would far exceed anything ever accomplished when they are kept
permanently in pots.

Out-of-doors.--There are some kinds which may be grown out of doors
altogether, if planted on a sunny, sheltered position, on a rockery. The
most successful plan is that followed at Kew, where a collection of the
hardier species is planted in a rockery composed of brick rubble and
stones. During summer the plants are exposed; but when cold weather and
rains come, lights are placed permanently over the rockery, and in this
way it is kept comparatively dry. No fire-heat or protection of any
other kind is used, and the vigorous growth, robust health, and
floriferousness of the several species are proofs of the fitness of the
treatment for this class of plants.

In any garden where a few square yards in a sunny, well-drained position
can be afforded for a raised rockery, the hardy Cactuses may be easily
managed. To make a suitable rockery, proceed as follows: Find a position
against the south wall of a house, greenhouse, or shed, and against this
wall construct a raised rockery of brick rubble, lime rubbish, stones
(soft sandstone, if possible), and fibrous loam. The rockery when
finished should be, say, 4 ft. wide, and reach along the wall as far as
required; the back of the rockery would extend about 2 ft. above the
ground level, and fall towards the front. Fix in the wall, 1 ft. or so
above the rockery, a number of hooks at intervals all along, to hold in
position lights sufficiently long to cover the rockery from the wall to
the front, where they could be supported by short posts driven in the
ground. The lights should be removed during summer to some shed, and
brought out for use on the approach of winter. Treated in this manner,
the following hardy species could not fail to be a success: