Gardening: How to grow potatoes in small spaces

Even if you only have room for a 30cm pot on your balcony or terrace, you can still enjoy a few home-grown spuds, says Emma O'Neill, head gardener at charity Garden Organic (gardenorganic.org.uk).

Potatoes take up a lot of space in the ground, but provided you buy the right varieties, they can still be grown in a small area, she says.

"If you are growing potatoes in the ground in a small garden, grow first earlies because you can harvest them by the middle of summer and then grow something else," she advises. Buy seed potatoes - which are tubers specifically used for growing - now from a reputable company, as they are more likely to be disease-free.

Here O'Neill offers her guide to planting potatoes in small spots and containers...

1. Start 'chitting'

Put your seed potatoes in an open egg carton or on a tray on a windowsill where they will start to sprout. Some gardeners advise removing some of the weakest 'eyes' as they get bigger, but O'Neill has always left them on and says the potatoes still crop well.

"They won't be ready for planting yet - first earlies such as Charlottes can be planted at the beginning of March, second earlies and maincrops a little later, so you can chit them up until then," she advises. "As soon as they hit the light they will start to sprout."

2. Choose your container

"Some containers are better than others. You can now get grow bags specifically designed for them, or use old compost bags, or a half barrel. A lot of people use dustbins, but the only thing I've found with them is that they tend to exclude the light because they are quite tall.

"If you are thinking about the aesthetics, go for a pot. The only requirement is that it has good drainage holes. The smallest pot you could get away with is about 30cm, but that would only be suitable for one potato plant.

"But the bigger the pot, the bigger the yield. A better size would be, say, 75cm for three plants. The yield would be roughly five potatoes per plant if you space them out. But if you cram them in you will get much smaller potatoes."

To ensure a continuation of crops, if you have enough space plant a first early, a second early - which takes a few weeks longer to mature - and a maincrop in different pots to extend the season, she advises.

3. Throw in the compost

"Potatoes do best in organic multi-purpose compost. You can use your own homemade compost as well, but I'd go for a mix of the two," she notes.

4. Plant the seed potatoes

"Make sure they are in a sunny, sheltered position. Realistically the seed potatoes are quite low in the pot. You'll have about 3-4in of compost on the bottom, then your potatoes - making sure the strongest 'eyes' are facing up - and about 5in of compost over the top of them.

"Leave enough room at the top of the pot to give you space to put on another layer of compost to 'earth up', to cover the green shoots. But if green shoots are showing in late March and frost is forecast, put some protection such as hessian over the pots. You need to 'earth up' every time you see the green shoots appearing through the compost."

5. Keep growth steady

"Watering is the main job but don't let them get too wet because the potatoes will rot. The compost needs to be moist but not saturated. The key is to water little and often. You don't have to feed them but if you want to, use comfrey or a liquid seaweed feed."

6. Harvest when they have flowered

"They should be ready for harvesting between 12-20 weeks after planting, so if you plant them from mid-March you could be harvesting them from June. Wait until they've flowered and the foliage has started to die down and the leaves have gone yellow.

"If the pot is small enough you can just upend it to harvest the potatoes. If you want to take a few out at a time, try to do it by hand because if you use a hand fork, you could skewer them."

7. Consider which varieties are better for pots

O'Neill recommends Swift, Charlotte and Rocket, International Kidney, Pink Gypsy and Maris Bard.