How to Grow Potatoes
How to Grow Potatoes
Growing potatoes is easy and they need only need limited attention during the growing season. When growing potatoes it is a good idea to earth them up, (see below) water them if dry and feed them, if you have time. If it is a reasonable summer with no blight, potatoes will grow with little attention.
Best tips when growing potatoes
1. Always earth up potatoes even if you are growing in pots
2. Take great care not to damage the top growth especially when earthing up
3. Water well, potatoes need a good amount of rain to grow well and feed regularly.
How to chit Potatoes
Several weeks before you want to grow the Potatoes put the potato tubers in a light cool room allowing shoots to form for about 5-10cms .(image right) The best time to do this is in February for planting out in March, but it's not essential if you don't have the time. There is much debate whether chitting potatoes makes any difference and commercial growers manage without it . Advise on how to grow potatoes often recommends chitting, but there seems to be equal informed opinion to the effect it makes little or no difference to the crop whether the tubers are chitted or not.
When to plant potatoes
When growing Potatoes they do take up a lot of space and unless you have a large veg plot you will not have room for much else. To save space you can also grow potatoes in containers.
Potatoes grow well in pots, place 3 or 4 tubers in pot with 15-20cms of good compost in the bottom and cover with 10 cms of compost. If you want to plant in the plot, about 13cms deep and 30cms apart. If you have chitted the potatoes handle carefully so as not to damage the shoot and plant with the shoot upwards.
It is advisable not to grow Potatoes in the same ground each year or where you have grown tomatoes previously (which are the same family, Solanum) because of the risk of blight which has been a problem with wetter summers. Blight causes the foliage to turn yellow and collapse. Potatoes grown earlier in the year are less likely to be effected, which are the earlies and salad potatoes.
Protect the new top growth called haulms, from frost. Potatoes are not frost hardy (What does "frost hardy" mean?) which means early in the year the top grow needs protection from frost. As soon as the shoots appear earth up or cover the growth by adding more soil in the pot.
Earthing up is important and means as the top growth appears extra soil is added to the pot, or scraped up around the potatoes if in the ground, to form a mound and continue with earthing up as the potato grows. (see image right) The potatoes form under the soil beneath the plant so a good depth of soil or compost is need to for the potatoes to grow. If the potatoes are in the veg plot earth up to create raised ridges up to 30 cms. Earthing up will help to increase crop yields. The only maintenance is to water the pots in dry spells.
Plant earlies in March, April, second earlies and salad in April, and Maincrop in April.
Potato Blight is the main problem when growing potatoes. It is an air bourne fungus like disease which attacks the foliage (and later the tubers) causing it to collapse. It commonly occurs in wet, mild and humid conditions and is difficult to manage. It will affect tomatoes as well although if they are grown in a greenhouse this may afford some protection as it is mainly, but not exclusively a disease of out door crops. It starts with brown marks on the leaves and spreads so that all the foliage turns brown or black collapses and the plant looks patently sick; it cannot be missed. Once it takes a hold there is not much that can be done as it spreads rapidly.
Good air circulation can help and non organic gardeners can spray with Bordeaux mixture which has to be done from June onwards before any signs of the disease appear. Later varieties are more prone so earlies and salad potatoes may escape as the warmer humid temperatures are more likely later in the year.
If the plant becomes badly infected the only possibility is to cut off all the infected leaves close to soil level and be careful to pick up all bits of infected leaves. If the blight has not reached the tubers they can still be harvested later, if the blight occurs later in season, so the tubers have grown sufficiently to make a decent meal.
There are also varieties offered for sale by garden centres and on line which are more resistant such as Sarpo range and it certainly worth looking at this range if growing maincrop which will mature later.
Which Pototoes to Grow
Which potatoes to grow is always a question of personal choice and space. Potatoes take up a lot of room even in containers. There are several different types of Potatoes, first and second earlies, Salad potatoes (harvest June onwards) and Maincrop (harvest later in the season).
Earlies, which as the name suggests mature more quickly, so you can harvest sooner.
Earlies take about 16-17 weeks to mature, maincrop 18-20 but can be left in the ground until October and generally store well.
Earlies are slighly less prone to blight, Maincrop take up more space and for longer so there are advantages each way.
For main crop, when blight is often a problem a good choice would be organic Potato 'Sarpo Mira' in an attempt to beat the blight later in the year. They are saidto be one of the most blight resistant potatoes.
You may have a personal preference, if not a good starting point is to look at varieties which have the RHS garden merit award
In 2013 the RHS did a trial of first earlies and best early salad potatoes grown in containers. Those varieties which gained or retained the award were: 'Casablanca' a waxy white fleshed potato, 'Golden Nugget' waxy, 'Sharpe's Express', 'Maris Beard' 'Lady Christi' 'Jazzy' 'Vales Emerald' and 'Charlotte' worth checking them out.
It is possible to plant potatoes in August for harvesting later in the year for Christmas dinner. Buy seed potatoes sold as Christmas or winter potatoes and I find they are best grown in containers so that you can bring them into a greenhouse to protect from frost. These potatoes do not need to be chitted before planting.
Plant into the container in the usual way and the best time is late August /Early September. Use the same type of container and compost as you would normally, water in dry spells direct to the plant avoiding as much as you can the leaves, as that antagonizes the blight which can be around late September/October if it is warm and wet.
The top growth is frost sensitive so you will need either to protect with a fleece or bring under glass into the greenhouse. These potatoes will be ready to harvest about 12 weeks after planting.
Potatoes are an ideal container crop. As with all container grown plants or vegetables, because they are in a container they need a little more attention in terms of watering as they are more vulnerable to drought and drying out.
When to Harvest Potatoes
Check once the plants are flowering, this is a sign the crop is ready. If you have planted in the ground take care when you harvest not to spear the potatoes with the fork and to clear them all out of the ground, including the tiny ones, to prevent week seedlings growing the following year.
Earlies can be lifted as soon as the flowers appear as can salad potatoes.
Maincrop can be left in the ground much longer even after flowering. Towards the end of the season cut off the top growth from maincrop, leave for about 2 weeks and lift and store somewhere cool and dark. Hessian sacks are good for storage as they allow air circulation.
There are a vast amount to choose from in the garden centres and seed catalogues including many well known names available such as Maris Piper, King Edwards Charlotte.