That are in pots, should be placed in the frame intended for their abode
during winter. If the pots are plunged to the rims in tan, half decayed
leaves, or saw dust, it will greatly protect their roots from the severe
effects of frost. Where glass is used for these frames, they should have
besides a covering of boards, or straw mats; those that are in beds may
be covered as above directed for Primroses, &c.
They ought not to be uncovered while in a frozen state. It is not
altogether the intensity of cold that destroys these plants so much as
the alternate thawing and freezing.
All half hardy plants, such as _Wall-flower_, _German stocks_,
_Sweet-bay_, tender roses, with several others, should be protected as
above directed for Carnations. Earth or tan should be put round the
outside of these frames, which will be a partial shelter from the
changing state of the atmosphere. Oak leaves answer the purpose very
well, but they are a harbour for all kinds of vermin, especially rats
and mice, which would destroy every thing. It may be useful to say a few
words on the nature of tan or tanner's bark. Many suppose that the
smallest quantity will produce heat, If three or four cart loads of it
are put into one heap, and protected from the rain, it will ferment; and
when the first fermentation is abated, by mixing it with leaves, a
substantial hot-bed may be made. Or put it by itself into a pit, and
where there is no pit, boards may be substituted to keep it together;
either of these methods will produce a lasting heat. But in small
quantities and exposed to rain, &c. no heat will be produced, but rather
the contrary. It is excellent when dry in keeping out frost from any
plants, being a body not easily penetrated, similar to dry sand,
saw-dust, or dry leaves. Frequently the same opinion is held in regard
to stable manure, small portions of which will never produce heat.