Getting started with growing potatoes
What we consider a potato is technically called a tuber. A tuber is a store of food, and that's why potatoes are such a great vegetable to grow. They will give you one of the highest yields in terms of calories of any home crop. The potato plant's purpose in life is to store food underground.
My favorite variety of potato is desiree. But anything recommended by your local garden center, or sold at local markets, is worth a try.
It is a good idea to buy seeds that have been certified disease free for your first year. After that you can simply save some of your crop to start next season's crop.
Leave potatoes on a sunny windowsill for a week or so to sprout. If they already have visible sprouts (at least 1cm or 1/3 inch long), they can go straight in the ground.
Prepare the soil to a depth of at least 30cm (12 inches), see soil preparation. Potatoes are gross feeders, and incorporating some compost and well rotted manure before planting will give you a good head start.
Plant potatoes deep, a minimum of 10cm (4 inches). You can plant them up to double that depth. If you buy seed potatoes the packet may recommend a shallower depth but the deeper you plant them the more room there is for the potato tubers to develop.
Some people dig trenches, but I find it easier to use a trowel to dig individual holes. For a good yield, space 30cm (12 inches) apart in rows at least 50cm (20 inches) apart. Cover and water well. Don't over water from this point.
Plants will poke through the soil within 1-3 weeks depending on the weather and the variety chosen.
Growth is rapid over the next month after emerging. Within a few weeks they will have plenty of foliage (see photo)
Once plants get high enough, mound soil up around the rows, covering the lower part of the stems. This action protects the tubers from sunlight and gives them extra room to develop.
Most varieties of potato take about three months to be ready for your first harvest. Early, fast growing varieties like rocket can be ready in two months.
Carefully dig down beside the first plant at the end of the row with a fork. Dig deep at first and then work inwards to avoid stabbing your precious crop. You may get a few smaller potatoes as well as some larger ones, this is normal. But if they are all to small to use easily, then you may need to wait another 1-3 weeks and try again.
If you plan to store potatoes for longer than a few days you need to let the plants die down completely before you dig.
Once dug, leave the crop in the sun to cure for a couple of hours (short exposure to sunlight won't harm them) and then store in a well ventilated dry place. We store ours in a dark closet and they last for months at a time. Do check them every now and then and remove any shoots that have formed.
You will note in the photo that the potato tops have completely dried up. The green plants are weeds, which I will want to pull out before they go to seed!!
After a few months stored potatoes may begin to shrivel and send out multiple shoots. If this happens heading into spring (or you live in a frost-free climate) then you can plant these potatoes back in the garden for your next crop.
Remember that sunlight is the enemy of stored potatoes. exposure to light during storage will turn potatoes green and green potatoes are poisonous.
Tips and things to watch out for
Potatoes grow so quickly in most climates that by the time they succumb to fungal diseases they are usually ready to harvest. But avoid over watering the foliage as wet leaves can speed up fungal attack.
Viral diseases are another story. If you are consistently having problems growing potatoes it could be a virus. Throw out all your seed potatoes and buy fresh ones that are certified disease free.
There are some bugs that like to attack the tubers (including the potato tuber moth). Unfortunately I haven't found any organic treatments that are effective. But when we have had damage, it is usually on a small scale. Throwing out the odd tuber is a small price to pay for remaining organic.
If you get large-scale problems with bugs you may have other issues (unhealthy plants) or just be unlucky. There are chemical sprays available at your local garden shop but I don't like going down that path.