If you’re new to gardening vegetables, potatoes are a good one to get you going. Just about everyone likes to eat them – boiled, mashed, baked or as chips. They are inexpensive to buy, but growing your own means you can try varieties you can’t easily get in the shops and you can ensure they will be chemical-free.
February and March are the best months for starting your potato growing season. Get down the garden centre or Wilkos to buy a bag of seed potatoes. You could use ones you’ve bought in a supermarket – especially if they’ve already started sprouting, but some shop-bought ones may have been treated with sprout inhibitors so won’t take.
Get a head start by ‘chitting’ your potatoes, which should mean both an earlier harvest and a better crop.
Chitting is basically another word for sprouting which you encourage by exposing your potatoes to warmth and light. You’ll need somewhere to put them which is around 8-10 C (50F) so a porch, conservatory or garage is about right or somewhere else which gets a bit of heat, but not too much. It needs to be frost-free so a greenhouse is ideal.
You’ll need some old egg boxes or seed-trays or other boxes with ruffled up newspaper in them – or any container where you can put the potato tubers upright, stacked side by side with the ‘rose end’ facing up. This is the end with the most small dents in the skin or ‘eyes’ and the eyes are where the sprouts will start emerging in a few days.
.You’re aiming to plant them out at the end of March for the ‘First Earlies’ – varieties like Arran Pilot. ‘Second earlies’ like Charlotte, Kestrel or Wilja, should be planted out a bit later – early to mid April. Main crops like Maris Piper, Desiree or Pink Fir Apple go out mid to late April. But these are approximate times, it all depends on the weather, how sheltered the growing conditions etc. It’s trial and error – or ask someone on the site who grows potatoes regularly.
Chitting is not essential, especially for main crop potatoes, but if you are trying to chit before planting, the sprouts should be small, knobbly, and green/purple in colour. The time to plant is when they are about 3 cm (1 inch) long. If you want a good harvest with fewer but bigger potatoes, best to rub off the excess chits (or sprouts) over and above 2 or 3. If you end up with long, white coloured sprouts, it means there’s not enough light – or you’re sprouting shop bought potatoes!
Planting out
When to plant outside
Frost kills a lot of plants, and the general advice for many of them is to ‘plant out when the danger of frost has passed’. Easier said than done as sometimes frosts return after an early spring. The UK average for the last frosts is the last week of April which is why May is the typical month for planting out. With potatoes, you’re aiming for the foliage to appear above ground after the frost danger has passed, and it takes seed potatoes about 4 weeks to that to happen with main crop potatoes. So the last week in March is roughly the right time – traditionally potato planting is an Easter activity, but Easter dates vary and the Earlies usually go in first.
Why not ask your neighbour on the site when they plant theirs? – this will be when it suits local conditions best.
If you’ve missed the best time, it just means you’ll get a later harvest or less of a harvest.
Where to plant
- Planting in the ground: choose a sunny site away which doesn’t suffer from frosts, turn it over with a fork and clear it of weeds. Dig a narrow trench 12cm (5in) deep. For a better crop, line the trench with compost or even grass. Space the seed tubers 30cm (12in) apart for earlies and 37cm (15in) for maincrop varieties in rows 24in (60cm) apart for earlies and 75cm (30in) apart for maincrop.
- Grow under black polythene. Lay out a large sheet of polythene on the weeded dug-over soil and cut holes at 30 cm intervals. Plant the seed tubers, sprouts facing up through the holes. The advantage of this method is that there is no need to earth up and the new potatoes form just below soil level which means there’s no digging to harvest them.
- Grow in raised beds or large, deep containers or bags. This is a good way of getting an early batch of new potatoes. Line the bottom 15cm (6in) of the container with potting compost and plant the seed potato just below this. As the new stems start growing, keep adding compost until the container is full.
Looking after your potatoes
Once planted, care consists of watering in dry weather and making sure the newly emerging foliage is protected from frost damage and from light. Light turns tubers green and green potatoes are poisonous
The vital time for watering is when the tubers start to form. You can also add a liquid feed of a balanced general fertilizer every couple of weeks if you want to increase the yield.
To protect from frost and light, you need to earth up potatoes growing in the ground. Start doing this when the plant stems are about 23cm (9in) high. Carefully draw the soil up to the stems and cover most of them to produce a flat-topped ridge about 15cm (6in) high. This can be done little and often or in one go. If you’re not sure how to do this, just ask – most allotment gardeners have some experience of growing potatoes.
Harvesting
The potato harvesting season runs from June and July for first earlies to October when you would aim to lift the last of the main crops ready for storing. Second earlies including salad potatoes like Charlottes should be ready in July and August, and maincrops from late August.
How do you tell they are ready? For earlies wait until the flowers open or the buds drop. People usually harvest them when they are the size of hens’ eggs – try digging up one plant if you’re not sure. Earlies are most delicious when eaten fresh, but Charlotte for example keeps very well too.
For the maincrop potatoes which you will want to store over the winter as well as eat fresh, you want to make sure they have grown to maximum size. So wait until the foliage turns yellow, then cut it and remove it. Leave for 10 days before harvesting the tubers, leaving them to dry for a few hours before storing.
A few warnings
Potato growing is not without its problems. Disease can wreck harvests and cause famines at worst – witness the Irish Potato Famine in the mid 1800s. So it’s not surprising that modern farmers use chemicals to prevent this sort of catastrophe. Many allotment gardeners want to avoid using chemicals if they can, so the best advice for gardeners is to
- Buy good quality varieties which resist the main diseases,
- Check for signs of disease on any stored potatoes from last year and don’t use infected ones
- Practise crop rotation – don’t grow potatoes in the same place every year
- Be vigilant while the potatoes are growing, and act quickly if you see signs of disease
Here’s the advice from the RHS (Royal Horticultural Society) on the most common diseases:
Potato blight: This is a common disease in wet, warm summers. The initial symptoms are a rapidly spreading brown watery rot, affecting leaves, and stems. Tubers can be affected too, and have a reddish-brown decay below the skin, firm at first but soon developing into a soft rot.
Remedy: Unfortunately once blight starts, it is very difficult to stop. You can remove blight-affected leaves, but removing too many leaves will damage the plant’s ability to grow. Earthing up potatoes provides some protection to tubers. There is no chemical control to stop blight, but you can spray with a protectant spray in June if it looks like it will be a wet one.
Potato blackleg: Potato blackleg is a common bacterial disease which causes black rotting at the stem base. Initial infections cause stunted growth and yellowing stems. If tubers form, the flesh may be grey or brown and rotten.
Remedy: Remove and destroy infected plants. Rotate crops. Buy resistant varieties such as ‘Charlotte’, ‘Pixie’ and ‘Saxon’.
Potato scab: This disease causes raised scab-like lesions on the potato surface. It does not affect the taste of the potato, and is easily removed on peeling.
Remedy: There is no control for scab, and you usually won’t know anything is wrong until harvest time. Scab can be worse in dry weather, so keep potatoes well watered. Don’t store any potatoes with scab.
Potato rot: Potato tuber rots are a frequent cause of losses prior to, or after, lifting. Significant problems often follow a wet growing season, particularly if the tubers are then lifted from wet soil.
Remedy: Use good quality, resistant certified seed tubers when planting and harvest when the soil is neither wet nor very hard and dry. Store in cool, dry conditions.
Good luck and enjoy your potatoes!
Which potatoes to grow?
There are so many varieties to choose from. Here’s a few you could try which have been grown on Ward End Allotment sites. Some of them you’ll find in the supermarket, others are mainly grown by amateur gardeners. Garden centres, large nurseries and shops like Wilko won’t stock them all, but if you plan ahead, you should be able to get the ones you like.
Aran Pilot: 1st Early potato, delicious when eaten freshly boiled, very popular
Charlotte: 2nd Early yellow potato, high yields, and easy to grow; excellent for boiling and use in salads, holds its shape well when cooked
Kestrel: 2nd Early potato, one of the easiest to grow, does well in heavy soils and disease and slug resistant. Excellent flavour and especially good for roasting and chips
Wilja: 2nd Early potato, very versatile and tastes of real potato. Good yields.
Maris Piper: Main crop, one of the most productive potato varieties and the chef’s favourite for cooking, especially chips, baking and boiling. Not very resistant to diseases and eelworm (so commercial growers use a lot of chemicals and fertilisers)
Desiree: Main crop red-skinned potato which keeps its shape well when cooked. Good for boiling, mashing, chipping and roasting. Grows big for harvesting later in the season and storage, but can be lifted earlier when they are smaller.
King Edward: Main crop, well-known general purpose potato, excellent for cooking and eating.
Majestic: Main crop potato, suits a wide range of soils and good yield and keeping quality. General purpose potato
Pink Fir Apple: Main crop, knobbly potatoes, very tasty boiled or as salad potatoes
Apache: 2nd Early red-skinned potato with cream coloured patches – very tasty baked in their skins or roasted.
Pink Gypsy: Main crop potato, good overall disease resistance. Excellent flavour and good all-round cooking qualities.
Cara: Main crop potato, high yielding and disease resistant. General purpose for cooking.
Jazzy: Large oval salad potatoes, ideal for planting in bags. High in flavour, low in fat.
Vivaldi: 2nd Early yellow potato with excellent flavour. Good for boiling, mashing and baking.
Winston: 1st Early, good flavoured potato ideal for baking which wins awards on the competition show bench.