Do you want to know how to grow a really good crop of potatoes? This article is the definitive guide!
Growing potatoes can be summarised in the points below:
- To begin you should remove all weeds, grass and other green foliage from the soil.
- Next you should dig the soil over at a depth of 6 to 8 inches, ensuring it is finely cultivated.
- Form a drill by marking out a line with string and then place each seed 14 to 16 inches apart along the line.
- Now you should cover them with around 6 inches of soil over the top of the seed- you can do this by shoveling soil from each side of the line- this will form a valley on either side, which will be useful for drainage.
- Spray the drills for weeds before the plants emerge, spray them for blight when there is a blight warning and harvest them when the green leaves wilt and die.
- Harvest when the weather is dry.
That is the most basic explanation of growing potatoes – There is a lot more to it than these few points but it gives you an idea of the basic steps.
This article is going to be an in depth article, which i will go into detail about each step. You can use the article index to quickly navigate to your chosen subheading.
What are potatoes
Potatoes are a starchy, tuberous crop from the nightshade family of perennial plants Solanum tuberosum. They grow in the ground (also known as tubers) below soil level and the leaves of the plant above the soil. At harvest you will find there are usually 10 to 15 tubers on each plant and when fully grown they range in size from 2″ , 4″ or 6″ in round or oval shape.
The origins of potatoes
Wild potato plants were initially discovered in North and South America. The first domesticated plants originated in what is known today as Peru between 7000 to 10000 years ago.
Who discovered potatoes
In 1536 Spanish Conquistadors conquered Peru and brought it to Europe where it was spread throughout the rest of the world. These men did not discover the potato as the Peruvians would have been using potatoes for 1000’s of years, but they were responsible for introducing it to the rest of the world.
Why are there so many different varieties?
Since that time they have been bred with other potato plants to achieve different goals in a quest to improve them. As each variety was introduced to a new part of the world it would encounter new challenges with different soil, climate and disease. This created new varieties and today there are literally thousands of varieties each with their own unique characteristics.
Are the leaves of a potato plant poisonous?
As it belongs to the nightshade family- if you were to eat any green part of the plant such as the stem, leaves or flowers, a toxin called solanine found in these green parts would be cause you to become ill. Solanine is harmful to human health. This same toxin solanine can also be found in the tomato plant.
How to grow potatoes
Before planting our potatoes into the soil we should check a few things first. The soil should be free draining – ie: it doesn’t hold water, it should be free from green organic material such as weeds and grass, it should be finely cultivated and it should be rich in nutrients.
The location of the potatoes should have access to sunlight and allow wind or a breeze to blow through. This will help to prevent potato blight which can ruin your crop in a matter of days. So keep away from under hedges or other very sheltered places if possible. The wind and sunlight work to dry up blight which thrives in very humid conditions.
Preparing seed potatoes
As with most things, you only get out what you put in, as this is no different with seed. You should plant the best seed you can get your hands on.
Selecting the variety of seed potatoes
If you are going to grow your own potatoes you probably enjoy eating them and you may already have a favorite variety – this is helpful as it answers the first question of which variety to plant. I have an article explaining the different varieties in detail. “the best-tasting potatoes to grow“. You need to know which variety you are planting because each variety has its own recommended planting date and harvest date.
You should now research where to buy the “best” seed available for that variety. What is meant by the word “best” is actually how many times that variety has been planted previously.
You should try to buy certified seed – this can be bought online or from a farm shop. The certified seed means that it has been inspected by a potato inspector and he has checked the records that it has not reached the maximum number of times it should be planted.
The problem with using uncertified or old seed means your potato crop will not be as good as with new or certified seed. Not as good means it may have had a disease/virus transmitted to it in the past, the yield or numbers of potatoes expected will be less, and the potatoes may be misshapen and not as good to eat.
Preparing seed potatoes for planting
So you have picked your variety and bought good quality seed, now you should prepare it for planting.
What is a good idea to do is to chit the seed, to give your potatoes the best possible start when it goes into the soil.
Chitting seed potatoes
Chitting the seed means you are placing the seed into a well-lit outdoor shed which is slightly warmer than the outdoors a few weeks before you intend to plant them. This warming of the seed makes the seeds think they are ready to grow again and so they begin to produce a chit or bud. See articles, How to get potatoes to sprout eyes or How to plant potatoes from eyes.
It is important to keep a check on the potatoes at this stage because you don’t want this chit to get longer than 3-6mm (1/4″ – 1/2″) as it will be vulnerable to breaking off and thereby deeming the whole process invalid.
The other thing to watch is that the chit has access to plenty of light. A chit formed in the dark will be white and fragile whereas a chit formed with plenty of light will be green and soft and much more flexible and less likely to break.
The seed potatoes are now ready for planting into the soil.
Aside from planting your potatoes into the ground, there are many different vessels you can choose to plant into. See Choosing where to plant potatoes for inspiration. Some people grow them inside tyres, raised beds, large sacks/bags and even growing potatoes in a bucket. The main point to make about wherever you choose to plant your potatoes is that you allow each seed enough room to fully develop.
If you have no space outside to grow your own potatoes you can grow them indoors –How to grow potatoes indoors.
Early potatoes should be in the ground by end of March, see When to plant early potatoes. Mid-season potatoes by end of April and Maincrop should be planted by end of June. The later in the year you plant the later you harvest. See the article How late can you plant potatoes for more.
One seed potato should have a minimum of 10″ of clear growing space around it. If you plant more than this inside this space you will have more in number of potatoes but they will be tiny. It is far better to have less potato plants in your alloted space, and produce a decent crop of much more useful larger potatoes.
Potatoes like soil rich in nutrients. If your soil lacks nutrients you will have a poor crop. I always advise adding some potato fertiliser or farmyard manure to the soil when planting potatoes. You can do a soil analysis at home which is useful as it prevents the 4 monthly expectations of getting a nice crop of large potatoes vs. the reality of a few marbles if the soil does not enough nutrients. See What is the best fertiliser for growing potatoes and for those who like to make their fertilizer mixture at home see Homemade fertiliser for potatoes.
Weeds in potatoes
The crucial time to prevent the onset of weeds is before the potato tops come through the ground. This is a time slot known as pre-emergence.
You must have not weeds present when the potatoes are coming through the ground as they will compete with the potato tops and can either overcome the potato plant and kill it or hold back its development and act as a thief taking vital nutrients away from it.
You can use mechanical methods such as moulding/hilling up the drills or soil or use chemical methods such as using a pre-emergence herbicide. See What to spray potatoes with to control weeds
Potatoes require watering as much as they need fertilizer – all you need to confirm this fact is to drive by a large potato field in the middle of summer to see the irrigation equipment constantly watering the valuable crop.
Depending on the annual rainfall for your area you will need to check the soil often. This ensures that it doesn’t completely dry out but also that you don’t overwater, as this will also damage the development of your crop. See How often to water potatoes for a more in-depth discussion.
Potatoes thrive in sunny conditions and their growth will be hindered if the plants are placed under a large tree or tall hedge which blocks out the light. See How much sunlight potatoes need.
There are other benefits to the potatoes getting sunlight, such as drying up and killing blight spores on leaves. If your potatoes are under a tall hedge or tree this will not only provide shade from sunlight but it will also prevent a fresh wind from blowing through the leaves of the plant.
It is beneficial in times of damp humid weather (which are optimum conditions for potato blight to occur) that you get your leaves dried up as soon as possible to help prevent the spread of the blight.
Hilling / moulding potatoes
Hilling or moulding up potatoes is a practice of adding more soil to the potatoes as they grow. This is to prevent them from bulging up from the soil they were planted in, becoming exposed to sunlight and then being dumped.
If you plant your potato 6 to 8 inches into the soil there is not much need for the practice in reality. People used to plant their potatoes less deep so they would emerge sooner, and then they would add extra soil later in the season to ensure the crop would not show through.
In theory, this means the potatoes would be dug sooner but it is nothing worth talking about. A better reason for the mould up for farmers using a drill plough was to cover the weeds with soil as the potatoes were coming through the ground, thereby removing the need for a pre-emergence weed killer. See How to Hill up potatoes for more.
Potato late blight
The main disease you need to be aware of during the growing season of potatoes is blight. This is a fungus carried in the air and will destroy your entire crop in a few days if left unchecked. See What blight look like on potatoes.
You should be prepared to spray a blight preventative fungicide spray once every 5 to 7 days. You can buy a spray or you can make your own – Homemade potato blight spray
For an depth understanding of this devastating disease see What causes potato blight.
Ending potato growth
When you have successfully grown your potatoes to the size you prefer, you should “burn them off”. This is a process of spraying the tops with a specified herbicide so that they die. This prevents the potatoes from growing any larger and also so the tops cannot be attacked by blight.
A common chemical used in this process is called Reglone. It is sprayed onto the potato tops and within a day you will notice the leaves turning brown and dying back. It has no effect on the soil.
After the tops of the potatoes have died back and are brown – either by chemical or natural process- you should wait two weeks before harvest.
The two weeks after growth is “setting the skin” This is the natural process of toughening of the skin on the potato which makes the potato less susceptible to disease in the store. Harvest time is very important to potato growers.
When harvesting early potatoes they are eaten as soon as they are dug, but for main crop or potatoes intended for storage, you should let them sit in the ground for some time – two weeks after growth has ended. A detailed discussion on harvesting periods for potatoes is covered here When to harvest potatoes.
Potatoes should be stored in a cool dark room, not too dry and not too humid, too dry will dehydrate them, and too humid will promote disease.
The store should be cool but not refrigerated or frozen as this will damage the potato. If the store is too warm it will also dehydrate the potato and promote disease.
The store should have a good airflow through it to also help prevent disease and mould, the store should be dark to prevent the potatoes from turning green – caused by time in sunlight. I have a helpful article titled How to store potatoes from the garden.
There are many pests and diseases to be found in a potato crop. I will list the articles I have completed so far and add to the list in the future.
I hope you have found my article helpful- please comment below if you have. Thank you- Richard.