Temperature is an important factor in the successful cultiva- 
tion of plants, and violent fluctuations should be avoided as far as 
possible. If warmth-loving; plants are grown in a room which is 
unheated at night, as often happens, they should be protected in 
some way during severe weather. This may be done by removing 
them to a heated room or away from the windows. If this is 
impossible, they can be protected by covering them at night with 
paper or other non-conducting material. Bound up with the 
question of temperature is that of ventilation. Plants object to 
impure air as much, or more, than human beings ; therefore, the 
room in which they are grown should be ventilated whenever 
possible, taking care, however, that cold drafts do not blow 
directly on the plants. 
One is frequently asked, “How often must I water my plants?’’ 
To this one is compelled to reply, “As often as they need it.’’ 
There can be no fixed rule as to the quantity and frequency of 
the application of water to plants; so much depends upon the 
humidity of the room in which the plants are growing, the nature 
of the plant, and the capacity of its roots to absorb water. 
Whenever watering is done it should be done thoroughly, so that 
the earth is wet all through. No further watering is needed until 
the earth shows signs of drying out, when another application 
should be given. Thorough watering is most important, other- 
wise the earth on the surface of the pot may have the appearance 
of being moist, while an inch or so below the surface it may be 
dust dry, greatly to the detriment of the plant. 
Those living in a city often have difficulty in obtaining a 
supply of suitable soil for potting purposes, and the best plan in 
such cases is to obtain soil read}' mixed from a florist. The best 
kind of soil for the majority of house plants is that formed of 
loam cut from the surface of a meadow, pasture or lawn. This 
should be mixed with stable manure in the proportion of three 
parts of soil to one part of manure, piled in a heap, and left for a 
year or so in order that the grass roots and manure may decay. 
Using this as a base, by the addition of leaf mould, peat, or sand, 
for such plants as need it, we have a soil that makes a suitable 
potting medium for almost any class of plants. 
No definite rule can be laid down as to when plants should be 
repotted. If they are making vigorous root growth this maybe 
done at almost any time, but, as a general rule, repotting is best 
done in early spring, just before the plants begin their new 
growth. Repotting into a larger pot should only be done when 
the pot is crowded with roots, otherwise harm rather than good 
will result ; indeed much of the unhealthiness in house plants can 
be traced directly to attempting to grow them in too large a pot. 
It sometimes happens that repotting is necessary because there 
are too few roots in the pot rather than too many. This occurs 
when, through overwatering, the earth becomes sour, and, as a 
