DRAINAGE HOLES
All minigardens, particularly those in which alpines are to be
grown, need very good drainage. It is therefore important to
ensure that surplus water can and does drain away efficiently
and is not allowed to stagnate. A trough (similar to a sink) can
function efficiently with a single fairly large drain hole where the
floor of the sink slopes towards the hole. An excellent plan is to
build up the bottom in the centre to have a gentle slope downward to two drainage holes (as emphasized in Fig. 26), set in
little gulleys. For shallower troughs, and often for window-boxes,
a number of sufficiently large drainage holes can be made. In
cases where the trough stands on a solid ground it should be
raised slightly to permit the surplus water to escape freely; where
appropriate a shallow drainage tray can be provided.
Allow for the actual holes before the concrete is placed in the
bottom of the mould. A tapered wooden bung or "cork" is made
for each hole to the size required, and placed into position before
the concrete is added. When the concrete has set, the taper
allows the bung to be knocked out easily.
"CURING" THE CONCRETE
The long-sustained notion that alpines do not take kindly to
concrete has been proved a fallacy, but nevertheless it is advisable for the concrete to become seasoned or "cured". This is
simple. Soak the completed trough in a strong solution of
permanganate of potash for two or three days. Sufficient crystals
should be diluted in water to make it a dark pink in colour.
Follow this with a thorough washing in clean water and then
leave out in the open for several days.
If you have no container large enough in which to soak the
concrete trough, place the plug(s) in position and fill the actual
trough to the brim, first with the solution and subsequently with,
the water.
Old sinks of various kinds are admirable for outdoor minigardens providing that they are not of the glazed variety. The
old-fashioned stone sinks are the best of all but are comparatively
rare; they are usually rather heavy and should therefore be
placed in their permanent position and planted accordingly (with
hardy plants).
FITTING WINDOW-BOXES
Some of the methods for fitting and fastening window-boxes
are shown in Figs. 14 to 20. It is usually necessary to raise the
base of the trough at the front to (a) counteract the slope of the
sill and permit the garden to lie level, and (b) where necessary,
to raise the garden to a level to ensure maximum visibility from
the inside of the room. Rubber doorstops or something similar can be used, but properly cut and fitted wedges are recommended.
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