Pre-sprouting organic potatoes

• Cooling
  Air cooling is usually sufficient. However, additional mechanical cooling can sensible from September onwards.
• Top sprout
  For organic cultivation, it is generally better to retain the top sprout on the tuber. It is important to supply large enough (40+ mm) potatoes with sufficient underwater weight using relatively few tubers (6-10) . This will produce a good yield before any Phytophthora infection.
  There are some exceptions:
  – High-yielding varieties with strong Phytophthora resistance.
  – Varieties with few tubers per plant such as Agria and Triplo
  Top sprouting may be recommended for the best performance from these varieties.
  See the advice page for fresh potatoes for advice on top sprouting.
• Warming
  If the seed potatoes are very cold and/or it is late in the season, it is a good idea to warm the seed potatoes. In practice, this is usually done at a temperature of 18°-20°C for 3-5 days. Continue heating until the white sprouting tips appear. Then stop heating immediately. Ensure there is enough oxygen in the room.
• Hardening off
  Indoors: an insulated shed with plenty of natural draught is the best option. Ensure there are doors or shutters in the shed that can be opened.
  Outdoors: this gives the best hardening off results.
  – Place the pre-sprouting racks in the windiest position in your yard.
  – Place the racks 1 m apart.
  – Place the racks in a north-south direction if possible.
  – Move the pre-sprouting racks indoors if there is a risk of frost.
  – Ensure maximum ventilation. Use indoor ventilation if necessary.
  – Place the racks outdoors again as soon as possible.
• Transfer to another bag
  If the pre-sprouting racks are outdoors or in a shed, this is not necessary. With a late spring, the leaves on the trees around your farm can inhibit the wind from the end of April. Place the pre-sprouting racks in another windy place if possible and let the power of the wind work for you. If this is not ideal and the sprouts have become too long, you can transfer them to another bag once. Lift a full rack above an empty rack with a forklift. Loosen the Velcro fastening from a full bag to release the seed potatoes into the empty pre-sprouting bag.
  
• Hardening off time
  At least 5 weeks. After that, the longer the better, provided that the pre-sprouting bags are fully exposed to the wind and sunlight.
• Which pre-sprouting bag?
  Standard pre-sprouting bag (10 cm cord). Capacity 100 kg per bag. Rain covers are not necessary if hardening off takes place indoors. A rain cover is recommended if hardening off takes place outdoors.

* ALL ADVICE GIVEN APPLIES TO AVERAGE CONDITIONS IN THE NETHERLANDS. AS WE HAVE NO INFLUENCE ON THE QUALITY OF SEED POTATOES, WEATHER, BUILDINGS, MACHINERY AND THE EXPERTISE OF THE USER, WE CANNOT ACCEPT ANY LIABILITY FOR THE RESULTS.