These are rough values, rounded from USDA FoodData Central figures for raw or dry food:
| Food | Calories per pound, roughly |
|---|---|
| Lettuce | 70 |
| Tomatoes | 80 |
| Cabbage | 110 |
| Winter squash | 200 |
| Potatoes | 350 |
| Eggs | 650 |
| Dry beans | 1,500 |
| Wheat or dry corn | 1,500 to 1,650 |
| Cooking oil | 4,000 |
To get 2,000 calories, you would need to eat about 28 lb of lettuce, or under 6 lb of potatoes, or about 1.3 lb of dry beans.
Text description
A horizontal bar chart of rough calories per pound, rounded from USDA FoodData Central, raw or dry. Lettuce 70. Tomatoes 80. Cabbage 110. Winter squash 200. Potatoes 350. Eggs 650. Dry beans 1,500. Wheat or dry corn 1,500 to 1,650. Cooking oil 4,000. The first four are marked as low-calorie vegetables; the rest are staples, eggs and fats. A note says that 2,000 calories is about 28 pounds of lettuce, under 6 pounds of potatoes, or about 1.3 pounds of dry beans.
Staples or extras?
A staple crop is a food that supplies a large share of calories and stores well, like potatoes, grains and dry beans.
Is each crop a high-calorie staple, or a low-calorie vegetable?
- Dry beans
- Cucumbers
- Sweet potatoes
- Potatoes
- Kale
- Lettuce
- Wheat or other grain
- Tomatoes
Calories per square foot
Yield per square foot varies with soil, skill, water and climate. The figures below are our own rough illustration, not published values. We multiplied typical yields by the USDA calorie values above:
- Potatoes: about 100 to 250 calories per sq ft per season.
- Grain, such as wheat: about 80 to 125 calories per sq ft, often less for home growers.
- Dry beans: about 35 to 75 calories per sq ft.
- Lettuce: about 20 to 50 calories per sq ft.
So for one person living on 2,000 calories a day, potatoes alone would need roughly 3,000 to 7,000 sq ft (about 280 to 650 m²) each year. Nobody eats only potatoes, and a real diet needs protein, fat and variety. Each of those needs more land.
Text description
Left: range bars of rough calories per square foot per season, our own illustration from typical yields and USDA calorie values, not published figures. Potatoes 100 to 250. Grain, such as wheat, 80 to 125, often less for home growers. Dry beans 35 to 75. Lettuce 20 to 50. Right: two squares drawn to the same scale show the area one person would need to live on 2,000 calories a day from potatoes alone: about 3,000 square feet (280 square meters) at the high yield, and about 7,000 square feet (650 square meters) at the low yield, for a year. A real diet also needs protein, fat and variety, which take more land.
Published estimates of land per person vary widely. Many fall between about a quarter acre and an acre or more for a mostly plant-based diet, and more with meat or dairy. Those estimates assume farm yields. Home growers often get less, and need room for rotation, crop failures and storage losses.
Land is not the only limit
Land is often not the hardest part. Labor is.
- Grains need threshing and cleaning. Beans need drying and shelling. Potatoes need digging and a cool place to store them.
- Bad years happen: drought, hail, late frost, pests. A family that depends on its harvest needs a reserve.
- Climate sets your season length and water needs. A short northern season grows fewer crops per year than a long southern one.
- Fats and oils are hard to grow at home on a small scale. Many homesteads buy them.
Most people who try full food self-sufficiency find it is more than a full-time job.
A realistic goal
Many homesteads aim for something like this: most of their summer vegetables, eggs, some potatoes and squash for winter, and bought grains, oils and staples.
Set your household and the share of vegetables you want to grow. How much bed area is that?
About 141 lb of vegetables a year.
Bed area: roughly 170 to 460 sq ft, depending on skill, soil and season length.
Assumptions: Assumes about 0.35 kg (0.75 lb) of vegetables per person per day, and yields of 1.5 to 4 kg per m² per season.
Check
You want your garden to supply more of your winter calories. Which change helps most?
Summary
- An adult eats roughly 600,000 to 1,100,000 calories a year.
- Vegetables are low in calories. Staples like potatoes, grains and beans, plus fats, supply most calories.
- Full food self-sufficiency takes far more land and labor than most people expect.
- Start with vegetables and eggs, then add storable staples as your skill and soil grow.
Next, you will plan the kitchen garden.
Go deeper: protein, fat and nutrient balance
Calories are only part of a diet. People also need protein, fats, vitamins and minerals in balance. Beans and grains together give a fairly complete protein. Eggs add protein and fat. Dark leafy greens, though low in calories, are rich in vitamins and minerals. A home food plan that counts only calories can miss these. USDA FoodData Central lists nutrients for almost any food if you want to check your own plan.