The practice of sprouting seed potatoes before planting them is gaining ground amongst farmers as well as gardeners. Shallow boxes or baskets of any description may be used for the purpose, but that most generally useful is a wooden box (see fig. 483) about 2 ft. long, 12 in. wide, 3 in. deep, having four corner posts about 7 in. high. A batten is nailed to each of the two end posts, and a cross handlebar 2 ft. long is fixed from one to the other. This enables a man to carry two sprouting boxes at a time.

The object of sprouting the tubers before planting is to induce growth to start from one or two of the best eyes, and thus secure active growth in every case. If the tubers are well exposed to the light, but protected from frost, the sprouts will be slow in growth and sturdy; in the dark they would become pale and long, and would be easily broken off, in addition to which the tubers would also shrivel.

Another advantage of sprouting is that planting may be deferred for a month or more beyond the usual time. This is particularly valuable in the case of early varieties, as they can be kept sprouting indoors instead of running the risk of being killed by the early frosts in the open.

The sprouting boxes referred to cost about 4d. each, and will hold about 20 lb. of seed potatoes. With fair wear and tear they ought to last for several years, and are so constructed that they can be stacked on each other easily either full or empty.

It is better to have only one layer of tubers in a box, although two layers may be admitted when space and boxes are a consideration. The sets should be examined occasionally after sprouting has commenced, and all sprouts except two or three at the top should be removed. In this way the reserve material in the tuber is directed to the best sprouts, and these in turn will form good sturdy stems, from the base and joints of which masses of fibrous roots will penetrate the soil.

Does It Pay To Sprout?

There can now be little doubt of this. Each tuber planted is known beforehand to be in a growing and healthy condition; consequently there is no danger of blank spaces, so often caused by the non-development of some tubers. Each square yard of land produces its fair supply of tubers (if sufficient space has been allotted), so that the maximum results are secured. The following figures, taken from Leaflet 58 of the Irish Department of Agriculture, show at a glance the advantage to be gained by planting sprouted "seed" potatoes: -

Sprouting Box for Seed Potatoes.

Fig. 483. - Sprouting Box for Seed Potatoes.

Table Showing Result Of Sprouted And Non-Sprouted Potato "Seed"

Year.

Number of Centres.

Average Yield per Statute Acre.

Average Gain

Due to

Sprouting.

Sprouted Seed.

Unsprouted Seed.

tons.

cwt.

tons.

cwt.

tons.

cwt.

1903

12

11

1

9

8

1

13

1904

34

11

6

8

13

2

13

1905

91

12

17

10

16

2

1

1906

67

11

9

9

2

2

7

1907

67

10

6

8

6

2

0

1908

67

13

0

10

15

2

5

1909

50

12

19

10

4

2

15

Average of 388 tests ...

12

0

9

15

2

5

Perhaps the only serious argument that can be used against providing boxes for sprouting potatoes is the question of space and light. The boxes themselves, even if they cost 4d. each, are not a very serious item; and as they will last for several years, with care, the cost should be distributed over that period. It is, however, useless going to the expense of boxes unless there is some frostproof place to store them; and not only must the place be frostproof, but it should be also as well lighted as possible. Sprouting seed potatoes in the dark would be sheer waste. Any rough barn, with glass side and top light, would do for the purpose, and by allowing free circulation of the air the temperature would not rise high enough to start premature sprouting. The advantage of plenty of light is that it causes the skin of the tubers to turn green, and thus, it may be presumed, perform a certain amount of work in assimilating carbonic acid gas from the atmosphere by means of the chlorophyll corpuscles in the cells. In this way the tubers remain plump and fresh, and do not shrivel, as they would in darkness: and the sprouts remain short and sturdy, and are not so likely to get broken off at planting time. Tubers exposed in this way also resist the attacks of fungoid diseases better than those kept in the dark.