16 Colorado Agricultural College 
tice of high hilling has grown out of the conception 
that the potatoes should not come into direct contact with irrigation 
water, but that the water should be applied from below, and thence 
move upward into the soil by capillarity. .One might argue that 
it makes no difference whether the tubers get moisture from below 
or from the side, so long as they are not in contact with the free 
water. 
The writer is inclined to believe that less hilling or lower ridges; 
is preferable to the high ones, as high ridges invariably raise the 
soil temperature around the tubers to several degrees above that of 
level soil, thus creating a condition that is not the most favorable 
for the normal development of the plant. This is especially true 
of the Eastern Slope where the summer days are hot and the soil 
temperature becomes correspondingly high In the mountain sec¬ 
tions, the grower does not hill his potatoes to the extent done on the 
Eastern Slope, yet no one would question that the results obtained 
by those growers are less satisfactory than those obtained on the 
Eastern Slope. 
In the Greeley section, high hilling is almost universally prac¬ 
ticed, and is looked upon as essential to success. While high hilling 
may be successful during certain seasons, it is also true that during 
a warm, dry season, lower ridges would tend to keep the soil tem¬ 
perature lower and thus furnish better conditions for the potato 
plant. 
IRRIGATION 
The Horticultural Department is frequently called upon to 
give advice as to when and how potatoes should be irrigated. To 
answer such questions intelligently, a knowledge of soil conditions 
is absolutely necessary. Many growers believe that potatoes should 
not be irrigated until the vines are setting the tubers, even tho' the 
vines are actually suffering from lack of water. This may work 
out all right, but one may well question the wisdom of following 
such a rule. It is universally the rule that when a growing plant 
needs water and shows signs of wilting, water should be applied, so 
that the normal growth will not be checked. When the tubers have 
once set, it is necessary to irrigate so as to keep the soil in best 
growing condition possible for the balance of the season, or until 
the crop is matured. In other words, there should be no check to 
the growth of the plants after the tubers have once started to 
develop. If a check is given during this period and the plant re¬ 
sumes its growth afterwards, knobby and gnarly tubers result. 
Hence the importance of keeping the young potatoes growing with¬ 
out check thru out the period. 
