EDIBLE CANNA IN WAIMEA DISTRICT OP HAWAII 
25 
Table 11. — Effect of time and number of applications of fertilizer on yield of 
edible canna 
Plat 
No. 
Number 
of appli- 
cations 
1 
Control. 
1 
1 
Control. 
2 
3 
Time of application 
At time of planting... 
Three months after planting 
Six months after planting 
Three and six months after planting 
At time of planting, and three and six months after planting 
Gross 
Net yield 
yield of 
of root- 
rootstocks 
stocks 
per acre 
per acre 
Tons 
Torts 
42.0 
37.7 
40.7 
36. 6 
41.9 
37. 5 
42.1 
37.7 
41.3 
37. 
43.2 
43.6 
3<J. 1 
Although the response to fertilizer was slight, the fertilized plats 
made higher yields than the unfertilized (control) plats in all cases. 
Plat No. 7 gave the greatest increase in yield, 2.1 tons per acre. 
Weighings of individual hills showed no differences in average size of 
rootstocks in the fertilized and unfertilized plats. The value of the 
increment of 2.1 tons at $3.50 per ton is only $7.35, whereas the 
fertilizer applied cost $33. These data, while very fragmentary, 
would seem to indicate that on the rich and almost virgin soils of 
the best lands of the district, immediate fertilization is not necessary. 
However, analyses given in another part of this bulletin show that 
a crop of canna rootstocks removes the equivalent of 1,200 pounds 
of high-grade fertilizer from the soil. This heavy drain must event- 
ually be met by equivalent returns of fertilizer. On the poorer lands 
of the district it is probable that an immediate response to fertilizer 
can be had. 
TIME OF HARVESTING 
The best age at which to harvest the canna crop is a much-disputed 
question. Since in Hawaii canna grows continuously though irregu- 
larly, it can not be definitely stated when the crop is mature. In 
Queensland, where growth is checked by cool weather and frosts 
during the winter, the crop is harvested at 10 months of age, or when 
the rootstocks " indicate their maturity by the triangular slit in the 
outer scale leaf of the bulb assuming a purple color." 3 However, it 
is further stated that the crop may be held over during the winter 
for a second season's growth. These observations do not seem to 
apply to Waimea where the climate is rather uniform. 
To determine the monthly increments of growth, two 1-acre plats 
were planted with edible canna, one receiving seed at the rate of 
one per hill and the other at the rate of two per hill. The resulting 
crop was harvested from 0.1 -acre areas in each plat every month, 
beginning with the ninth after planting and continuing through the 
twentieth month. 
The following notes made from time to time show distinct differences 
in the growth of the crop : 
February 12, 1925: Whole field growing vigorously. First blooms appearing 
and stalks 8 to 10 feet high. Many large spikes evident. 
April 16: Last two months have been cold and wet. Vigorous growth of 
February apparently checked. Many spike rootstocks apparent with a large 
proportion of spikes dead, as is indicated by discoloration at apex of rootstock. 
» Personal correspondence from H. C Quodling, Director of Agriculture, Department of Agriculture 
and Stock, Brisbane, Queensland. 
