Country Gardener

Widely regarded as the authority on gardening in the south west

How to grow potatoes in bags

It’s become a trend to grow potatoes in bags or sacks. The benefits are less disease, better use of space in the garden for more ‘valuable vegetables’ and often larger crops.

Guess which was one of the top three trends in vegetable growing over the last two years?

It may be surprising but it’s growing potatoes in bags which has caught the imagination and appeal of gardeners.

If you’re lucky enough to have space on your vegetable plot you can grow your potatoes in the ground. If you only have limited space then this is where the trend really flourishes.

Nothing beats that earthy taste of your home grown potatoes. Growing them isn’t as complicated as you might think, particularly if you grow them in potato bags. Potatoes growing in containers are also at much less risk of pests and diseases. 

You can buy seed potatoes for cropping throughout most of the year, including seed potatoes for Christmas which are becoming increasingly popular.

To grow potatoes in bags in your small garden...

Plant two tubers in an inside-out compost bag or extra thick bin liners in the greenhouse in February or March. Inside out, the bags are black and absorb any heat going ‘International Kidney’ and ‘Belle de Fontenay’ for forcing, or ‘Charlotte’ are good bag growing varieties.

Roll down the sides of the compost bags to about half their height, make a few holes in the bottom of the plastic for drainage and fill the bag to about the depth of 30cms. 

Earth from molehills will give you lovely crumbly loam where the moles have done lots of the hard work for you. They create the most delicious, friable grass-free soil from a depth usually below the worst of the weed seed.

Put in two tubers per bag and bury them in the soil/compost mix and back fill another 15cms or so on top. Water them in well. Put your sacks somewhere bright, frost free and a little warm. Within three weeks or so, they will have begun to shoot.

Keep the compost damp, but not sopping wet. Once the shoots are about 15cm, roll up the edges of the bag a few turns and fill up to that level with more soil/compost mix. Carry on earthing them up, bit by bit every couple of weeks, until they reach nearly the top of the bag. Then allow the shoots to come up to flower, which should be in May, and you can start to harvest.

You can turn out a whole bag at a time. It’s easiest to do this into an empty wheelbarrow, but with some varieties the flavour is better when harvested and eaten straight away, not stored. Some of the sugars in the tubers convert to starch when stored so the flavour gradually disappears.

For this reason, it’s worth perfecting your potato milking technique: cut off a corner of the bag and put your hand in from the bottom. Harvest and eat only what you need for each meal. 

How long does it take to grow a potato?

It is tempting to harvest potatoes as soon as possible to enjoy them in meals but different varieties can take anything from 70 to 120 days to grow. So, while the early-season potatoes will be ready to consume by the end of May or early June, others will need a bit more patience.

Potatoes also come in early, late and mid-season varieties that vary in length of time to harvest. On average, you can expect about five to ten potatoes per plant.

potatoesHow to grow perfect potatoes in bags

  1. Chit tubers to produce sturdy shoots in a cool light place.
  2. Start your grow sacks in a greenhouse or conservatory from as early as February and move outside once the frosts are over.
  3. Grow them in a light, warm, sunny spot.
  4. Use a good proprietary compost or an equal mix of compost and soil and place a layer four to six inches deep in the bottom. Place the potatoes on the compost and cover with a further six inches of compost.
  5. Potatoes grow from the stem beneath the surface - so keep covering the foliage with more compost.
  6. Feeding and irrigation is the big secret. Mix a potato fertilizer or a good general purpose fertiliser such as Growmore during planting earthing up.
  7. Potato blight can be a big problem with later yielding crops.
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