Long live the spud
Peter Cundall’s potato tips
IF you haven’t planted a potato crop yet, there’s still plenty of time. In frost- free districts they can still go in after Christmas. However, the later your certified seed tubers go in, the later the harvest. That means potato plants will be still growing during the warmer, drier parts of late summer, so more irrigation will be needed to obtain a decent yield.
I planted our own crop about a month ago. Due to over- wet soil conditions I was a bit later than usual, but they are doing well. Over the past couple of weeks the foliage has been pushing through the soil. Once the leaves become energised by sunlight, they move very fast. This is a good time to apply well- rotted animal manure or pelletised poultry manure along the rows. I also add a fistful of sulphate of potash to every metre of row.
Once leaves and stems are well above soil level, the next most urgent job is earthing- up or mounding. I use a heavy hoe or a spade to draw up enough soil from around each individual plant to completely bury almost all new growth. For exceptional yields and healthier plants, mounding is best carried out three times during the life of the crop. The benefits are worth the extra bit of effort.
Seed potato tubers are different to most bulbs, rhizomes or other tubers. Once planted in moist soil, usually about 20cm deep, they do not send down roots. Instead, they send sprouts upwards towards the light.
These sprouts have a double purpose. They produce the main feeding roots, above the seed tuber. At the same time tiny, pea- sized immature potatoes form at the tips of each sprout, also beneath the surface. These eventually grow into the full- sized spuds we eat. In other words, a potato crop is always formed much closer to the surface than the original seed tubers. The way potatoes form and swell is partly why
mounding is so beneficial. Burying lower stems below the surface forces extra side- shoots to emerge so more potatoes are produced.
Mounding is also an excellent means of controlling masses of small, annual weeds by disrupting and burying them.
An extra depth of soil also prevents growing tubers from being thrust into the light, where they would be wasted by turning green and too poisonous too eat.
Mounding is also an effective way to control a serious pest, the potato grub. In summer, as crops are maturing, potato moths lay eggs on any potatoes that are exposed or too close to the surface. The grubs hatch and create dirty tunnels through the tubers, making them inedible.
All potato crops benefit by deep irrigation every 10 days. Once potato plants begin to flower, it is a reliable indication that some tubers have already grown big enough to eat. It is worth probing around beneath some of the more vigorous plants to grab a tasty feed of early spuds while leaving the rest to keep on growing. These first new potatoes make particularly delicious eating.
Later we can see a potato crop maturing because the foliage starts to lose vigour, taking on a yellow colour and beginning to flop over the ground. When this occurs, all watering must immediately cease, otherwise the crop can be ruined.
Never leave potatoes in the ground after the foliage has finally withered. The holes in the soil left behind by the dead stems become access points for potato moths. Also, just a couple of heavy rains are enough to cause the tubers to rot, especially in warm soil.
All potatoes must be lifted, any soil blasted off with a hose, and then left spread out in the sun for a few hours to safely dry.
Finally, pack into cardboard boxes or hessian bags. If stored in complete darkness they will last in good condition until August or even later.