Wednesday, September 23, 2009

Potato Buckets: Experimental Yields

This spring I planted German Butterball potatoes in six plastic buckets. There have been reports of incredible yields from mounding potatoes exceptionally well. Claims of one hundred pounds harvested per pound of seed potato have been rumored. That kind of yield seemed fantastical to me, and other apparently rigorous scientific reports contradict such claims. Still, I wanted to try the experiment of potato mounding for improved yields for myself. I decided to trial late season potatoes, and each of the six buckets got just one seed potato each. I weighed the six seed potatoes together before planting, but not until I'd planted the fourth seed potato did I think to weigh the individual pieces. So I marked the weight of the last two seed potatoes on the buckets they went into.

First, a little background on what I might have expected from "normal" potato planting in terms of harvest yields. I'm told that a good commercial potato grower expects to see a 5x-8x return on each pound of seed potato he or she plants. In other words, plant a pound of potatoes, and you're doing well if you get anywhere from 5 to 8 pounds at harvest.

I planted my six buckets with just under a pound of seed potatoes. To be precise, it was 15.6 ounces of seed which had lost some moisture and begun to sprout (as is recommended for planting potatoes). As the plants grew up inside the bucket, I added more dirt to leave about 5"-6"of growth above the soil line until the buckets were entirely full. As bad luck would have it, spring this year was exceptionally wet. We got hit with late blight on our potato plants in early August, and soon after on our tomato plants as well. All was not lost however with the potatoes. As was recommended to me by our Agricultural Extension agent, I cut the potato plants down to the ground and destroyed them, but left the tubers undisturbed in the soil. If we waited at least a few weeks to harvest, he gave us even chances on harvesting a blight-free crop of the tubers. We followed his excellent advice and so far have seen no evidence of the blight on the spuds themselves.

I'm getting to the yields on our six bucket-grown potato plants in just a moment, but I want to emphasize that the need to cut down the potato plants earlier than normal in the season almost certainly means that our yields were smaller than they otherwise would have been. From the 15.6 ounces of seed planted in the six buckets, I harvested 8 pounds, 8.9 ounces of potatoes on Sunday. That's an 8.8x return, placing the potato bucket harvest slightly above the high end of average commercial yields. In other words, the potato bucket plantings did great, in spite of the blight.

One of the two buckets for which I had the individual seed potato weight produced the lowest yield, probably because it was the one bucket in which I found a few rotten potatoes. That bucket received a 2.3 ounce seed potato, and yielded 1 pound, 4.1 ounces (or 8.7x). The other bucket for which I recorded the seed potato weight (2.1 ounces) yielded 1 pound, 13.5 ounces, or an incredible 14x return. The four buckets for which I did not record individual seed potato weights used 11.2 ounces of seed potato between them, and yielded 6 pounds, 8.2 ounces, or a return of 9.3x collectively. Given that we got hit with late blight, I feel that we could expect a slightly better return in a more average year.

Most of these containers were food-grade plastic, 5-gallon buckets. One was a little smaller than the rest, however this did not seem to make much difference to the quantity of potatoes from that bucket. Although I was not exceptionally rigorous about examining this, it seemed to me that all of the tubers were produced along one part of the plant at the lowest level of the bucket, right around where the original seed potato was placed. The mounding may still have helped these plants produce more by providing additional nutrients. But it did not appear to me that additional sets of tubers were produced higher along the stem as the plant grew upwards.

Although the yields I saw with the potato buckets were nowhere near the fabulous yields ascribed to potato towers, I think the concept has other merits worth considering. For one thing I should note that the potatoes we had in buckets were situated right next to the first group of in-ground potatoes to show late blight, and yet they were the last of all our plants to show any evidence of blight. I believe that the better-than-in-ground drainage in the buckets helped the plants, as did the higher elevation of their stems and leaves, which allowed for better air circulation. Blight strikes where there is enough moisture to support the fungal infestation, and these bucket-grown plants were drier than those in the ground. In fact, I had to water these plants quite a bit, whereas rainfall alone took care of the potatoes in the ground once they were established.

Another benefit of growing the potatoes in buckets was the ease of harvest. All that was necessary was to dump each bucket into a wheelbarrow. Inevitably when digging for potatoes in the ground, I spear a few spuds with my pitchfork. That never happened with the potato buckets. Also, there's very little chance that I missed any potatoes from the buckets. Clearly I missed a few potatoes during last year's harvest, because I had a few volunteer potato plants where they weren't especially wanted in the garden this spring. Though the buckets were heavy, the harvest from potato buckets was much easier than the digging we'll need to do to harvest the rest of our potatoes. In terms of yield per square foot of garden space, I honestly cannot say whether the buckets are superior to growing potatoes in the ground. But the harvest was very easy indeed.

I know I've seen a picture, somewhere, of planters stacked in a pyramid shape, with plants growing out of each one. (I've you've seen this picture whilst poking around the intertubes, please point us there in the comments.) Each container on the second course straddles at least two containers on the first level, leaving enough room for the plants in the first course to grow. While I wouldn't want to build a very high pyramid with 5-gallon buckets, I think it might be worth trying. Anything above 3 courses high would be too difficult to fill in gradually, water, or remove for harvesting. But the pyramid idea would help to maximize the yield from a given area of garden space. And it could be grown on a driveway or some other space not otherwise useful for food production.

Rob over at One Straw has been experimenting this year with 2'x2' potato towers. He should be harvesting them fairly soon. I look forward to seeing what we can learn from his results this year.

21 comments:

Chile said...

My husband planted some sprouted potatoes in buckets recently. I hope he gets better results from the mounding part than you did. Instead of just mounding up in one bucket, he cut the bottoms off two more buckets (for each planted bucket) and will extend the height of the bucket tower as the plants grow up.

Wendy said...

That's an awesome yield! I don't think my potato bed did as well. I think I may have gotten 5x to 6x, but I can't remember how much I planted :).

I wasn't as meticulous as you were with recording my yields, but I did find that, even though I, basically, ignored the potatoes I'd planted in the buckets after the first application of compost, I still harvested a few potatoes from each bucket :).

I still haven't harvested the potato tower, yet. I'm planning to wait until after the frost as the plant still looks really good.

The pyramid idea sounds interesting and is definitely something that would be of great use in a small, urban/suburban homestead where small-space techniques are necessary.

el said...

Pretty scientific, Kate. What kind of soil did you use: did you dig up some garden soil, amended with compost, etc.? I know you mentioned that your soil was clay. I ascribe all kinds of magicalness to my plain old garden soil (all those critters living in it you know) so I would be curious to see if you used bagged dirt or just what you had lying around.

Despite the chance of a higher yield, I think I will leave mine in the ground: ground is one thing I have quite a lot of!

Kate said...

Chile, my impression is that higher mounding does not produce additional clusters of spuds, though the spuds at the bottom *might* be more numerous or larger. Good luck with your trial and I hope you will share your results.

Wendy, thanks! I will have an overall sense of how well my in-ground potatoes did when I'm done with the harvest, probably sometime next month. I hope you will share whatever else you learn from your tower experiment.

El, thanks. I'm flattered you think I sound scientific! I used our clay garden soil mixed with the compost from our yard waste facility. Well, actually, it wasn't all really well mixed - sometimes it was only alternate layers of clay and compost. If I did this again I would be more meticulous about mixing the two. The clay layers were sometimes quite wet, even though we haven't had much rain lately, and the top strata were quite dry. The few rotten potatoes we found were in wet clay.

I mixed the soils up very well in the wheelbarrow after I'd gotten the spuds out of each load, then put it all back in each bucket. So now I have six buckets of beautifully mixed soil. I should do something good with it soon!

Billie said...

I only have a balcony so I am thinking I might be able to grow potatoes like this. How do you know that the Kitty litter bucket is food grade? I can easily get some of these but am not sure how to get a plastic food grade bucket otherwise.

TeresaNoelleRoberts said...

I'll have to try German butterballs and lots of compost next year. We did OK with packaged potting soil (which everyone said we HAD to use for container growing) and Katahdins, but your yield was much better.

Walker said...

I have tried both plastic buckets and potato towers (this is my first year growing potatoes). I used self-watering containers (bucket inside bucket with a water space at the bottom and a portal for water to infuse up through the soil from below, keeping a constant, even moisture level) and had good luck, even though I forgot to do the burying trick in the buckets -- I have harvested one and got 4 lbs from one small seed potato (probably 3 oz.) ...

I haven't harvested the towers yet because the potatoes are still growing like crazy -- the plants are still verdant, so I'm taking that as a good sign for high yield.

Walker said...

P.S. What is the best thing to do with the soil after potatoes? Everything I've read says "no nightshade family" -- is there a good rotation crop for the soil in those buckets (an especially good complement to the spuds)?

onestraw said...

Great post Kate! I am about 2 weeks from harvesting mine - still have some top growth so I am letting them go as long as possible - that is another advantage about container spuds - you don't have to rush things to get a cover crop in!

-Rob

Brown Thumb Mama said...

Wow, I'm going to have to try that next year. My potato crop this year was dismal...but it's my first time with taters, so that's my excuse. Now, to round up some buckets!

Kate said...

Billie, I don't. The kitty litter bucket is one of the six that is almost certainly not food-grade plastic. If such things are a big concern for you, I recommend you seek out food-grade plastic containers. You might dry delis or stores that sell olives or pickles in bulk. They may have what you're looking for.

TNR, good luck with next year's crop.

Walker, that sounds like an amazing yield. I have to admit that it was tough to keep the potatoes in buckets watered just right. A self-watering container might just do the trick. Another area for experimentation next year!

I might use the soil for leafy greens before just returning it to the garden. But yeah, I would steer clear of using it for the nightshade family too. Apparently hard frost will kill any blight spores that might be in the soil. But that's still several weeks off where I live.

Rob, thanks. You know I'm on tenterhooks waiting to hear your results. Let us know when you know.

BTM, the first year with any crop hardly counts, in my opinion. I hope you'll have fun with the bucket idea. Good luck with it.

Cheryl (SwineInsanity) said...

We planted potatoes in a new plastic garbage can with holes in the bottom.. Have heard of people using old tires... I also did the Ruth Stout way of growing potatoes above ground... I will say.. the ruth stout way was the easiest but most expesive way if you don't have straw or compost on hand...

Anonymous said...

Bakeries are a good source of food grade buckets. They go though a lot buckets of frosting and filling. Check their dumpsters.

Steven said...

Not sure you're still checking comments on an old post, but I've got my buckets, and I'm gearing up to grow potatoes in them like you did. Do you recommend cutting holes in the bottoms, or cutting the bottoms off completely? Thanks for a great idea!

Kate said...

Cheryl, I love the way Ruth planted her potatoes. I may go that way eventually. But for now I'm experimenting with pushing for high yields.

Anon, great tip about the bakeries and delis as sources of food grade buckets.

Steven, I still get notices on all comments. Sorry it's taken me a while to reply. Been rather busy lately. I just drilled holes for drainage in the bottoms of the buckets. However, I am going to be using a different method this year, turning each bucket into a self-watering container. I'll post about this when it gets close to potato-planting time. Stay tuned if you're curious.

Steve said...

Thanks for your response. I'm trying to replicate your experiment this year. How big of holes and how many did you drill for drainage in the bottoms? I was going to run a soaker hose across the top of the buckets for watering. Also, did you notice any greening of the potatoes due to light penetration of the white buckets? I got 18 free used pickle buckets, and a couple of my Red Thumbs are getting soft, so I'm itching to plant. I'm a little worried that the buckets will be more vulnerable to frost than in ground potatoes. I'd really appreciate any other advice you have.

Kate said...

Steve, I can't remember exactly. Probably 1/4" holes or thereabouts. Probably 6-8 holes altogether. Nothing fancy, that's for sure. If you want, check out my recent-ish post on figs in containers. It shows the type of self-watering container I'm going to use for some of my potatoes this year. I'm just adapting the technique used for the figs to the 5-gallon buckets.

Steve said...

Thanks! Did you plant your potatoes outside prior to the last frost, or after? I'm wondering if the soil in the buckets don't retain heat overnight as well as regular planting, and might get frost bitten. BTW, I'm looking forward to your potato self-watering post. I'll be interested in your refinements to the fig method. I really, really appreciate your blog. It's been incredibly helpful.

Kate said...

Steve, I usually plant potatoes in April, well before our risk of frost is over. I'm slightly behind schedule this year, but I think we'll plant by this weekend. I don't think a little frost will hurt potatoes. The bigger risk is cold damp soil. I usually dig the potato trenches a day or two before a really sunny day, then plant on the afternoon of that sunny day. That way the soil is warm and dry when the potatoes go into the trench. Especially important if you plan to cut the seed potatoes in pieces for planting. I don't think temperature is as much of an issue in the buckets, unless you expect to see several days of sub-freezing temperature. Just put the buckets where they'll get good sun during the day, and make sure there's at least six inches of soil in the buckets to hold the heat. The overnight temps shouldn't harm the seeds.

Terri W said...

Hi Kate, I have never tried it myself but I have read accounts and have seen pics of people who are doing this in 55 gallon plastic barrels with great results. Maybe it is the increased space but I believe they are getting new tubers and potatoes all the way to the top of the barrels. Just something to consider. Caught my eye because I have a lot of these barrels around & thought I'd like to try it. Fortunate for us though we live in PA potato country with a lot of local potato farms so it is easier to just bargain with them. Leaves me more space for everything else...LOL LOVE your blog by the way!!!!

Kate said...

Terri, hi and welcome. I live in what used to be PA potato country, but no longer. Now I wonder where PA potato country is, exactly. I've heard those stories about potatoes all along a tall potato stem too, but have never been able to track down details or documentation. And the trials I have read about where people try deep mulching the potatoes have not succeeded in increasing the tuber set. If you have a link or reference to someone who has done this I would love to see it.