A Simple Way to Get High Yields of Potatoes

, written by Barbara Pleasant us flag

A good harvest of potatoes

It's no secret that I love growing veggies - potatoes in particular - so it upsets me that so many people are getting sad results when they try growing potatoes in novel ways. I just spent an evening watching videos of people who planted potatoes in various enclosures, grew beautiful plants, and then harvested two handfuls of small, knobby potatoes.

It was not their fault, because this is what usually happens when potatoes are given growing conditions that are much warmer and drier than would occur under normal circumstances, normal being the consistent cool, moist conditions six inches (15cm) underground. I learned this twenty years ago, when growing potatoes in towers made from old tires became a passing fad. The soil-filled black tires heated up so much that the plants lost interest in making potatoes (I harvested five), which never happens in my garden.

Potatoes in bags

The Problem With Growing Potatoes in Containers

Indeed, researchers in tropical climates have found that when soil temperatures rise above 75°F (25°C), potato plants signal their roots to stop making tubers. Instead, the plants may rev up other reproductive strategies, like developing more fertile flowers, or popping out little green potato-like organs on the main stem. Daytime heating of roots is one reason why potatoes grown in above-ground containers may fail in warm summer climates. Potatoes can take warm air temperatures, but when the roots warm up too, productivity plummets.

A second problem with growing potatoes in towers, pots or bags is the dwarfing effect caused by the containers. The plants sense that they are growing close together, which makes them produce numerous small tubers rather than a few large ones. Large containers or broad bins relieve this crowding a little, but consider: When the Master Gardeners of San Francisco, CA (a potato-friendly climate) compared the productivity of ‘Carola’ potatoes grown in beds, bins, bags and pots, these are the numbers from the final weigh-in:

Growing Method Average Yield Per Plant
Mulched raised bed 2.38 lb (about 1 kg)
Wire bin 0.70 lb (0.32 kg)
Plastic pot 0.62 lb (0.28 kg)
Potato bag 0.58 lb (0.26 kg)
Burlap bag 0.25 lb (0.11 kg)

You can follow this link to see the thoughtful work done by Canadian garden blogger Isis Loran, but spoiler alert she has not found a potato growing method to rival the hill-and-mulch method, which involves simply growing potatoes in the ground, and mounding loose soil and mulch around them each time you weed. "I loved that I could just rake up or hill up more soil & straw as the plants got bigger. It was much easier in my opinion than trying to add soil to the pallet container or rolling up the burlap bags," Loran writes.

Potatoes growing in an open-sided container

Loran gardens in a cool maritime climate like that of the British Isles, where potatoes tend to prosper no matter how they are grown. Research by the Royal Horticultural Society has found that variety does make a difference when growing potatoes in containers. When 21 different varieties were grown in 40-litre (16-inch diameter) green plastic potato bags, these varieties were the strongest producers: ‘Casablanca’, ‘Golden Nugget’, ‘Sharpe’s Express’, ‘Maris Bard’ and ‘Lady Christi’.

The story is the same in the US. In Wisconsin, potato lovers involved in the Kenosha Potato Project have found that ‘Calrose’ and ‘Charlotte’ tend to produce larger potatoes than other varieties when growth in soft-sided pots or bags.

How to Mulch Potatoes

Any biodegradable mulch is a good mulch for potatoes, though once-popular straw can be a problem because of price and pesticide contamination. I use both grass clippings and weathered leaves since that is what I have, and I especially like the way leaf mulch keeps the potatoes’ root zones cool, moist and free of weeds. A recent research project from Rutgers University showed that plants produced prettier, more uniform tubers with leaf mulch, and it’s fine to combine materials when mulching potatoes, for example by layering leaves with grass clippings. The important thing is to keep a light-blocking blanket of organic material between the shallowest tubers and the sun.

Potatoes mulched with leaves

The best time to start mulching potatoes is when the plants are ankle high and in need of their second weeding. Use a sharp hoe to nip out weeds, and then mound loose soil around the plants so the crown of the plant becomes snugged in with an additional two inches of soil. Then start layering on the mulch, and keep adding more until the plants begin to fail.

At this point you can feel around beneath the mulch for some tender new potatoes, and start harvesting all of the potatoes from your most advanced plants. As I pull individual plants, I often move the mulch to the centres of neighbouring plants that are still growing and in need of as much mulch as I can muster.

When it comes to growing potatoes, the simplest method is the best.

Barbara Pleasant

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Comments

 
"Thanks Barbara, this was super insightful for me. I have a yard where only container gardening is possible and I've tried potatoes in bags for the last two years with disappointing results. Good to know that it's not the variety I tried... Bags just aren't their thing. "
Allisen Souza on Friday 8 May 2015
"I'm so glad I saw this as I was going to try bags this year. Now I might just dig another area and do more research on growing them in raised beds. =)"
Amanda on Sunday 10 May 2015
"Great timing! I was about to start mine in bags (again though last years yield was poor and now I know why). So, seeing as I have the cloth bag specifically for potatoes, what else would LIKE growing in it that would be a good use of all the soil/space? Suggestions?"
Dani on Tuesday 12 May 2015
"Dani, plants that like warm roots are good candidates, like tomatoes, peppers, and eggplant, and possibly basil and New Zealand spinach. "
Barbara Pleasant on Thursday 14 May 2015
"I have been having trouble with some kind of worm so I am trying the bags outside the garden to try to get potatoes with out channels and other damage created by them. "
Cathy Muskus on Friday 15 May 2015
"Wonderful article - I'm growing potatoes for the first time this year using the hilling method in a raised bed. I had a few tubers left over and didn't want to throw them out so will by planting them in a few white containers (that hopefully reflect some of that heat?) - I'm not expecting a lot from the container plants, especially after reading this article - our climate in Southern Ontario does get hot during the summer - but I'll treat it as a bit of a mini experiment. I have another suggestion for Dani - it's a bit late in the season (around here, anyhow), but another suggestion for her bag would be sweet potatoes which, unlike regular potatoes, REALLY enjoy the heat "
Margaret on Sunday 17 May 2015
"Barbara, So would you suggest that I bury my Yukon Gold and Nicola pots?"
Jerry on Monday 18 May 2015
"Jerry, burying the pots will help you get some potatoes, but they will be small because of the containers....Cathy, those may be wireworms, the larvae of click beetles. They can be caught and collected by placing bait, in the form of a handful of well-soaked beans, placed in the bottom of a 6-inch deep pit, covered with a board. "
Barbara Pleasant on Monday 18 May 2015
"Barbara, how often do the bait traps for wire worms have to be checked and refurbished? Sounds like a great idea for my sweet potato patch!"
jerry on Tuesday 19 May 2015
"Jerry, it will take several days for traps to attract the wireworms, so I'd say no more often than once a week. Cut up raw potato, carrots, and other tempting foods can be used as bait -- just be sure it's in a deep, cool hole that is well shaded."
Barbara Pleasant on Wednesday 20 May 2015
"I am happy to hear this, as I am still growing potatoes in the ground. I hill my plants with garden soil which is probably why I get blight (my plants die early, but I still get a crop to last the winter) but when I have used straw as mulch, mice move in and gnaw on the potatoes. "
Patsy Alford on Thursday 2 June 2016
"This disregards the space involved with planting. At 15" between plants and 30" between rows (main crop), 100 sq. ft. would be needed for 16 seed potatoes. 2 seed potatoes in each of 8 x 12" square bags would take up 8 sq. ft. At the harvest you suggested you would need 12 and a half times the space for 4 times the crop."
Ronald Maxwell on Saturday 5 November 2016
"Yields from seed potatoes in bags can also be increased by providing the best conditions. Mix equal parts ericaceous and John Innes No 3 compost to give a ph of 5.75 as potatoes prefer acidic soil. (A lower ph makes take up of nutrients difficult). Mix equal parts blood, fish and bone with kelp for fertilizer."
Ronald Maxwell on Saturday 5 November 2016
"The methods here are really helpful. I live in inland San Diego so I wait for cool fall and winter to plant my potatoes. However, my early fall plantings were devastated by white fly left over from summer (it has been warm). I did just cut the tops off at the soil line, hoping... I treated most of my garden plot by solarizing with black plastic. Wondering if I should solarize my potato patch too? "
Linda West on Saturday 12 November 2016
"please is sweet potatoes suitable for bag growing? thought some one spoke concerning this thanks"
sunny on Friday 10 February 2017
"My experience of growing potatoes in bags is completely different to that described in this article. Yes, I had lower yields per plant than I would have from growing in the ground but that misses the point. It is the yield per bag that matters. I achieved 2.5kg of 2nd early Charlotte potatoes from one bag containing 100 litres of compost. I had a yield of 2.7kg from a single bag of main crop Sarpo Blue Danube. Each bag was planted with 6 seed potatoes, they are cheap enough so that wasn't a problem. It is a different environment and you have to alter your growing method to achieve best results. A peat free compost is best, potatoes prefer the more open stucture and it is free draining. "
Ronald Maxwell on Tuesday 5 September 2017
"Further to the above, this was the yield from the 7 bags I harvested. Bag # Potato Variety Maturity Yield 1 Swift 1st Early 1kg 2 Swift 1st Early 1kg 3 Charlotte 2nd Early 2.5kg 4 Charlotte 2nd Early 1.8kg 5 Sarpo Kifli Early Main 1.8kg 6 Blue Danube Early Main 2.7kg 7 Cara Late Main 2.0kg "
Ronald Maxwell on Tuesday 5 September 2017
"Nice Platform.Please i need a potato farmer mentor.planning to start a farm in Africa but thought i will do better having a mentor."
Kenny on Sunday 11 February 2018
"i am in Ghana , but am interested in growing irish potatoes. how do i do that since its hot here. any solution? . for now i am trying with the bags . thy have sprouted very nicely. waiting for results in a few months time."
STEPHEN EBOW TOMPORI on Tuesday 25 September 2018
"Hi, Great article. I have just harvested my potatoes here in the far North West of Scotland. Grown under black plastic and planted through a cut cross in the plastic, these Lady Balfour potatoes harvested 14lbs per square yard. For me this is a fantastic return with no weeding, earthing up or any other mulch of course. Worth a try! Seaweed and horse manure probably helped."
Malcolm on Wednesday 26 September 2018
"Just read an article on growing potatoes in bags which states that the best varieties to grow are indeterminate varieties due to the fact they produce tubers all the way up the stem rather than just at the base (which is fine if you are growing them in the traditional way in the ground). Problem is, none of the seed potato suppliers refer to this so you aren't aware of the type you can buy. As it happens, I am about to empty my first bag of Sharpes Express which I believe is an indeterminate variety so I will soon be able to see if this is true. I'll keep you posted."
Alan Corbett on Wednesday 12 June 2019
"Please do keep us posted Alan - it would be interesting to hear your experiences."
Ben Vanheems on Wednesday 12 June 2019
"Hello, I hope everyone on here is well and and keeping safe. During these uncertain times. I’m anxious to get as much out of my vegetable patch as possible. I’ve missed the boat on collecting seed potatoes but I do have a lot of walnut sized tiddlers (second earlies mainly I think) left over from last year’s crop that are sprouting. I also have a bag of supermarket Manhattan variety which are sprouting. My questions are... 1. I read that the Manhattan are susceptible to blight. Is this correct and should I risk introducing it? 2. What size crop will my tiny potatoes give and should I space them closer together? Should I plant two together? Does size matter or just the number of shoots? Thank you for an excellent site and excellent answers x"
Helen on Sunday 29 March 2020
"Hi Helen. I haven't heard about Manhattan's susceptibility to blight or otherwise, so can't advise on that. Re the potatoes that have sprouted. You may be able to plant these, though there is always a risk of disease carrying over from seed potatoes you have saved yourself. The main consideration for your seed potatoes is the size and healthiness of the shoots. I would plant them at the usual recommended spacing - potatoes grow fast and will soon bush out to fill the space."
Ben Vanheems on Monday 30 March 2020
"So glad I found this site. My husband has tried bags, big plastic pots and a raised bed for our potatoes. He just emptied a bag and the whole crop didn’t even fill a medium plant pot. There are no flowers on the remaining plants. Are we too kind to them. Please help if you can."
Jan Lea on Sunday 14 June 2020
"I have a small veg patch of around 20m squared, so yield is king! I have just lifted two of my early potatoes for a yield of 900g. Just not good enough! I have some different potatoes growing in bags, I live in hope of a better yield. I note the advice about mulching to keep the roots cool, that was new to me, thank you."
Martin Brewin on Friday 26 June 2020
"Hi Jan. It could be lack of moisture or temperatures getting very warm. I am now moving away from pots and bags - the yield is so much better in the ground. I think it's because the growing environment is just a lot more stable, with more consistent moisture at root level, which is so important for potatoes. Hi Martin - yes, mulching does help to keep the roots cooler."
Ben Vanheems on Sunday 28 June 2020
"What do we do about our plants growing too tall. Should we clip the tops? Does the height affect the production?"
Angie on Tuesday 14 July 2020
"Hi Angie. Yes, that would affect production. Do not clip the tops but instead prop them up. A few canes with string tied right around the foliage should do it."
Ben Vanheems on Tuesday 14 July 2020
"Hi everyone, yes I also have given up bags etc. as the yield has always been poor, even the late summer crop for Christmas has been disappointing. I have just lifted the first 2 Jazzy plants from my 8 x4 bed after exactly 100 days. The yield was 1.5 kilos, not much better than Martin but I do plant them close together, getting 5 rows of 4 plants into the bed. I will now dig up as required so will probably be lifting for another month (subject to the dreaded blight) at which point previous years has shown that the yield per plant will increase (I hope!)."
Alan Corbett on Tuesday 14 July 2020
"Fingers crossed for you Alan!"
Ben Vanheems on Tuesday 14 July 2020
"CAN YOU CUT OFF THE TOPS OF THE POTATOE TO GET RID OF THE FOLIAGE? WILL THE POTATOES STILL GROW? THEY ARE JUST COVERING THE GROUND AND STOPPING WATER FROM GETTING IN AND THE LEAVES ARE BEING EATEN FULL OG HOLES. HELP...."
SALOME on Thursday 13 August 2020
"I am seventy-five years of age and have been tossing my seed potatoes across my patotoe patch onto the bair ground and covering then with a aboutfoot or more of old hay, grass clippings, etc. for over thirty plus years. All I have to do when I want some pototes is lift up the hay over the area I wish to harvest and pick what I need and drop the hay back down over the aria that I harvisted from... I never till or dig... I learned to do this via Ruth Stout some fifty or so years ago....and it has never falled me.."
Nandy Nelson on Sunday 11 October 2020
"Hi Salome. My apologies - you never got a reply to your August comment. In answer to your question, though it's a little late now, I would never cut off the foliage while the potatoes are still actively growing. They are what provides the energy for the tubers to swell, so if you cut the foliage down the tubers will stop swelling. Wait until the potatoes have finished growing and you are ready to harvest."
Ben Vanheems on Monday 12 October 2020
"Hi Nandy. What a fantastic and easy going technique you've adopted. I too - for the first time - also tried this method this last growing season. It really does work and is a lot easier. I'll be switching to this way of growing all my potatoes from next year forwards. "
Ben Vanheems on Monday 12 October 2020
"Thank you so much for this article. I was anxious about growing potatoes because they take up a lot of space, and thinking of using bags instead, but I won't now, I'll use bags for peppers and tomatoes and give the potatoes some precious soil space! Really happy to have this new knowledge."
Margaret Blurton on Friday 6 November 2020
"I live in Georgia where it gets really hot starting the middle of april .I would like to know when its best to plant my potatoes and the best method since I was going with 64 gallon above groung containers Thanks so much Theresa "
THERESA Lynn HEIM on Saturday 6 March 2021
"Hi Theresa. The best time to plant is around about March, that way that can get a bit of a start before the hot weather arrives. "
Ben Vanheems on Monday 8 March 2021
"I have gardened for over 50 years. I always have had good success with my potatoes, but am experiencing something strange this year. About eight feet in one row did not produce plants. I thought something might have eaten the seed so I decided to replant. When I dug a hole to drop new seed in, I cut into tubers growing in the ground. I decided I was impatient and that plants would soon grow. However, it is a month later and no green tops have appeared."
jeanie on Saturday 15 May 2021
"Hi Jeanie, I had something similar this year. About 10 feet of two rows never came up, and the rest of the entire potato area was somewhat spotty. This was the first garden at our new downsized home; so I thought it was poor soil and a late start. Your similar experience has me concerned for next spring. Melons and corn were disappointing, while peas and beans did well. Thank you Nandy. I had forgotten about the Ruth Stout method. I tried it in 1980, got great results, but then moved into a place with no garden space. I forgot about it when I began growing again. Will definitely use it next year. "
Jimm on Friday 19 November 2021
"Some of you who are interested in growing potato’s in buckets, may be interested in this video. It was a single seed potato challenge on you tube to see who could grow the most potato’s from one single seed potato. First part of video is how they grew the potato’s the second half is the results, the potato variety was Picasso, think you will be surprised at the winning weight Cannot post link but if you search you tube for The Single Seed Potato Challenge 2022"
Derek(Delboy) on Saturday 17 December 2022

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