Growing Potatoes



Latest Update 7th May 2017.

Potatoes
  • Potatoes are a staple crop in our household, and we can usually grow enough to last 6 months in our limited space.
  • I prepare the potato bed with lots of compost and a crop of green manure which is cut and laid on the soil as a mulch prior to planting the seed potatoes.
  • I usually take delivery of certified seed potatoes in mid June, and after chitting them for about 6 weeks, I plant them.  The weather starts to improve soon after, and damaging frosts are usually gone by September when the tender shoots start to emerge from the soil.
  • We harvest a few new potatoes as soon as their flowers set in early November.  They are delicious when steamed, mashed or baked in their jackets.
  • If you delay harvesting the main crop until the foliage has died back completely the tubers store longer.


Details.
  • Binomial Name:                                        Solanum tuberosum. 
  • Family:                                                    Solanaceae.
  • Variety:                                                    Nicola. 
  • Crop rotation group:                                  Solanaceae. 
  • Garden bed type:                                      Garden Ecobed.
  • Recommended soil pH:                             4.5 - 6.0. 
  • Minimum sun per day:                               6 hours.
  • Plant spacings (centres x rows):                250 x 300 mm.
  • Weeks to harvest:                                    15 - 20 weeks.
  • Good companions:                                    Pea, bean, cabbage, nasturtium, marigold.
  • Climate:                                                   Warm temperate.
  • Geography:                                              Southern hemisphere. 
Nutrition.
  • This food is very low in saturated fat, cholesterol and sodium. 
  • It is a good source of dietary fibre, and a very good source of vitamin C, vitamin B6, iron, potassium, copper and manganese.
  • More from nutrition data.self.com. 
Growing Conditions:
  • They grow best in full sun. 
  • They need well structured rich organic soil.
  • Frost damages leaves and halts growth.
  • Tuber formation is most vigorous when temperatures are from 16 to 20 deg C, and it stops when temperatures exceed 26 deg C.
  • Potatoes prosper in good organic soil.
Soil Preparation
  • A crop of Autumn green manure mix containing vetch, field peas and oats is planted in early autumn.  Cut down with garden shears, as soon as flower buds start to form in mid winter, its shredded and moved to one side .  The roots are left in the soil to decompose and release the nitrogen collected in their rhizobia nodules.
  • The green manure is shredded and sprinkled over the soil followed by a 60mm layer of thermal compost applied as a top dressing.
  • A 50mm layer of fresh straw mulch covers the manure to help maintain moisture in the soil and compost.
  • The bed is left for 6 weeks to build up worm and microbial activity before planting the potatoes.
Growing Instructions.
  • Purchase your seed Potatoes in May for deliver in mid June.  Use a certified supplier to avoid disease (buy 48 tubers).
  • To get earlier growth you should "chit" them by placing them (eyes up) in a warm spot with plenty of indirect light for about 6 weeks.
  • After a week or two the seeds will send out new shoots.  
  • Reduce to 3 or 4 shoots to grow larger potatoes, but leave them to produce more shoots if you're happy with smaller potatoes
  • Dig planting holes through the mulch in late August, 250mm apart (6 tubers) along rows 300mm apart (8 rows).
  • Sow the seed potatoes 200mm deep and cover them with about 50mm of soil.  Make sure the shoots are facing upwards and take care not to damage them.
  • Backfill gradually with soil as the shoots grow, but make sure the growing tips are never completely covered.
  • Apply a foliar spray of aerated compost tea every 4 weeks during the active growth stage. 
  • The soil must be kept moist during this stage, but can be left to dry out when the plants begin to die back (don't let the Ecobed's water tank empty, but keep the water level low during this stage of growth).  The plants draw back nutrients and moisture from the leaves for use in their tubers.
Harvesting and Storage.
  • Young potato tubers are delicious and well worth sacrificing some of the main crop harvesting them early.  
  • Harvest these "New Potatoes" as soon as flowers appear by digging up a whole plant.  Use all of the tubers before harvesting the next plant.
  • Harvest the main crop for storage 2 weeks after the foliage dies back (usually in late January).
  • Use a hand trowel to harvest your main crop.  Push the trowel into the soil at an angle so that it is below the clump of Potatoes and lift the whole clump.  Take care with the trowel as you don't want to disturb the water tank's cover or perforate the liner.
  • Wash the tubers and leave them in the open air to dry.  Don't leave them in hot sun too long as they can be damaged.
  • Store your Potatoes in a cool, dark, dry place in a hessian sack or cardboard box.  Note** They will rot if they are not perfectly dry.
  • Check on them from time to time, and remove any tubers starting to rot.  
  • After a few months the remainder of your crop may start to sprout.  It is worth going through your stored Potatoes at this stage to rub out these new shoots.  This will prolong the storage life of your crop.
  • Alternatively you can preserve (pressure cook) potatoes in a saline solution for longer term storage (see article) in preserving jars.
Organic Pest Control.
  • Slugs and snails. 
    • Potatoes need protection against slugs and snails, so use self adhesive copper tape around the base of the Ecobed to keep them out.
  • Greenhouse Whitefly.  
    • A foliar spray of aerated compost tea strengthens the plant's tissue to help control whitefly damage. 
    • Control any serious infestations by spraying your crop thoroughly with organic horticultural oil (Eco-oil in Australia). 
    • Spray again after a few days to ensure second generation whitefly do not survive.
  • Root knot nematode.
    • There are many ways to kill root knot nematodes but few of them are selective.  
    • Even approved organic methods like sowing a crop of mustard soil fumigant will kill beneficial soil microbes as well as the pest.
    • Crop rotation is the most effective defensive measure.  It doesn't allow the pest to establish itself because the crop is only grown every fourth year in each bed.
  • General.
    • Generous applications of homemade compost and green manure keep biological activity in the soil at a high level.  This biological activity controls soil borne plant pathogens.
    • Do not dispose of infected plant tissue in your compost unless you are confident you can generate enough heat to kill the pathogens.  Dispose of this waste in plastic bags in the garbage bin.