Pre-sprouting during a
harsh winter and
short spring

Advice on how to pre-sprout in climates with harsh winters and short springs

Utilize as much reflection
Reflection does not cost energy. Make the walls and floor white. This can be done by painting or attaching white cloth.
Pre-sprouting bags fill: 4-8 weeks before the expected time of planting
Temperature in the barn: 4°C to 12°C
Sprouting inhibition in the barn occurs primarily through UV light
a. This occurs preferentially through sunlight through a window or skylight in the roof.
b. Through artificial light– fluorescent lamps: 1 TL lamp per germination rack
Halogen lamp: 1 HPI-T lamp per 6-8 racks
Warning with artificial light:
– Do not use LED lamps: they give no effect because they do not contain UV light that causes growth inhibition and discoloration of germs
– Do not use UV lamps: they give too much effect and are dangerous to your health
If the outside temperature is above 2°C, open the doors so the wind can remove condensation, CO2 and excess temperature. Preferably make doors or shutters at the back of your shed so the wind can do this job better
If the temperature is also at night above 2°C then drive the presprouting racks outside for further hardening. Place the pre-sprouting racks in the most windy place. Stack 2-high, with 1 meter spacing, on a paved surface. in this way you will make the best use of the best place possible
If the temperature is more than 5 days between 0°-3°C there is a chance of cold damage to the tubers. They may then be externally beautiful but no longer germinate
BECAUSE WE HAVE NO CONTROL OVER SEED QUALITY, WEATHER, BUILDINGS, MACHINERY AND OPERATOR EXPERTISE, WE CANNOT ACCEPT ANY LIABILITY FOR THE RESULTS.

Pre-sprouting in

a frost-free barn

Use a frost-free barn
Make sure there are no residues of sprout inhibitors in your shed

Fill the pre-sprouting bags about 6-8 weeks before the expected planting date

Photo: pre-germination near Tromsø, Norway. (300 km. above the Arctic Circle)

Check

the temperature

Seed potatoes must not freeze or suffer cold damage.
If seed potatoes are at a temperature of 0°C to 3°C for more than 5 days, cold damage begins. If cold damage occurs, the tubers look fine but germinate poorly or not.

Photo: Hokkaido, Japan

Exposure with

halogen lamp

The sprouting of seed potatoes must get going. When the white tips of the sprouts become visible, braking by wind and UV part of the light starts. This keeps the sprouts short and strong so they do not break off when planting. The UV part of the light gives the sprouts a green or purple color.

For small-scale pre-germination, a fluorescent lamps (TL lamp) are suitable.
Advice: 1 lamp per pre-germination rack. For large-scale pre-germination, gas discharge lamps (HPI-T, HID lamp) are suitable. Advice 1 lamp per 6-8 germination racks

Advice: hang these lights 3/4 part from the ceiling. 1/4 part on a cart illuminating the pre-sprouting bags from the side. Drive the cart 1 m. further each day to reduce shadow effect.

Do not use LED lamps: these lamps have no effect because there is no UV light in them
Do not use UV lamps: these lamps work too brightly and are bad for your health.