SOWING AND PLANTING SEASON FOR WESTERN 
YELLOW PINE 1 
By W. G. Wahlenberg 
Forest Examiner , Priest River Forest Experiment Station } United States Forest 
Service 
INTRODUCTION 
In experiments with the western 
yellow pine ( Pinus ponderosa) at the 
Savenac Nursery at Haugan, Mont., 
many helpful things have been learned, 
although it may now be seen that the 
first years of experimentation were 
not as effective as they might have 
been. The problem was attacked in 
much the same way as that of the 
western white pine ( Pinus monticola), 
because at that time there was no 
means of knowing that the western 
yellow pine has no such decided prefer¬ 
ence for one season of sowing over 
another as is the case with the western 
white pine. For at least two seasons 
sowings were made in the fall and the 
next spring, with the purpose of watch¬ 
ing developments of the following 
season and comparing the results of 
the fall and spring sowings. These 
comparisons were carefully made and 
they indicated advantages for both 
sowing seasons. Later, when several 
sowing dates in the fall were compared, 
it became evident that the time of 
owing within the fall or spring season 
ss a larger factor than season itself, 
ilt was realized that efforts should 
first be directed toward the determina¬ 
tion of the optimum time to sow 
within each season, and that these 
dates could then be used for com¬ 
parisons between seasons. 2 
EARLY COMPARISONS OF SPRING 
AND FALL SOWINGS 
Plots of western yellow pine were 
sown on September 15, 1913, and on 
May 1, 1914, and observed during 
1914. The germination from fall-sown 
seeds started in the middle of April 
and was 98 per cent complete before 
May 18, while the spring-sown seeds 
had not sprouted a single individual 
by that date. The plants resulting 
from the fall sowing were also better 
developed in most respects than those 
from the spring sowing. They 
were slightly more top-heavy, however, 
the ratio of tops to roots by weight 
being 4 per cent larger. Weights of 
100 and measurements of 200 plants 
were taken. From these figures it 
appears that promptness of germina¬ 
tion and superior development of the 
plants are results of fall sowing. (See 
Table I.) 
On October 23, 1915, two beds were 
sown with 8,000 seeds each, and on 
May 6, 1916, a similar pair of beds 
was sown in the same way. The 
spring-sown beds led in germination 
by nearly 50 per cent and in survival 
at the end of the season by 12 per cent. 
In top-root ratio by weight the fall- 
sown were more top-heavy by 8 per 
cent. However, the value of this 
comparison must be discounted be¬ 
cause of the later finding that good 
results can not be expected from sowing 
so late in the fall. 
The hold-over tendency of seed, so 
important with western white pine, 
deserves mention in connection with 
the western yellow pine. In most 
cases with fall sowing the hold-over 
germinations are entirely absent, al¬ 
though 0.2 per cent of hold over has 
been noted. With spring sowings the 
tendency is greater. Although it is 
usually less than 1 per cent, it may 
amount to more than 25 per cent 
under certain conditions. The 28 per 
cent hold over which resulted from 
a sowing on May 21, 1919, has been 
attributed to the extremely dry spring 
that year. (See Table III.) 
1 Received for publication May 22, 1924; Issued April, 1925. . 
1 The early field work for these experiments was conducted by E. C. Rogers, assisted by P. C. Kitchm. 
Their manuscript progress reports cover the earlier experiments cited. 
Journal of Agricultural Research. 
Washington, D. C. 
( 245 ) 
Vol. XXX, No. 3 
Feb. 1, 1925 
Key No. F-16 
