Planting density
If the number of sprouts has been established and the number of tubers per sack is known, the seed requirement for a parcel of land can be calculated. The figures in the table are based on a crop with 15 stems per square metre.The basic principle here is that the sizes 28-35 mm, 35-45 mm and 45-55 mm form 2.5, 4 and 5 stems per tuber, respectively.
Number of sprouts & spacing of tubers in the row
The average number of sprouts per tuber gives a good indication of the number of stems that can be expected. The number of stems determines the required spacing of the tubers in the row. Therefore, to be able to determine the correct distance, it is necessary to establish the average number of sprouts developing from the seed tubers.This is best done by counting the number of sprouts on a representative selection of tuber samples taken from the seed lot.
Row spacing
Potatoes can be grown in rows 50-100 cm apart. As a closed canopy at an early stage is conducive to production, it is important to aim at the quickest possible canopy closure when establishing the distance between the rows.The more favourable the growing conditions, the wider the distance between the row can be. A narrow row distance may give a better distribution of stems, but for technical reasons – the opportunity to make good sized ridges to protect the tubers – it is much better to grow potatoes at wider row distances (75-90 cm). In mechanized potatoproduction, row spacing is determined by the standardized setting of the machinery.
Planting depth
The planting depth should be adjusted according to the soil conditions.Under normal growing conditions, the top of the tuber will belevel with the soil surface. As soil in the deeper layers dries out more slowly than surface soil, planting should be deeper in dry conditions. But while dry conditions make deeper planting essential, this is an advantage if temperatures are very high. A greater planting depth will also be important in circumstances in which the potato tuber moth poses a threat. Deep planting is not necessary in moist conditions, as there is no risk that the surface soil will dry out.
Shallow planting is also advantageous in cool conditions. The consequence of greater tuber depth is that a great deal of soil passes through the lifter during mechanical harvesting. Where the soil is heavy, this will be more detrimenta lthan in the case of light soil. Varietal differences also play a role in planting depth variations. This is another reason why growers should be familiar with all the characteristics of their varieties.
Earthing up
In addition to planting depth, the depth of the soil cover also influences the development of the new haulm. When planting, only shallow earthing up is carried out if soil temperature is low or the seed is of inferior quality. A limited soil coverage also promotes a rapid initial development. A deeper soil cover, on the other hand, can be applied when temperatures are high and the seed is sturdy.
Ridging
In the case of shallow planting, or if the soil coveris thin, extra soil must be applied to the ridge at a later stage. A well developed ridge is very important for undisturbed tuber development. Moreover, a robust potato ridge prevents the developing tubers from becoming exposed, which could lead to them becoming green. Under wet conditions, the potatoes will not lie in waterlogged soil so soon, and a large ridge also affords better protection against high temperatures and damage by the potato tuber moth. The period of time between planting and earthing up must be short if the climate is hot and dry, and if irrigation is needed soon after planting.
| tuber diameter (mm) |
tuber weight (grams) |
expected no. of stems/ha |
number of seed tubers/ha |
seed weight kg/ha |
spacing in row distance 60cm |
spacing in row distance 70cm |
spacing in row distance 80 cm |
| 28-35 | 25 | 2.5 | 60,000 | 1,500 | 28 | 24 | 21 |
| 35-45 | 50 | 4 | 38,000 | 1,900 | 44 | 38 | 33 |
| 45-55 | 90 | 5 | 30,000 | 2,700 | 55 | 48 | 42 |
Number of sprouts & spacing of tubers in the rowThe average number of sprouts per tuber gives a good indication of the number of stems that can be expected. The number of stems determines the required spacing of the tubers in the row. Therefore, to be able to determine the correct distance, it is necessary to establish the average number of sprouts developing from the seed tubers.This is best done by counting the number of sprouts on a representative selection of tuber samples taken from the seed lot.
Row spacingPotatoes can be grown in rows 50-100 cm apart. As a closed canopy at an early stage is conducive to production, it is important to aim at the quickest possible canopy closure when establishing the distance between the rows.The more favourable the growing conditions, the wider the distance between the row can be. A narrow row distance may give a better distribution of stems, but for technical reasons – the opportunity to make good sized ridges to protect the tubers – it is much better to grow potatoes at wider row distances (75-90 cm). In mechanized potatoproduction, row spacing is determined by the standardized setting of the machinery.
Planting depthThe planting depth should be adjusted according to the soil conditions.Under normal growing conditions, the top of the tuber will belevel with the soil surface. As soil in the deeper layers dries out more slowly than surface soil, planting should be deeper in dry conditions. But while dry conditions make deeper planting essential, this is an advantage if temperatures are very high. A greater planting depth will also be important in circumstances in which the potato tuber moth poses a threat. Deep planting is not necessary in moist conditions, as there is no risk that the surface soil will dry out.
Shallow planting is also advantageous in cool conditions. The consequence of greater tuber depth is that a great deal of soil passes through the lifter during mechanical harvesting. Where the soil is heavy, this will be more detrimenta lthan in the case of light soil. Varietal differences also play a role in planting depth variations. This is another reason why growers should be familiar with all the characteristics of their varieties.Earthing up
In addition to planting depth, the depth of the soil cover also influences the development of the new haulm. When planting, only shallow earthing up is carried out if soil temperature is low or the seed is of inferior quality. A limited soil coverage also promotes a rapid initial development. A deeper soil cover, on the other hand, can be applied when temperatures are high and the seed is sturdy.
Ridging
In the case of shallow planting, or if the soil coveris thin, extra soil must be applied to the ridge at a later stage. A well developed ridge is very important for undisturbed tuber development. Moreover, a robust potato ridge prevents the developing tubers from becoming exposed, which could lead to them becoming green. Under wet conditions, the potatoes will not lie in waterlogged soil so soon, and a large ridge also affords better protection against high temperatures and damage by the potato tuber moth. The period of time between planting and earthing up must be short if the climate is hot and dry, and if irrigation is needed soon after planting.