Dec] the GREEN-HOUSE. 539 
carefully every night, and also in extremly rigorous frosts except 
while the sun shines on the windows. 
When Green Houses are so constructed as to have no window- 
shutters, which is certainly wrong, large thick mats should be 
hung and nailed, or made fast by small hooks, in front of the lights 
every cold night, and also in the day time when the weather is 
very severe, and no sun. It may sometimes be necessary, even 
when there are shutters, to hang and nail up mats in front of the 
windows, to check the piercing wind. If there are short roof-lights, 
they must be covered with mats, or with strong canvas during the 
continuance of severe weather; these n^ay be so contrived as to roll 
up and fall down, by nieanu of lines and pullies, at pleasure. 
During t'.c continuance of severe frost accomfia?iisd by piercing 
cuttirg nvincU^ ;.he windows must never be opened, that is, you must 
neither slide the lights up or down, but always keep them and the 
door or doors close, and any plan'.s that are too near the glsss must 
be removed into the interior of the house, especially at night and in 
cloudy dark weather. 
If you find the frost likely to I'each your plants, notwithstanding 
all this care, you must heat the flues by gentle fires at night, and 
also in the day time when the frost is very piercing and the wea- 
ther dark, and indeed without such a convenience it is almost use- 
less to attempt the erection or trouble of a Green-House either in 
the middle or eastern states, on account of their extremely rigorous 
winters. But you must be particular never to heat the air above 
40 or 45 degrees, of Fahrenheit's thermometer; for all the heat that 
the plants require at this season, is only just as much as will pre- 
serve them effectually from frost. 
However, be very particular every day when the weather is 
mild and the sun shining on the windows, to slide down the sashes 
even if but half an hour, in the middle of the day, to admit fresh 
air and ventilate the house; for if the plants are kept too close they 
will become tender and weak, and besides, it will cause the leaves 
of some kinds to turn of a yellowish sickly colour, and after to get 
mouldy and drop off. 
N. B. The plants must never be deprived of light by keeping the 
shutters close, a moment longer than it is found absolutely neces- 
sary for their preservation; and though I am not an advocate for 
much fire-heat in a Green-House, yet I would prefer it to keeping 
the plants too long in darkness, which has an extremely bad effect 
upon them. 
For particulars respecting watering and other information, I 
would recommend to your perusal at this term, the entire of the 
article Green-House, in January, and also in February, pages 86 
and 166; the general care during each of these months is nearly 
the same. 
The plants which you are wintering in garden-frames, must now 
be carefully attended, agreeably to the directions given in page 571. 
