36 BULLETIN 415, U. S. DEPARTMENT OF AGRICULTUEE. 
SEASON, 
Planting. 
The chief factor governing the choice of the planting season is the 
climate, and this principally in its relation to the soil moisture at 
the period of and for a time following the planting operations. 
Lack of sufficient soil moisture during the period closely following 
planting and before the stock becomes well established is responsible 
for a large proportion of the mortality which occurs in plantations 
on the National Forests. This is particularh^ true for species natural 
to the region and normally hardy on similar sites. AYhen planting 
operations are extensive, it is often necessary to conduct them during 
both fall and spring because the period suitable for planting is not 
long enough in either season for their completion. 
SPEING PLANTING. 
Where sufficient rainfall occurs during the spring and early sum- 
mer months, the spring is almost unquestionabl}^ the logical time for 
conducting planting operations. The soil is in good condition: the 
planting operations will not normally be hindered for any great 
length of time b}" newly fallen snow : the plants will be in no danger 
of heaving or winter killing; and they will have a considerable 
period in which to become partially established before the advent 
of hot, dry weather. On the other hand, the stock for planting may 
have started growth in the nursery before the planting site is in a 
condition to receive it ; and labor is more difficult to obtain than at 
other seasons of the year. 
SUMMER PLANTING. 
Summer is the rainy season in some parts of the country, and as 
the soil is in the best condition for the growth of plants it might be 
thought that this would be a favorable time for field planting. Up 
to the present, however, summer planting has been found to have 
few points which make it commendable. Under normal conditions 
trees are in an active growing state during the summer, and the 
field planting of growing stock is almost certain to meet with failure. 
It would seem that stock held in cold storage or held back in the 
nursery by mulching might be planted successfully, but such plant- 
ings with western yellow pine in Arizona and New Mexico have been 
unsuccessful on the whole. The trees have usuall}^ died during the 
following fall and winter. Field planting of potted trees during 
the summer has been partially successful with 1^-0 ^ western yellow 
1 The first figure indicates the number of years plants remain in seed beds ; the second 
figure, the number of years in transplant beds. 
