24 BULLETIN 57, HAWAII EXPERIMENT STATION 
1 to 1 3^2 tons per acre, the cost of seed selection is doubled per acre, 
and the cost of planting is increased. For these reasons, planting 
three and four seed to the hill is hardly to be commended where the 
crop is grown on a large scale. 
SPACING AND MULCHING WITH CANNA TOPS 
In an experiment made to learn the effect of spacing on yields, 
edible canna plantings were made on 0.1-acre plats at distances of 
2 by 4 feet, 3 by 4 feet, 4 by 4 feet, and 3 by 3 feet. Weeds encroached 
upon the zone of the resulting crop to such an extent as to render 
results unreliable. However, the present practice of planting at 
distances of 4 by 4 feet seems to be desirable for Waimea conditions. 
It permits cultivation during the first six months' growth of the crop. 
After this time weed growth is held in check by the luxuriant foliage 
which shades the ground. Planting at distances of 4 by 4 feet also 
permits cross cultivation, which is of considerable importance in 
eliminating hoeing. 
The experiment made to learn the efficacy of mulching with edible 
canna tops was conducted on four 0.1-acre plats. The rows were 
top-dressed immediately after planting with a heavy and a light 
mulch of fresh, green tops and with partly dried tops. Mulching 
was expected to prevent weed growth in the row and also allow 
cultivation between the rows. All plats gave depressed yields. 
Mulching caused the seed to rot, depressed the rate and percentage 
of germination, and had little effect in reducing weed growth in the 
row. Part of the mulch remained green for some time, and this 
mulch and the weed growth acted as hosts for cutworms, which 
attacked the canna stalks. Mulching with canna tops apparently 
offers no advantage for the crop in the Waimea district. 
FERTILIZERS 
Observations on the growth of edible canna show that during the 
first three months after planting the crop grows very slowly and 
produces only one or two plants. It develops much more rapidly 
during the next three months and at the end of six months bears 
many vigorous stalks and a profusion of buds which are ready to 
develop. For these reasons fertilizer was thought to be more effi- 
cacious if applied to the crop a few months after planting rather than 
at the time of planting. It was thought also that a number of small 
applications would produce better results than one large application. 
At the central station in Honolulu a fertilizer containing consider- 
able amounts of nitrogen greatly increased top growth but did not mate- 
rially increase yield. In the Waimea district mill-run seed was planted 
at distances of 4 by 4 feet on 0.1-acre plats, each of which was given 
a total of 100 pounds of fertilizer. The basal formula was nitrogen 
(N) 5 per cent (as ammonium sulphate), phosphoric acid (P 2 5 ) 8 per 
cent (as superphosphate), and potash (K 2 0) 10 per cent (as potas- 
sium sulphate). The field was harvested at 20 months. Table 11 
gives the result of the experiment. 
