How To Grow Potatoes
Growing potatoes is not difficult to do, but does involve significant work at the beginning preparing the potato bed, and at the end harvesting the crop and clearing up. A task not for the faint hearted!
Despite all this effort, growing potatoes is tremendously rewarding. It's hard to beat the satisfying feeling of wheelbarrrowing home a successful crop from the allotment, knowing that the harvest can be stored and used as a staple food to feed your family through the cold winter months. The same method can be followed for all types of potatoes: early, second early, and main crop varieties.
All types are planted at about the same time of year, the difference is that early varieties mature quicker and require a little less space between plants.
How To Grow Potatoes - Introduction
Having a healthy back is a very good starting point to planting potatoes. Potatoes like a well dug soil, and the ideal approach is to spend a few hours digging trenches for a potato bed. This effort has a number of advantages. It breaks up the soil and allows young potato tubers to form without being mishapen by lumps or large stones. It buries all weeds that may be present in the potato bed. And, of course, it is excellent exercise after a winter rest!
There are alternatives to this hard work. It's possible to grow potatoes in a large container like a big pot or a barrel cut in half. I am told this works very well and seems less effort than the method I describe here. The disadvantage with the pot approach is that it does not scale without becoming expensive. To grow a lot of potatoes you would need to have a lot of pots and a lot of soil. Nevertheless, this is a good approach for a kitchen gardener wanting to sample the delights of freshly grown new potatoes for occasional summer suppers.
How To Grow Potatoes - Sowing
Early spring is the ideal time to plant potatoes - at least for where I live in the South East of England. The tradition is to plant seed potatoes either side of the Easter weekend. The exact date of Easter changes from March to April and this can be important as potato plants are damaged by frost. An advantage of deep trenches (around a spade deep) is that it allows seed potatoes a growth period below the ground after which any risk of frost has usually passed. The deep trench is also an ideal space for the potato tubers to grow in.
How To Grow Potatoes - Varieties
All varieties are planted at the same time of year - the difference is the speed they grow and when they are to be harvested:
- First Earlies
From sowing to harvesting this is can be as little as ten weeks. They can be planted in trenches about 30cm or 12" apart and with 50cm between the rows. They are harvested when the plants are about to flower. Start by digging up one plant, and if the potatoes are of sufficient size you know they are ready.
- Second Earlies
Second earlies take significantly longer to grow - around 16 -18 weeks - and are larger is size than first earlies. Allow a little more space between the tubers and rows than first earlies and wait for the plants to flower and wilt or yellow a little before digging up.
- Main Crop
Recommended spacing is around 40cm or 15" apart and rows around 75cm apart. Time to harvest is about 20 weeks. Main crop potatoes are the type to choose if you intend to store for winter use.
How To Grow Potatoes - Planting Distances
If you have room, my recommendation is to space the rows of potatoes apart generously. Potato plants grow big, and it is helpful to allow some space between the rows to walk down for watering and weeding. Also, potato plants do need to be earthed up, and this earth needs to come from somewhere. I find the easiest way is to 'borrow it' from the ground either side of the trench. If there is not enough space between rows there will not be enough soil to earth up with. Having space also makes a difference at harvest time. Digging up potatoes means that the displaced earth needs to be put somewhere. If it can be piled up between the rows of potatoes this makes the process easier.
There is some debate amongst gardeners about chitted or unchitted seed potatoes (a chit is a little white shoot that springs out of the seed potato). I do nothing special in this regard, as my experience is that seed potatoes naturally start to chit in their paper bag from my allotment shop in the week or two before I plant them. If potatoes have chitted, it is helpful to not break them off when planting and also to have the chits pointing upwards.
I have planted both chitted and unchitted potatoes in different years and the results have always been the same. Nature has always worked it's magic and potato shoots appear above soil level a few weeks later. I have not noticed any difference in the speed of the crop maturing or the size of the potato harvest. On this basis, my advice is to make no special effort to chit potatoes as they seem to germinate extremely easily by themselves when placed in a warming spring soil.
Once the seed potatoes are happily placed in their new home they should be carefully covered with the soil that was excavated to dig the trench - just enough care to avoid breaking too many of the chits that may already be on the seed potatoes. There is no need to panic if chits are broken, the seed potato will simply grow some more.
How To Grow Potatoes - Watering & Earthing Up
Potatoes do not like a waterlogged soil, but they will not grow to a big size without regular watering. A rule of thumb is to soak the trenches of the freshly planted potatoes on day 1 of planting, and then water once a week in hot weather or every two weeks otherwise. I've learnt the importance of doing this through experience.
One year I took the view that potatoes were extremely hardy (which is correct) and would grow big potatoes by the magic of nature alone (not correct). That year the sun shone and the rain did not fall, and the result of my decision was a healthy set of potato plants but with a harvest of potatoes that looked like small marbles. After a winter of peeling small marble size potatoes for roast dinners - a task that takes more than twice as long as peeling big potatoes - I had learned my lesson!
When the potato plants get around 30cm high this is the ideal time to start earthing them up. The purpose of earthing up is to eliminate all light from reaching the tubers beneath the soil. Potatoes turn green, and poisonous, if they have been exposed to sunlight and they must not be eaten. When storing potatoes, it is also important to exclude all light from them for the same reason. The picture below shows my technique for earthing up. I take soil from between the trenches and pile this on top of the potato trenches.
After a few more weeks, and the odd good watering, the potato plants become even more self-sufficient. Hoeing between the plants no longer becomes necessary as the plants thicken. Soon after you will see flowers, followed by the production of green berries. Like with green potatoes, the berries are poisonous, so you may want to remove them or advise children to leave them well alone. Flowers and berries are also an indicator that potato tubers are swelling below the ground, and means it is a very good time to give the plants a thorough soaking with water.
How To Grow Potatoes - Harvesting
With luck, the continuous August sunshine should make the potato plants begin to wilt and turn yellow, marking an end to their growth cycle and showing that their delicious produce below ground is fully grown and ready for harvesting.
The search for potatoes is both an exciting and anxious time. Is the unseen crop healthy and of a good size? To be frank, it is also hard and slow work. Each row of potatoes needs to be carefully excavated, digging from around the sides and each end to reach the tubers below.
I prefer to use a combination of a garden spade to dig down around the plants to the depth of where I believe the tubers should be, and then scramble through the dirt using my gardening gloves to find the potatoes. It seems such a waste to damage the crop after all the effort of growing them, but the reward of wheelbarrows full of big, undamaged, good for storing, delicious potatoes is well worth it!
If you plan to store the potatoes there is no need to wash off the soil, but it is important that the potatoes are stored dry. The ideal time to pick them is during a period of dry weather as the freshly dug, dry crop can be directly stored in blackout paper sacks or boxes.
How To Grow Potatoes - Tidying Up
The final task of the summer is to return the potato bed to a flat and level surface ready for next year. It is highly recommended to keep rotating where you plant potatoes, ideally not returning to the same spot until the fourth year. Potatoes are a hungry plant and grow best in a well manured soil. The picture below shows the old potato bed levelled and manured to recover on the left hand side, and next year's bed with a similar heavy mulch on the right. These mulches also help suppress weed growth over the winter and top soil being washed away by rain.
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