60 BULLETIN 24, U. S. DEPARTMENT OF AGRICULTURE. 
TIME TO+PLANT. 
Spring planting is reeommended. In the Northern States, in par- 
ticular, fall or winter planting is hkely to meet with poor success. 
The alternate freezing and thawing of the ground during the winter 
will often lift the plants entirely out of the ground. This applies 
equally to cuttings and seedlings. On light, sandy soil, however, 
this danger is comparatively small. In the south of the valley the 
danger of frost heaving is slight, and if planting is not done on 
very heavy soils there are advantages in planting during late 
fall or winter. Seedlings planted early in the fall will recover 
from any root injuries and become well established before spring. 
In fact, stock planted early in the fall will continue root activity 
well into the winter, and therefore will begin growth early in the 
spring. This will enable it to withstand better the spring overflow, | 
which in the South is apt to occur within 4 or 5 weeks after vegeta- 
tion begins. Furthermore, autumn planting is better in localities 
subject to prolonged drought in the spring. In general, however, 
fall planting, at least for the present, should be restricted to rooted 
stock, as it is still uncertain how well plain cuttings would withstand 
long exposure throughout the winter and overflow in late spring. 
PURE VERSUS MIXED PLANTING. 
Cottonwood may be planted either pure or in mixture with other 
species. An advantage of pure plantations consists in the greater 
simplicity of field planting and its consequent lower cost, especially 
since cottonwood stock is usually cheaper than that of any other hard- 
wood tree that might be used in mixture with it. Pure plantations 
yield a larger quantity of solid wood on a short rotation. 
The advantages which may possibly result from mixed planta- 
tions are a possible increase in the board-foot yield; an improvement 
in the quality of the timber, due to clearing cottonwood of its 
branches; and in shading the ground. Mixed planting is particu- 
larly of advantage in the establishment of windbreaks, for which 
cottonwood, as it matures, becomes too open to be thoroughly effective. 
The associate species ordinarily would have no value, except pos- 
sibly for cordwood. It would act chiefly as a “ filler” to improve 
the quantity or quality of the cottonwood. Any of the following 
species would make suitable fillers: Silver maple (Acer saccharinum 
Linn.), boxelder (Acer negundo Linn.), sycamore (Platanus occi- 
dentalis Linn.), white ash (Praxinus americana Linn.), and green 
ash (Fraxinus pennsylvanica Marsh). Probably the silver maple 
will be the most suitable species. One-year-old maple seedlings can 
be purchased from dealers for $2 to $3 a thousand. If a filler is 
