[telegraph.hill]

How much land would the average family need in order to practise self sufficiency?

I suppose it depends on the degree to which you practise it. You would at least need sufficient land to grow your own vegetables and keep a few animals.

[flaja]

It would depend greatly on your climate and the quality of your land (soil fertility, availability of water et cetera).

My grandmother (born in the early 1920s) grew up on her family's 69 acre dairy/poultry farm in North Carolina. The family had 6 people total, although the oldest children were almost adults before the last child was born. Everything they ate came from the farm and they still had enough milk and chicken left over to sell. The farm must have been very profitable (and the whole family is full of tightwads). My grandmother's youngest sibling still has 39 of the original acres (the rest was divided when my great-grandfather died in 1952). When my great-grandmother died last year she left enough cash for her grandchildren to get some of it.

But, here in Florida we have poor soil and poorer soil. We also have every kind of bug, mildew, rot and mold imaginable. And any farm can easily grow a bumper crop of weeds. NC and Fl both get about the same amount of rain. But in NC you get a little rain about every 3 days. In Florida you may get no rain for 3 months and then have it rain every day for a month. With our soil, climate and growing conditions I doubt that anyone could grow enough food and enough variety of foods to be completely self-sufficient here.

[cats3]

I suppose it depends on how carefully one can use a tiny amount of space and practice appropriate agricultural techniques such as crop rotation so that nutrients are not continually used up in the soil and not replaced.

My mother used to say that a "weed" is only a plant growing where you don't want it. I think of dandelions as weeds but many people eat dandelion greens. My mother-in-law used to deliberately grow them.

Here in Essex County, New Jersey, USA we have very rocky compacted soil.
It takes practice and observation to understand what grows well here and how to ease the density of the soil so water doesn't "pond" at the surface.

I no longer use peat moss as it is a non-renewable resource.
Sand works well as do wood chips. Shredded paper works well too (although it's not pretty if you can see it) as long as the ink is non-toxic like soy-based ink. Newspaper shreads also work.

[cats3]

As for apartment dwellers, one needs to learn what one can grow in pots, shade/part shade (tomatoes, string beans for example can be grown in pots but they prefer sun. Tomatoes like to drink a lot of water. I dump water unfinished from my glasses in there. It's me eating the tomatoes so no worries about germs from my mouth in the tomatoes).

Is there a balcony or terrace? A public garden? a windowsill? any sunlit space? Another alternative is to use a plant light on a timer.