growing potatoes organically: when and how to plant, hill and harvest

hilled potato plants in raised bedA FRIEND I BUY seed potatoes with and I were scratching our heads as we filled out the order form, blanking on the line where it said “preferred ship date.” How early do we want them to arrive, we asked ourselves as we do every year. Time for a review of that and other questions about when and how to plant, hill and harvest potatoes. (That’s a row in my raised beds here, seen in late spring one recent year.)

Many companies ship extra-early, based on rough frost-date estimates for each area that may not be exactly what’s going on at your place, but is that really when I want the starts to arrive? I asked for advice from Alley Swiss of Filaree Garlic Farm, a longtime certified-organic farmer in Okanogun, Washington, whose main crops—garlic, shallots and potatoes—are favorites in my garden, too.

(You might recall the popular garlic-growing Q&A Alley and I did together, and our later garlic-growing piece in my column in “The New York Times.” I’ve learned a lot from our ongoing conversations–including that it’s OK to wait a little while for the seed potatoes to arrive.)

potatoes dug from the garden

how to grow potatoes, with alley swiss

Q. When is the right time to plant—is there a cue in nature to remind us, or a soil temperature or calendar date we’re looking for?

A. At the earliest, I recommend planting two to three weeks before your average last frost date. Seed potatoes can rot if planted too early in cold water-logged soil.  If your potatoes do get a heavy frost after they emerge, they will put up new shoots, but every time they die back they will produce a smaller and later harvest.

I like to wait for the soil to warm up a little at which point they emerge quickly and grow steadily without stress.  Late March to early May is a good time to plant potatoes in the northern states.  In the warmer areas of the South they can be planted in late fall or early winter.

Where I farm the local point of reference is to plant your potatoes when the snow is almost melted off the mountain.  Whether it’s the first dandelions blooming or a particular bug emerging; if you talk to gardeners where you live they will probably have a local reference, too.

Q. Sometimes when seed potatoes arrive, some are nearly a tennis ball and some are mere eggs.  Should I cut the larger ones up, and do I have to let them callus before planting if so?

A. Many people choose to cut their larger sized-seed potatoes into pieces.  The advantage of doing this is your seed will go further and likely produce a higher overall yield.

If you do choose to cut your larger potatoes, make sure and leave at least two “eyes” for every piece. Use a clean, sharp knife to cut the potato into several large pieces shortly before planting.

Leaving the cut pieces in a cool and humid space overnight will give them enough time to callus before planting.  The callus will help prevent infection from soil contact.

We plant our seed potatoes whole to minimize worm damage.  If you have problems with wireworms, maggots or other pests, planting whole potatoes may be a good idea. Pests are attracted to the juicy exposed flesh of a cut potato.

Q. I have read so many variations about soil prep for potatoes. Is there something they do want, and anything they don’t? (For instance, I’ve read to avoid using manures on the potato bed.)

A. The ideal soil for growing potatoes is a loose and deep loam that holds moisture and also drains well.  Luckily, for those without “ideal” soil, potatoes are hardy and adapt well too many difficult soil types.  Lots of organic matter is recommended for the best yields. It is best to incorporate organic matter or compost into the soil in the fall so the soil has time to balance the added nutrients.

Fresh manure can activate the pathogen “scab,” which makes for unsightly, yet still edible, potatoes.  For this reason I use only well-composted manure when preparing soil for potatoes.  If you do not have access to composted manure, a well-balanced fertilizer can be used (I use an organic 4-2-2).  Too much Nitrogen will delay root production and you may end up with huge plants with little potatoes.

Q. So I’m ready to plant, following your above prep guidance. Now what? Proper depth and spacing—and is it the same whether a big baker or a smallish fingerling?

A. Dig a shallow trench about 6-8 inches deep. This can be done with a rake in loose soil, but you may need a shovel or hoe in heavier soils.

Place cut potatoes 10-12 inches apart in the trench. If larger potatoes are planted whole they will produce larger plants and should be given a little extra room, 12-16 inches.

A spacing of 36 inches between rows in adequate but if you have the extra space, further spacing will make hilling easier.

Fingerling and other small potatoes can be planted closer, but no less than 8 inches between plants.  Cover the plants with about 3-4 inches of soil, leaving the trench partially filled.

Q. The hilling thing is probably the most confusing part (and the most work). When and how deep and often do I hill, and where is all that extra soil meant to come from? Can I use straw or composted leaf mold or some other “mulch”?

Potatoes hilled a second time, with straw
A. Hilling is the most crucial, tiring and fun part of growing potatoes.  When your potatoes reach about 8-10 inches high, bring soil up around the vines from both sides.  This can be done with a rake in loose soils. If your soil is hard, you may need to cultivate the soil before raking or use a hoe.

Make sure not to cultivate too closely to the young plants as to not disturb the new roots systems.  Hilling brings loose soil around the vines where the potatoes will form as well as deepening the roots into cooler soil.  With the first hilling, I like to cover the vines up so that only the top leaves are exposed.  This allows for a shallower second hilling done 2-3 weeks later with an additional 2-4 in of soil brought around the vines.

A mulch that is loose and allows the soil to breath can be applied after, or instead of, a second hilling.  I recommend straw [above photo, a second hilling of straw in Margaret’s garden] because it breathes well, but leaves can be used as long as they are not applied too thickly.

A good layer of mulch can help protect vines from potato beetles by creating a barrier as well as providing habitat for insects that eat the beetle’s larvae. The fun part of hilling is looking at your beautifully hilled rows when you are done!

Fresh-dug early red-skinned potatoesQ. What’s the above-ground signal for when it’s OK to harvest new potatoes? Do all varieties offer this possibility?

A. Potatoes begin to produce tubers after flowering.  Several weeks after flowering, dig into the loose soil at the sides of the vines and you shouldn’t have to dig deep to find thin-skinned new potatoes.  These can be pulled from the plant without harming the development of the still maturing potatoes.

The waxier-textured potatoes are best for immature use.  The variety ‘All Red’ makes for a colorful new potato with bright red skin and a pink streak through the flesh.  ‘Yukon Gold’ is another early maturing variety with great flavor.

Q. How do I know when the crop is done, and how long can I leave them safely in the ground after that?

A. Potatoes are ready to harvest when their vines die back and they lose most of their color.  This can occur with a frost or simply when they have reached full maturity.

I like to mow the vines a few weeks before harvest.  This helps toughen the skins for good storage.

Potatoes can be left in the ground for several frosts, but should be harvested before the danger of a heavy frost that could damage the spuds lying closest to the surface.

  1. Amanda says:

    After the potatoes are harvested how do you care for them? I planted Norland Red’s and Kennebec’s I live in Mass and have never grown potatoes before. I have read a few articles but all of them differ in advice. Some say don’t wash them and leave them in the sun, then another says put them in a dark location…..lol I’m so confused….help!!!

    1. margaret says:

      Hi, Amanda. No washing. No sunshine. Let them dry slightly just after you take them out of the ground (I usually leave them in my garage that morning or for the day; again not in the sunshine) then they want humid (like 80 or 90 percent) and 50 or 60 degrees for a couple of weeks to cure, then even colder after that for best longterm storage, and dark (40 or even slightly cooler). Details.

  2. emily stanton says:

    somehow time slipped away from me and I have not yet done my 2nd hilling. I haven’t been so lax in the past so I wonder what will happen if I do it now? The plants are quite large (I live in western MA) and there are some getting into flower. They are a good 18″ tall.. what should I do?

        1. margaret says:

          Hi, Kristina. Typically here in Zone 5B, where frost comes typically around early October but can some as early as mid-September and as late as late October, I harvest in September sometime. Of course I have been pulling potatoes as I want them from “new potato” stage on (from midsummer) with some varieties. Other than on “new potatoes,” the vines should have died down, giving you a signal that anytime after that is good. At the end of this story the expert grower gives more tips.

  3. Rebecca says:

    I had good luck this year growing both sweet potatoes and blue and red potatoes in large smart pots. I am going to do a second planting of regular potatoes now that it is cooler here in South Carolina. I mixed a little peat, composted manure,and garden soil. It worked great. The pot was filled to the top with the sweet potatoes. It was a little warm (actually hot) for the other potatoes but they did manage to produce pretty well, especially the blue. Thanks for all the tips. I will also try them in the ground if I can find some room.

    1. margaret says:

      Thanks, Rebecca, and nice to see you here. Jealous that you can do more potatoes! We are shutting down for the winter up here. :)

  4. Bob says:

    I never email, but I was just thinking yesterday about requesting a primer on potatoes!! Had moderate success last year with my first attempt, but I planted varieties that were all easily (and cheaply) available at the grocery store. They were however better tasting and so crisp, which was a nice surprise! Looking to venture out a bit this growing season!

  5. Deb says:

    I tried planting my potatoes in the “potato boxes” last year. Didn’t get any potatoes that were higher than the ones at ground level. Of course the boxes were about 3-4 feet high so shoveling dirt all summer and getting a handful of potatoes was a big disappointment. Any ideas or suggestions? Thanks.

    1. margaret says:

      Hi, Deb. I have felt the same way…not a big fan of “bins” or “boxes” so I just do it the old-fashioned way. Watering, in particular, is very tricky in a tall container full of soil, and I never get as good a result.

  6. Linda says:

    I grew up in western Mass. My Dad planted potatoes every year for as long as I can remember. They lasted the entire winter. They were the best! My sister and I had the job of picking potato bugs and dropping them into recycled tin cans half filled with kerosene as the plants were growing. Dad never had to use any pesticides. We were not overjoyed with this task as you can imagine. But in retrospect, I have never tasted a potato as good as my Dad’s. We especially loved the first tiny new potatoes boiled with their skins on and topped with melted butter. Thanks for the memory.

  7. Jill Bressler says:

    I’ve been growing fingerlings for several years until I got a potato beetle infestation. It was quite a shock to walk into the garden and see the potato vines covered with the bright orange-red bugs. I asked at my local nursery and was told that I couldn’t grow potatoes again for 3 years to starve the larvae (which also attacked my eggplants but not my peppers or tomatoes). So I skipped last year. I’m willing to wait it out, but I’m wondering if you have any suggestions that could lessen the time.

    1. lori says:

      Nonsense, you can keep growing those potatoes! Those bugs will come back no matter what you do so don’t stop growing, just get picking. We pick off the bugs into a bucket of water. It doesn’t take long to lower the beetle population by this method. You’ll never be rid of them unless you spray…and for heavens sake, don’t do that!!! You can live in harmony with nature by planting beneficial insect attractant plants around your potatoes as well. This won’t eliminate the dreaded little monsters, but it will keep them in balance.

    2. idana crowe says:

      I use food grade diotomatious earth for many garden pests including potato/squash/cabbage…bugs, beetles and caterpillars, I sprinkle it on leaves and stems not flowers because I don’t want the bees to get in it, keeps most pests at bay

    3. Holly says:

      The diatamus (sp?) earth works well. I also have found certain insects like some of my plants year after year. I rotate my beds yearly. I also plant oregano in with tomatoes, and eggplants. I plant my onions and leeks in my rose bed. It prevents fungus and insects of the roses and the onions get huge from the soil in those beds. I use copper strip around my cabbages, and put marigolds in the potato bed. You can also order ladybugs and my faviorte –praying mantis to control the insect population. If you keep out water for birds, you can also attract dragonflies which are voracious insect eaters! I have a swarm of 20-30 Verigated Darners every year that love my blackberries for the tasty ant and Beatle populations. :.)

  8. Tina says:

    Great timing: just returned from Capital District (Troy) flower and garden show with a few pounds of interesting varieties of potatoes from Landreth’s (now in NYS). We can plant a bit earlier here in CT, but any tips on how to best keep my little potatoes safe and viable between now and sometime in April would be appreciated. I should have asked at the Landreth booth, but was having too much fun perusing their seeds and tubers and forgot!

  9. Terry says:

    Suggestions on watering would be helpful. Drip versus sprinkler, when and how much? You would think I know as I am from Idaho!

  10. Mimi Alexander says:

    I live close to Tulsa, OK. I notice most of your posts are pertaining to the, cooler states of New England, and upper northeastern states, which do not apply to my growing area. I plant my new potatoes the end of March in a rfaised bed. My problem in growing potatoes is that once they are ready to harvest, I have no where to store them. We do not have a cellar or basement. Our summers are way too hot and storing them outside would be terrible. Can’t store them in the house because we use an airf conditioner which is set at 72 degrees and that’s too wrm to store potatoes in any dark closet. So please advise me on where and hbow to store potatoes after harvesting in Tulsa, OK.. Appreciate your comment and suggestion.

    1. margaret says:

      Hi, Mimi. Doesn’t sound as if you have the ideal spot — which would be 45-ish degrees and like 90 percent humidity (even a little cooler is OK, but like 40-50F). So I have to say I would be tempted to leave them in the ground, heavily mulched, since if they have been hilled a couple of times (and then mulched) the tubers should be nowhere close to the surface, and the soil and hilling and mulch may provide better insulation against heat than you can find in your house. Another tip would be to grow later-to-harvest types (sometimes referred to as storage potatoes) and plant them later so that you are not harvesting till late in the year anyhow, growing only the number of early to harvest “new potatoes” that you can use during the summer months, so storing is not at issue with those.

      1. Allen Marlow says:

        OK, but really, who has a walk in cooler set to 40-45[degF] with forced 90% humidity in which to store their potato crop? In SE Michigan, my basement “pantry” runs about 60[degF] in Nov/Dec, 50-ish in Jan/Feb, back up to 60 toward the end of winter. And the humidity is sub-50%.

        The temperature of this space I cannot affect, really. It is a function of outside cold, and depth under ground. Humidity, though… how can I up the humidity, even in a smaller area/volume? I’ve thought creating an enclosed area, not too tight, with bits of plastic sheeting, then placing a re-fillable water tray beneath the potato bins perched above. This tray would be sitting right on the bare concrete floor, the coolest place in the house, so evaporation would be very slow. Would this work?

        I guess I also am curious (being an engineer)… which is more important, lower temp or higher humidity? and what does each contribute to longevity of storage? does either affect flavour, texture, sugar vs. starch content through the winter months?

        Curious minds want to know!


        1. margaret says:

          I can only speak to personal experience based on years of very unscientific experimenting, and I have had my best, longest-lasting stash when I keep them cold. I don’t have the ideal humidity anywhere, either. But 60F is just too warm for good storage.

          I was interested a few years ago to realize that pretty far into the winter that the upstairs of by barn (insulated, with a very small amount of electric baseboard heat to keep it above freezing, but like 40F, not warm) was a better spot than my cellar. If we have sustained single-digit spells I turn the little baseboard up a tiny but to try to stay at 40ish or so.

          If I can keep animals out (creating a hardware cloth cage or something) the Bilco door entry to my cellar (metal doors above a staircase set into an excavated area) was also better than inside the cellar.

          My mudroom closet is colder than the mudroom itself (which is colder than the house proper), and so on. I have tried everything, and I vote for colder. Heat only hastens dehydration of the tubers, and prompts sprouting I think.

  11. Bonita Sitter says:

    Hi, the methods you describe are certainly tried and true. We have a huge garden for food and always seek short cuts if they work. Have used Ruth Stouts method for years. We work compost into the soil, toss the potatoes randomly on top, scatter a few inches of hay, straw, whatever we have on top, water during drought, come back at the end of summer to harvest by pulling off the cover. Oh, it’s easy to snag new potatoes along the way also. I store them in an insulated room in our garage warmed by an old crock pot, which can be adjusted higher or lower depending what WI winter throws our way. As I age, yes, 60, I so appreciate Ruth’s methods. We have snow today, so not much hope of planting for a while, thanks.

  12. Jenny says:

    Hi, thanks so much for your helpful info on growing potatoes! We live in Northern Indiana and have been growing heirloom potatoes (red, Yukon gold, and russet) for about 4 years now, meaning I save seed potatoes from the previous year and replant for a new crop. I noticed last year that my plants looked great, and I have always followed the hilling process that you mention also, but when I went to harvest, my potatoes were smaller and didn’t yield as much as they should have. Is it time to just get new seed potatoes, or should I add some straw to our sandy soil? Any suggestions would be appreciated! Just trying to plan ahead! :)

  13. Jim Mathwig says:

    Thank you all for your thoughtful questions and comments. This is really helpful. We are in snow country where the 90% chance of no frost is may 22nd, but we have had a hard frost as late as June 7 and as early as August 29–yes in California. It has been unseasonably warm this winter, only getting down to 22 or so. With all the sunshine I planted potatoes on April 1st, We have always used organic potatoes rather than “seed potatoes.” Is there a difference or a reason? This time though, I discovered after the fact that the ones I planted might not be organic, so could have been sprayed with the retardant. Ugh. I don’t know if I should dig them up and replant or just see what happens. Thoughts?

  14. Lon Samuels says:

    Nice article on potatoes; thanks for posting.

    Here’s a technique that I use for frost protection…
    If frost threatens the newly emerging potato plants, simply take a hoe and pull soil up over the plants. That’s a quick and easy way to keep the plants from being damaged by frost; assuming the shoots are still small enough for this to be practical. This “emergency hilling” can be left in place; the plants will re-emerge through the soil within a few days.
    A quick covering of mulch over the plants is another option that will usually provide enough protection from frost.

  15. Traci says:

    First time growing potatoes and my plants are just starting to flower. Do I keep watering as the tubers mature or water more or less often?

  16. Chrissy says:

    I ordered fingerlings and purple potatoes from my seed catalog about 2 months ago, along with some heirloom tomato seeds. I received the potato seeds about 1 month after ordering them (I live in NEPA), opened the box to look them over, and then closed it up again, basically forgetting about them. I’ve been dedicating so much time to taking care of my tomato seedlings, that I completely forgot about the potatoes. Until today. When I opened the box, I found the potato seeds had sprouted thin roots (tubers?) about 8 inches long. Are they still okay to plant?

  17. Deirdre says:

    So I’m a vermicomposter and have after 2 months been able to identify the crazy plant growing in my compost bin as potato, mostly because it just started flowering a few days ago. My compost bin is an old garbage can that the potatoes took over one half of. I live in Sacramento CA, any suggestions on what to do with this beast taking over my compost bin and still be able to use the other side for my vermicomposting? Or do I have to pick one or the other?

    1. margaret says:

      Hi, Deirdre. I don’t know. Seems like it will be a real-estate grab — the potato will want the whole garbage can, no? I can’t picture tossing raw materials onto the potato all season long till harvest time — just seems logistically messy in such a tight space. No doubt that the potato will keep on trying to grow, but won’t it just make your composting a challenge?

      1. Deirdre says:

        That is where my challenge lies….and this is the first time in 6+ years of vermicomposting I’ve had this conundrum. Currently both seem content, but I’m so torn. I love home grown foods and I love feeding my worms my green waste…. I’ve recently moved to a diet that is 75% fruits and veggies which is making my worms happy for more food, but this potato plant, who I’ve named Seymore, is bigger than any other plant I EVER tried to grow.

  18. MIKE BOUCHARD says:

    I live in Western Maine and I plant my potatoes just a bit before the 4th of July. I plant them late to let the potatoe bugs go to my neighbors first. I get the second round of them but they are easily picked off by hand. Even planting this late I still get good sized spuds. The secret is lots of well composted manure hay grass etc…..

    1. margaret says:

      Good point, Mike. A shift in timing of when we plant things can help minimize pest issues — with squash, for instance, too. Thanks for saying hello.

  19. Bob says:

    I have been growing vegetables in my garden for our sustenance, for many years now. One item readers may find that works well for me is this: Leave your root vegetables such as potatoes in the ground over the winter. I live in Canada where winters are severe. I have always left my carrots, beets, potatoes in the ground. Now then, that said, the secret is to MULCH the rows with organic stuff. I use the leaves of the trees in our yard to cover the vegetables deep enough to prevent the frost from permeating the ground. I mark the rows with tall sticks in order to find the vegetables when we have 3 feet of snow. We dig up only what we need and move the stick to the point we stopped digging. Never had a problem with moles or mice. Our garden lasts us until the spring. Then we start the process all over again.

    1. margaret says:

      Thanks, Bob, for sharing your secrets. Lucky you no voles and mice…some years they don’t even wait here until fall to start “harvesting” the underground goodies. :)

  20. Jim says:

    I had a great harvest of potatoes around the 4th of July. Now I’m thinking, is it too late to plant a second crop? I live in North Alabama and would really like to have a crop in October/early November. Provided I can find some to seed potatoes, how do you think they would do?

  21. Cailean Campbell says:

    This is the first article I have read about planting potatoes, and as such, I have made several mistakes (according to this article). I live in a second floor apartment with a small (8′ by 4′) east facing balcony. I live in Colorado Springs CO at about 6000 feet. With all that being said, is there any way to plant potatoes in a pot instead of ground?

    1. margaret says:

      Hi, Cailean. You can grow potatoes in containers, but I recommend a BIG container (think whiskey half-barrel, not plain little flowerpot). You could even use a “grow bag” (big fabric bag) or an old trash can with holes punched for drainage, etc. BUT: You need sun, and you say east-facing balcony — how’s the light?

  22. Tom Johnson says:

    I grow my potatoes in a grow bag. The plants are huge this year. I’m noticing what looks like cherry tomatoes after the flowers die off. What gives?

    1. margaret says:

      Hi, Tom. They are the inedible fruit of the potato plant, and some varieties are more inclined to produce them. Iowa State says that ‘Yukon Gold’ does so more than many varieties, for instance. Don’t try to save the seed from them to grow potatoes, and again: don’t eat them!

  23. serrill flash says:

    I have visited the cornell website concerning leek moths. This is year two for me and onions and garlic have been hard hit. I am not expecting to plant any more allium. Any thoughts on effective strategies? Dipel (considered organic?)

  24. Michael says:

    I am a new gardener. Never have tried to grow vegetables before but I am willing to learn what ever it takes. One of my questions is how often am i supposed to water the potatoes? In this case how much water do vegetables need in general? I just got a greenhouse and I am going to start growing different vegetables but definitely potatoes.

    Thank you

    1. margaret says:

      Hi, Michael. I water with sprinklers (oscillating “fan” types, set to a medium-low height, but “leaky pipe” soaker hoses woven through your beds or drip irrigation would work, too. I try to imagine that I am simulating a weekly inch of rainfall, so I use a few cheap plastic rain gauges around the area, and move the sprinkler down the row once I see enough “rain” in the gauges until I have slowly saturated the entire planting.

      This usually means moving the sprinklers every hour or two down the row, and I do this once a week unless the heavens provide. Not a precise science because I don’t have an irrigation system, but it works. Our job as gardeners is to fill in where the clouds don’t.

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