Growing potatoes under black plastic
 

Last year I tried growing some potatoes under black plastic and since the trial was so successful I planted more that way this spring. In mid May I spread two pieces of 1 meter wide and 20 meters long plastic sheet on top of the tilled soil. I made two rows of slits in both plastic sheets and planted a potato in each slit.

This is how the potato plants looked in June.

Today was time to start harvesting them since most of the stems had started to die. It had rained couple of nights, but the soil was still quite dry and easy to dig. I was amazed about the size and amount of the tubers which had grown without watering them during them during the dry summer.

Sari

The first photo shows how close the tubers were planted to each other and how the potatoes were when the plastic was removed. This variety is King Edward, which I had only few seed potaoes.

Second photo shows harvest from four Mayan Gold seed tubers. Each of them had made about 12 potatoes. These had still quite much green on the leaves, but since the potatoes were already quite large, I ended up lifting also rest of them.

I have still three varieties growing under plack plastic and all the ones planted the traditional way in rows by the tractor pulled potato planter are still growing.

Sari

You got a nice harvest. I am surprised that they would grow in such dry conditions.

Very impressive yields. Sounds like a successful and low maintainence experiment.

Nice work. I am a fan of black plastic mulch, too.

Wow - that's terrific, svalli. I'm curious, though, as to how deep you originally planted them? Also, did you add anything else at planting time?

Before planting I rototilled the soil and added granular fertilizer. The seed potatoes were just pushed beneath the soil through the slits, so they were not really deep.

I noticed that some varieties had grown many potatoes away from the stem and potatoes were either below the soil or just under the plastic and no green potatoes. The ones which have Solanum phureja crossed in them had the tubers close to the stem, so the potatoes on the top had got green in them. Those varieties may need some organic mulch or a bit of soil put on top of the opening in the plastic.

This was definitely so easy way to grow potatoes that we may skip doing it the traditional way. This takes more manual work during planting, but yield is much better. I can easily grow what we eat in three 1m x 20m beds. Once again we had to empty the root cellar from sprouted potatoes, which we grew for my father-in-law last year, so he may also now admit that there will be no famine even the cellar does not burst from potatoes at fall.

Sari

Thanks for sharing this method. It seems almost inconceivable to me that potatoes can be grown without trenching/hilling them! Once or twice I planted potatoes and then failed to get them trenched when the time came, and yields were really poor. But perhaps that is because the trenching we do is a way of suppressing the weeds too. (We turn the weeds over with the spade so they also serve as a green manure, and usually put fish around the plants under the trenching.)


This method might work well at my friend's farm, where the soil is really rich (and of course applying some ferts at planting time as you do).



Is there anything you can tell me about the right plastic mulch? Is it durable enough to use for several seasons, or is one type better/more durable than another? I would like to look into the cost for that. Thanks!8-)

Very nice thanks for sharing.
I would eat the variety with green tops first, i think the drying of tops toughens the skin for storage.

The plastic, which I use is similar to the one used in the thick large trash bags. The one sold here is UV-protected and is sold for planting strawberries. I have used same plastic for many years for garlic and onions and with care at harvest time it can last multiple seasons.

I think that the potatoes do not really have to be grown in hills, if the soil is good and there is some kind of mulch to prevent weeds and sunburn on the growing tubers. We have grown potatoes many years, but it seems that there is still lot to learn about the methods and how the weather affects the size and quality of the harvest.

Usually we throw the green potatoes away at harvest time, but since the Phureja crosses are hard to find, I'm planning to save all green ones as seed potatoes.

Sari

I do not grow mine in hills. I plant the seed potatoes shallowly in the soil and then cover with a deep layer of straw. I guess that I actually hill up the straw. You need to keep light excluded from the developing tubers.

This works well for a home gardener but wouldn't work so well in a farm application because you would need LOTS of straw.

[url=https://flic.kr/p/Wgd6EA][img]https://farm5.staticflickr.com/4337/35615373314_90d5392177.jpg[/img][/url][url=https://flic.kr/p/Wgd6EA]DSC00880[/url] by [url=https://www.flickr.com/photos/156361419@N03/]Brownrexx[/url], on Flickr

Here is what the potatoes look like when I pull the straw back using just my hands. The 2 red ones must have come from a volunteer plant because my potatoes were planted in the same location as last year when I grew red ones. .

[url=https://flic.kr/p/27hdWHW][img]https://farm2.staticflickr.com/1814/42190422520_10fb5758aa.jpg[/img][/url][url=https://flic.kr/p/27hdWHW]20180812_122732[/url] by [url=https://www.flickr.com/photos/156361419@N03/]Brownrexx[/url], on Flickr

That's also a cool method, Brownrexx. :)
Tx for info about the mulch Svalli. I spent a few hours looking at different types last night - I'm amazed there are woven plastic fabrics that are rated to last up to 25 years. :surprised: It would be so worth it, although you do have to burn the holes or else they unravel.:?!?: I think this is what PH and PMcG are using for garlic.

I had some woven blue plastic tarps when I was first cutting wood here.. my goodness they didn't last more than a couple of years, and I literally spent.. days I guess if not weeks of my time trying to pick up the million little blue fibers that scattered everywhere. :shock::( Something that lasts long is the best choice, but I will need some reassurance it can survive our freeze and thaw winters.



One thing mentioned about the woven stuff is that it allows air and water through. But you had success with a solid piece as well, and no drip irrigation - that's good to know.


Garlic and potatoes are two crops that rarely ever get watered even once during the season here.

Things got too hot here and way too fast too, so I am surprised you got such a great harvest with watering! It's always nice to read about success, and may try some of your tips. I use a landscape fabric rated for 25 years for mulch, so may use that for potatoes, too, but it's a have to be in the front thing due to the pecan trees.

Maybe things are different here in PA but I get smaller potatoes when the plants get less water and I have read that they need water especially after they flower because that is when the tubers really get growing. I grow mainly Kennebec so maybe variety plays a role too.

I also get bigger potatoes when I plant the seed potatoes farther apart. I like the baking sized potatoes so I plant almost a foot apart. When I plant them closer I get lots of small round ones and a few big ones.

I dug up one more variety yesterday. The leaves had a bit green on them, but the potatoes were already so large, that they do not need to grow anymore. Week ago I dug up couple varieties from he field, where we have no mulch and the potatoes were much smaller than the ones grown with plastic mulch.
The plastic mulch definitely helps retaining moisture and made a big difference in a dry summer like we had. I do not look forward to wet summers, but it will be a good test to see how this method works in our typical rainy summer.

Picture below shows what I got from 29 seed potatoes of Mozart. When all were picked up we got two full 45 liter vegetable crates. Biggest spud weighed almost 700 g (1½ lb) and there are quite many which are over a pound. This variety is excellent yellow flesh baking potato. Mozart on the field was planted couple of weeks later than these and are still growing, so it will interesting to compare the size of those to these. Now we are getting the typical autumn rains and hopefully the potatoes will keep growing until the first frost.

Sari

That spud is huge! :D Your father-in-law should be impressed with that one, enough to feed a family! :)8-)

Works very well with strawberry plants also, so much so that commercial operations use it on a very large scale

Wonderful, Svalli! How hot does it get in the summer where you are? I might have to try just three or four potatoes under plastic next year and plant next to the traditionally planted and hilled ones.

OH MY! that is awesome. I don't know how I missed this last year, but I did. this is fantastic to see. I don't grow potatoes as they are are too much work and yield too little for the space I am giving up but this makes it looks too easy. and I do have a spot I can try this method on and fingerlings left over from last year to do it with. I bought them at a farmers market and "lost" them and when I finally found them (hanging behind the door in the pantry... it was too late to eat them as they had sprouts all over them....

[QUOTE=GoDawgs;732965]Wonderful, Svalli! How hot does it get in the summer where you are? I might have to try just three or four potatoes under plastic next year and plant next to the traditionally planted and hilled ones.[/QUOTE]

We do not get really hot weather even last summer was record hot. Average higs are usually in the lower 80's in Fahrenheit. Using black plastic seemed to help a lot to warm the soil early and keep moisture in the ground.
I am planning to use this method again this year.

My plastic covered potato patch was planted last week. Since it was so successful last year, this time I added one 20 meter row. Hubby still wants to plant some Yukon Golds with the tractor pulled planter on another field, but I try to convince him that we do it manually with plastic mulch. Planting manually to the holes in the plastic is more work, but no weeding is needed.

Beautiful Farmland

[QUOTE=svalli;713252]The plastic, which I use is similar to the one used in the thick large trash bags. The one sold here is UV-protected and is sold for planting strawberries. I have used same plastic for many years for garlic and onions and with care at harvest time it can last multiple seasons.

I think that the potatoes do not really have to be grown in hills, if the soil is good and there is some kind of mulch to prevent weeds and sunburn on the growing tubers. We have grown potatoes many years, but it seems that there is still lot to learn about the methods and how the weather affects the size and quality of the harvest.

Usually we throw the green potatoes away at harvest time, but since the Phureja crosses are hard to find, I'm planning to save all green ones as seed potatoes.

Sari[/QUOTE]

What low temps did you have when you planted them & throughout the season? I thought I read (or Tom told me) nights needed to be below 60F or something like that... I forgot the degree needed to form fruits...

[QUOTE=korney19;743868]What low temps did you have when you planted them & throughout the season? I thought I read (or Tom told me) nights needed to be below 60F or something like that... I forgot the degree needed to form fruits...[/QUOTE]

Lows here when planting potatoes, can go below freezing, but hopefully not anymore after there is top growth. This year we had a frost even in July, which killed top leaves of some of my potato plants in the field, which is in a open area. Luckily my first planted patch was not affected.

If the lows have to be below 60°F, this area is the good for growing potatoes, since the average low does not get above that. Last summer there were some warmer nights, but also the colder ones too.

Sari

Last week was rainy, but Saturday sun was shining, so I went to harvest potatoes. One advantage of the plastic is that the soil underneath does not get soggy, even it has been raining. Potatoes in this patch had grown well despite the summer was dry and I did not water them at all. I did not get such monster size spuds like year ago, but still there were quite large ones.

We have still three similar rows in an other field. Those were planted later and are a bit behind in growth, so I am hoping that the killing frost does not come in end of this week like predicted. Anyway we got enough potatoes harvested already, so it is not a problem, if the later ones, do not produce so well.

Sari

Wow! What a super harvest! Why mess with success? :lol:

I think I'm going to try a couple of hills of fall planted potatoes and hopefully remember to try your black plastic trick on them.

Excellent harvest! 8-)

Svalli, you inspired me. I canceled currants and raspberries on a bed 2 x 8 meters. I will plant early potatoes there in the early spring. After the harvest in September, I will sow the lawn there. I have been using woven black foil repeatedly more than for five years. I grow in them everything from strawberries through tomatoes to salads.
Vladimír

S, what potato varieties are you planing this year for 2020?