Unless you are an obsessive plantsman, or want to spend every waking minute in an intimate relationship with the soil — and if you are, you would not have needed this blog in the first place — there is no need to feel deprived if you have, or intend to have, a home with no garden in the accepted sense.
As living space in the twentieth century has become increasingly at a premium, many kinds of property now have no real gardens. However, just about everyone has some form of outdoor place where plants of one type or another may be grown quite successfully. In any case, far better to be able to indulge what little growing space you have than to be overwhelmed with a large neglected garden that you have not time, strength, money and/or inclination to care for properly.
The ideas suggested here for no-garden gardens can equally apply to patios and paved areas, walls and window-ledges, even if you have a conventional garden as well.
Flats, flatlets and maisonettes
Many of these have some area of garden in the vicinity allocated to each resident, but there are a lot more which do not. Often there is a balcony attached to the flat, though, and some enterprising developers may have even included a planting area in the top of the wall surrounding this. Otherwise the floor area can accommodate a wide variety of plants in tubs and other containers and the wall inside the balcony could have hanging pots and baskets on it. If there is no balcony, the window-ledge is usually wide enough to take some kind of trough, or the area immediately under it could have a window box attached to the wall where it is accessible by leaning out of the window. (But do be careful! This activity is only for the comparatively young and fit.)
Do ensure before you embark on this enterprise that there are no restrictions on growing plants on the walls written into the deeds, or the agreement with the landlord, if you are a tenant. Owners of rented accommodation often do not like their tenants interfering with the structure of the property by drilling the wall for hooks, brackets, trellis, etc., so regulations relating to this must be firmly investigated before you start.
Assuming there is nothing standing in your way, it is then up to you to make sure that anything that you do put on the wall which overhangs the street or area accessible to other residents or the general public is more than firmly attached, bearing in mind the amount of buffeting it is likely to receive if the flat or whatever is at first-floor height or above. Very high flats receive tremendous amounts of wind, and what would be normal at ground level becomes more and more of a howling gale the higher up you go. Pots, boxes, baskets, etc. becoming detached and falling off could at the least make you very unpopular or land you in court, and at the worst they could kill someone.
The wind factor greatly affects the type of plant suitable for high-rise gardening, of which more anon, but do not let this put you off, because there are still plenty of things you can grow successfully.