Most vegetable gardens in Britain are built around salad, courgettes, runner beans and tomatoes. They are pleasant, they are what the seed racks sell, and between them they produce almost no food energy at all.
If the reason for growing is resilience rather than enjoyment, the crop list changes completely, and so does the honest expectation of what a garden can do.
The arithmetic nobody does
Worth doing once, because it reframes everything.
A typical raised bed of 1.2 by 4 metres is about 5 square metres. At best that is around two weeks of one person's energy, once a year.
A standard UK allotment plot is around 250 square metres. That is, very roughly, one adult's calories for a year if the whole thing were potatoes and everything went well.
This is not an argument against growing food. It is an argument for knowing what growing food does, so the effort goes to the right crops and the expectations are real. A household that thinks its vegetable patch is a food supply has made a planning error; a household that knows it is a contribution has not.
The library page on food carries the stored calorie backbone, and the relationship between the two is the point: stores are the supply, the garden is the extension. See the food chapter.
What actually returns energy
Potatoes first, by a wide margin. They are also easy, they break up ground, they suppress weeds, and children like harvesting them. See potatoes.
Jerusalem artichokes deserve a warning as well as a recommendation. They yield enormously with almost no attention and store themselves in the ground through winter. They also contain inulin, which many people cannot digest comfortably and which causes significant wind, and once planted they are extremely difficult to remove. Grow them somewhere you are content for them to stay, and introduce them to the diet gradually and in small quantities.
Winter squash is the other big one, because it stores for months in a cool room with no processing at all. It needs a lot of space and a decent summer.
Grain is not worth growing on a garden scale. The area required is large, and threshing and winnowing by hand is far more work than people imagine. Buy and store grain instead.
The crops that are mostly water
Not useless, and not food supply.
- Lettuce and salad leaves. Almost pure water. Valuable for vitamins, morale and fresh food in the hungry gap, and irrelevant to energy.
- Cucumber, courgette, marrow. Enormous volume, negligible calories. A courgette glut feels like abundance and is mostly water.
- Tomatoes. Wonderful, and low in energy. Worth growing for flavour, and worth preserving.
- Runner and French beans, eaten green. Modest. The same plants left to dry produce actual food. See below.
- Radish, spring onion, herbs. Flavour and speed, not substance.
Grow these, and grow them because morale, vitamins and variety are genuine needs. Just do not count them.
Protein
The nutrient a garden struggles with most, after fat.
- Dried beans and peas. Leave runner, French, borlotti or field beans to dry fully on the plant, then shell and store. Yield per square metre is low and the product keeps for years, which is what makes it worth the ground.
- Broad beans are the most reliable in Britain, sow in autumn or spring, and are among the easiest.
- Peas for drying are a traditional staple and were the original mushy pea.
- Eggs are the efficient answer. A few hens convert kitchen scraps and forage into a daily protein supply with far less land than any plant protein. See keeping chickens in this domain.
- Rabbits, on a small scale, convert greens into meat in a very small area.
- Fish and foraged protein, subject to the law. See fishing in this domain.
Combine sources. Beans plus grain plus eggs covers protein adequately, and a garden alone does not.
Fat, which is the real gap
The nutrient nobody plans for and the one that is hardest to produce.
Britain grows almost nothing that yields useful quantities of fat at a garden scale. Oilseed rape and sunflowers need area and pressing equipment. Nuts take years and yield unpredictably.
Which means:
- Store cooking oil, and rotate it. It is calorie dense, it is cheap now, and it cannot be made.
- Animal fat is the realistic home source. See rendering fat, which is also the input for soap and for candles.
- Nut trees are worth planting anyway, because they take years and the best time to start is now. Hazel and walnut both do well in Britain.
Fat matters more than it sounds in a cold winter on stored food: it carries calories in the smallest volume, and a diet of root vegetables and greens with no fat is unsatisfying and hard to eat enough of.
Storage is half the value
A crop you cannot keep is a crop you eat in a fortnight.
The value of potatoes, onions, squash, beans and root vegetables is not only what they yield but that they store with no equipment, no power and no processing.
- Potatoes: months in the dark, cool and frost free. See root cellaring.
- Onions and garlic: months, dry and airy, once properly cured.
- Winter squash: months, in a warm dry room, and they improve.
- Dried beans: years.
- Roots in the ground or in sand: through winter.
- Kale, leeks, sprouts and chard: stand in the ground and are picked as needed, which is a form of storage.
Plan the year around what will still be there in February, not around what is ready in August. August feeds itself.
What to do with a small garden
Given the arithmetic, the sensible priorities for limited space.
- Potatoes, if you have any real area. Best return, easy, and they store.
- Things that stand through winter: kale, leeks, chard, sprouting broccoli. They fill the hungry gap from February to May, which is when a household on stores actually needs fresh food.
- Onions and garlic, which take little space and store for months.
- Something that stores: squash if you have room, beans for drying if you do not.
- Fast salad crops in gaps and containers, for vitamins and morale.
- Herbs, for almost no space, and they transform stored food.
Do not grow what is cheap and abundant while shops work. Grow what is expensive, what does not travel, and what stores.
And put the effort into soil rather than area. A small well-fed bed outproduces a large neglected one, every time. See soil and compost.
What a garden is genuinely for
Having done the arithmetic honestly, the case for growing is still strong. It is just a different case.
- The hungry gap. February to May is when stores are lowest and nothing is ready, and a few winter brassicas and some stored roots make a real difference exactly then.
- Vitamins and freshness, which stored food is poor at and which matter for health over months.
- Extending stores. Every meal from the garden is a meal not taken from the cupboard.
- Skill and infrastructure. Soil, seed, tools and knowledge take years to build and cannot be acquired quickly. A garden started now is a capability in three years.
- Morale. Genuinely, and it is not a soft benefit. Fresh food, work with an outcome, and something growing all matter over a long difficult period.
- Seed, and the ability to keep going. See seed saving in this domain.
The honest summary: a garden is not a food supply. It is the thing that makes a food supply last longer, taste better and be more nutritious, and it is the beginning of a capability that takes years to build. Both of those are worth the ground.