This section is from the book "Commercial Gardening Vol4", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
A good deal has been written on this subject, the main point being to discover whether it is more economical to plant large, small, cut, or medium-sized tubers. After many experiments and some years of experience in Potato growing, we may say that there is little to be said one way or the other if the "seed" is sound and the cultivation good. Sometimes cut tubers will show a slight increase in yield over whole ones, and vice versa. The same holds good with large and small tubers. Indeed some very fine yields have been obtained from experiments in which only potato peelings and cuttings were used. Generally speaking, however, it will be found economical to plant tubers weighing about 3 oz. each, that is, about the size of a hen's egg. The cost of seed per acre will of course depend upon the distance of planting and the current price. Taking prices at £3 per ton, with furrows at 3 ft. by 3 ft., 3 ft. by 1 1/2 ft., 2 ft. by 2 ft., and 2 ft. by 1 ft., the following costs per acre are obtained for seed potatoes: -
Distance apart between.
Sets per Acre.
Weight per Acre, at 3 oz.
£3 per Ton per Acre.
1 1/2 "
The vast majority of growers use about 1 1/2 tons of seed potatoes to the acre, but they will probably be astonished to find that the results are not in proportion to the cost of seed, labour, manures, etc, and that better. results are to be obtained with a much smaller quantity of seed.
In selecting seed potatoes, experience seems to prove that it is wise to secure immature tubers from a different neighbourhood each year. In other words, it is bad business for a man to plant his own home-saved seed potatoes. At one time there was a general impression that the best seed potatoes came from Scotland. This, however, is by no means the case, as numerous experiments prove that the seed from Ireland is as good as, if not actually more reliable than, the Scottish seed. Irish seed, however, has the reputation at present of not being carefully selected and "rogued". The safest plan would be for English, Irish, and Scottish growers to arrange for an interchange of seed, and thus maintain the vigour of the different stocks by growing them in different soils and climates.