Growing Potatoes

Source: Green Harvest

BOTANICAL NAME: Solanum tuberosum
COMMON NAMES: Spuds; taters; patata (Spanish); patat (Italian); pomme de terre (French); aardappel (Dutch); ziemniaki (Polish); alu (Hindi, Nepali, Bengali); kentang (Malay, Indonesian)
FAMILY: Solanaceae, the tomato family

Potatoes like a fertile, deeply dug, moist, acidic soil with a pH of less than 6. They do not grow well in heavy clay or a limed soil, which promotes potato scab. To avoid this, always rotate your potato patch each year. Many older varieties of potatoes have lost favour commercially because of either deep eyes or an irregular shape but may have many advantages to the home grower in hardiness, disease resistance and prolific production.

Food: potatoes are a staple, many heritage potatoes have a superb flavour whether used as an 'old' potato and baked or used as a 'new' potato and steamed or mashed.

Potato plant and tubers

Recommended planting time: Potatoes can be grown in many months of the year, depending on whether the garden receives frost, as potatoes are frost-tender. Potatoes need 60 o 90 days frost-free to be successfully harvested; potatoes harvested early as 'new' potatoes do not store well. In northern NSW and QLD one of the best planting times is March-April, as the soil is warm, growth is rapid and there are generally less pests. For frosty areas, potatoes can be planted in early spring, shortly before the last expected frost. Planting can continue into summer although the risk of pest and disease damage increases as the weather becomes hotter, particularly in humid areas. Green Harvest offers certified seed potatoes in March-April and July-August.

Potato varieties can be either determinate or indeterminate, just as tomato plants are. The big difference between the 2 types is whether you need to mound the soil or not as the potatoes grow. The majority of types available to the home gardener though are indeterminate and so do need mounding.
Determinate Varieties
These types produce tubers in one layer just below the soil surface and so do not require mounding of the soil around them. They are usually less productive than indeterminate types but do produce spuds earlier, in about 70 to 90 days. If you live in a very cold climate these are the best choice. Plant determinate seed potatoes about 10 cm deep and mulch well. Available: 'Kennebec', 'Kipfler', 'Purple Congo', 'Pink Eye'.
Indeterminate Varieties
These produce tubers in multiple layers, so it is important to keep mounding soil around the plants, to give you the best yield and support the plants well. Indeterminate potatoes can take longer to produce a crop, about 80 to 120 days. They are the best choice if you are growing spuds in a tyre tower or potato bag. Indeterminate types include: 'Desiree', 'Dutch Cream', 'King Edward', 'Nicola', 'Pink Fir Apple', 'Pontiac', 'Sebago'.

There are many different ways to plant including containers, tyre towers, no-dig and traditional hilling. All these methods can be very successful and potatoes are an easy crop to grow.

If you have selected a determinate variety, preparation involves digging over the soil, adding compost and planting the tubers 10 cm deep, about 35 to 40 cm apart. The 'no-dig' method which involves simply placing seed spuds on the surface of the soil and mulching heavily also works best with determinate types. The potatoes will form tubers on top of the ground rather than up through the mulch where they risk being exposed to light. The downside of this simple method is if you fail to keep the mulch thick enough you will harvest green potatoes.

If you have selected an indeterminate variety, preparation involves digging a shallow trench 20 cm wide and 20 cm deep. Place compost in the bottom of the trench, cover with a thin layer of soil and plant the seed potatoes 35 to 40 cm apart and cover with 10 cm of soil. As the potato plants grow continue filling in the trench until the seed potatoes are buried to a maximum depth of 30 cm. Mulch well. Planting in containers, raised beds or tyre towers use the same method.
If you are planting multiple rows space them 50 cm apart.

Cutting seed potatoes into smaller pieces can increase the risk of rot in humid areas. If you do cut into smaller pieces, leave plenty of flesh with each eye and allow the cuts to dry for 24 hours before planting. Cutting into too small a piece can dramatically reduce yield.

Potatoes are ready for harvesting when most of the tops have withered; this can be from 12 to 20 weeks after planting, depending on the variety. Early potatoes may be dug for table use at any time but for storage the potatoes should be fully mature. After they are dug, dry as quickly as possible, and then store immediately in a cool, dark, dry place. Exposure to light will turn the potatoes green; green potatoes are poisonous and should not be eaten. It is usually possible to save some of the harvest from a crop of certified seed potatoes for replanting. Doing this more than once can dramatically increase the risk of disease. Potato diseases can take years to eradicate from a garden.