The experts always tell you to put a "crock" (usually a piece of old broken clay pot) in the bottom of a small pot and perhaps an inch or so of crocks in the bottom of a large/very large pot in order to promote drainage. Just think about it for one moment. In a large pot - 12 or 15 inch perhaps, why is it that the water can pass 11 or 14 inches down the compost or soil, but not manage the last inch. I think the reason for putting crocks in the bottom was something entirely different.
In the days of terracotta (clay) pots the drainage hole in the bottom was single and quite large, especially when compared to the half dozen or so smaller holes found in the modem plastic pot. This large hole would easily let the excess water out, but more to the point it would also allow the compost or soil to run out, so the crocks were there to prevent the latter from happening. Pieces of old broken pot were used because not only was this a way of making use of what would otherwise have been a useless (expensive) item, but also because these fragments were curved and thus less likely to block the hole to the passage of water; a flat crock across the hole could quite easily impede the free drainage of excess water. Using today's ubiquitous plastic pots one seldom puts a crock in the bottom of any pot below about 8 inches in size. Above this size and particularly when one gets to the big, deep planters of 15 or 18 inches, there is a good reason for putting "crocks" in the bottom, by doing so one reduces the amount of compost needed, and crocking material is usually much less expensive than compost - indeed often free - and in such a large container one seldom needs more than about 10 inches or so of compost for the root system of the fuchsias planted therein.
The nature of the crocking material can vary depending on availability, as well as the type of plant in the container. With large containers, weight can be a problem, especially if they have to be moved from place to place (for over-wintering in a frost free place, for instance), in which case two or three inches (or more) of broken up pieces of expanded polystyrene will solve both problems. On the other hand, if the plant growing in the container is tall, a half or full standard for instance, then extra weight in the bottom of the contalner will help to prevent it from being blown over in strong winds; in this case one would use large stones, broken bricks and similar material.
It is with these large plastic containers, often with flat, bottoms that drainage can really become a problem, even if they do have a large number of drainage holes in the bottom. If they are standing on smooth concrete or very compacted earth, the very weight of the compost can seal the bottom of the container to the underlying material making egress of water virtually impossible. In such cases it is imperative that the containers have drainage holes m the sides near the base, where they cannot possibly get blocked. If the container does not already possess such holes, then drilling six to eight holes about a quarter of an inch in diameter around the sides about half an inch up from the base should be unobtrusive but adequate to ensure the health and safety of your valuable plants, fuchsias or otherwise.       

Courtesy of the BFS CAD's Fuchsia News

Proofreader's P.S. "Did you know that traditionally the correct way to crock a pot was to use only pieces of the same size pot as was being crocked (i.e. a broken 7" pot to crocka 7" pot) crocks being built up in layers concave side down, usually 3 layers, sometimes 4 in very large pots. This was partly to stop the compost coming out of the drainage hole but also to aid drainage."

The following cultivars have now been added to the British Fuchsia Society Hardy List: Annabel, Beacon Rosa, Barbara, Celia Smedley, Diana Wright, Foxgrove Wood, Heidi Ann, Logans Wood, Plenty and Scarcity.
The BFS 2002 Hardy List (a full copy appears in our Show Schedule) replaces all previous lists. It is for show purposes only. It does not necessarily mean that the fuchsias listed will survive, when left in the ground, through every winter, in every corner of the United Kingdom.
Note: Any cultivar suggested for the Hardy List must have survived at least five consecutive winters and begun to flower in July or early August.