THE ORCHID WORLD. 
133 
THE ART OF SHADING ORCHIDS. 
By J. M. BLACK. 
THE art of shading Orchids is to obtain 
the requisite amount of heat and Hght 
from the sun during the spring, sum- 
mer and autumn ; and in the spring this will 
mean the greatest amount of heat and light 
compatible with safety ; but though the influ- 
ence of a sufficiency of light is so great, still 
it will be better to err on the side of too much 
rather than too little shade. We shade Orchids 
not because the sun in these islands is stronger 
than the sun they receive in the regions where 
they grow wild, but because, being under glass, 
the air in which they grow is bottled up and 
becomes superheated. With abundance of 
air in a house much more sunlight will be 
endured by Orchids, but it is not always advis- 
able to give a big quantity of air. If the wind 
is keen and sharp, with a bite of frost in it, 
such as we frequently get from the east and 
north-east in late spring, to keep the blinds 
up and open wide the ventilators might pre- 
vent direct injury from the sun, but the wind 
and the sun together would create a condition 
of affairs inside that would act injuriously on 
the plants, just as a cold, blighting east wind 
and sun act injuriously on outside vegetation. 
After a long, dull space, when we feel greedy 
after light, we are frequently tempted to take 
some risk, but it is a mistake. 
Plants that are well established will endure 
and benefit by much more sunlight than plants 
that are not, and, as potting operations are 
carried on more or less during all the sunny 
season, much circumspection must be used so 
that freshly-potted plants do not suffer. A 
plant that is well established quickly replaces 
the moisture that is transpired from the 
leaves, and light and air on this plant will act 
as an incentive to root action as more call is 
made on the roots for moisture. Air and light 
on this plant will have a beneficial effect, build- 
ing up strong, sun-resisting foliage and strong 
root action ; but take the case of the same 
plant when re-potted and presumably broken 
up, an operation that disorganises the balance 
between the foliage and the roots ; root-caps 
will be broken, roots torn, and the work which 
they previously performed with ease will now 
become difficult. Leaf transpiration will be 
the same, and, if we continue to give this plant 
as much light and air as it previously endured 
with benefit, we are sure to cause it injury, 
probably irreparable. The roots being unable, 
through the disturbance and laceration in- 
separable from re-potting, to rapidly enough 
replace the moisture transpired through the 
stomata, the reserve in the pseudo-bulb will 
be drawn upon, which, with the leaf, will 
shrivel. At this period, therefore, instead of 
giving the plant the light and air which it 
would in a normal condition enjoy, close shade 
and less air will be necessary for a time, and 
to check transpiration the plant should be 
more frequently sprayed, and careful watering" 
at the root must also take place during the 
re-establishing period. We thus find that 
airing and shading are interdependent, and 
whether much or little should or may be given 
will always have to be regulated by the con- 
dition of the plants at the particular time. 
Seedling Cattleyas and Lselias that are half- 
grown and in a good, healthy condition will 
endure more sunlight than imported Cattleyas. 
The reason for this mav be found in the fact 
that each of these little leafy bulbs is ampl\- 
provided with roots, whereas adult plants with 
many bulbs rely nearly always on the leading 
two or three bulbs of the rhizome for susten- 
ance, so that the back bulbs and leaves turn 
yellow quickly if over-sunned. In nature 
Cattleyas and Laelias do not lose their roots 
m this way. An examination of imported 
clumps will disclose green roots far back on 
the rhizome, and we know that the roots 
ramble far and wide, so that it is hopeless for 
us to copy nature too closely in this matter of 
light and air (for in nature no re-potting is 
done), and we must also forego many other 
liberties that nature may take. And this 
brings us to another question : Good cultiva- 
tion does not imply that we should give 
Orchids all the light and air that they will 
endure without apparent injury. Light and 
air, while solidifying and ripening, have also 
