JeanM
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leggy potatoes plants were started too early in the house

I started my seed potatoes using Espoma potting soil and they have grown very large(picture attached) I am planting them outside in large containers but the weather is still not warm enough here in NJ. Some of the plants are over 12 inches. SInce I am planting them in containers and will need to hill them can I cut off some of the top parts of the stem without damaging the potatoe plant. If so, how much of the stem should I cut. WIll that prevent the plant from flowering? must the plant flower to produce the tubers. The root system is well developed. This is my first time with potatoes and I appreciate your help. THanks.
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applestar
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Location: Zone 6, NJ (3/M)4/E ~ 10/M(11/B)

Where in NJ are you? I already planted mine in the beginning of April. I found some overgrown grocery store potatoes as well as my own saved seed potatoes in the back of the pantry :roll:

Subject: Potato too far along to plant?
applestar wrote:That purple-stemmed one looks NICE! That's the Russian Blue? 8)

I guess you didn't see my post about these :>
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I planted them in the first week or so of April, which was a week later than my usual time to plant potatoes about a month before last average frost. Details are here:
Subject: Applestar's 2016 Garden

They have been sprouting out of the ground and looking pretty healthy. You'll find updates and current photos later in the thread.
You will need very large containers -- I assume you know that? 15 gallons or larger, especially with multiple plants like this. I'm thinking 1-2 plants (1 seed potato piece with 1-2 eyes) per 5 gallon. 1/2 barrel planters will work, or those fabric pots that are popular now -- you can get them in 25 gallon and even larger. They even sell some of those branded as potato pots.

What I suggest you do is lay those started potato plants in the pots on their sides or plop up at 15-30° angle for a few days before planting -- this is a trick I use for planting tomatoes deep. The top of the plants will will respond to gravity upwards so that they are now making a sharp turn to the side at the top. Bury all but the top 4 inches or so.

-- oh, to answer your questions -- new tubers grow on the stems ABOVE the seed potato. So more stem you have buried (So the growing tubers don't see the sun) more chance of tubers developing ( this will depend on fertility of the soil and watering which you will need to monitor closely in containers). You will ALSO want at least 6-8 inches of soil under the seed potato in the container.

Only some potato varieties with wild genetics will bloom -- many cultivated potato varieties have ceased to make flowers (Wildly colored ones tend to bloom more). Flowers are not necessary for tuber formation but can be used for judging maturity of the plants -- tiny new tubers begin to develop by the time they bloom.

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applestar
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It's not too late to plant, though. Hope I didn't give that impression. :wink:

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KitchenGardener
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Its so funny, but I will never look at a sprouting potato the same way again! :()

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jal_ut
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Hmmmm....... I have never planted a potato in a pot. Always plant them out directly in the garden where they will grow. It is common practice to plant them about 2 weeks before the last average frost date.

With those you have , I would just pot them up, or if you have a plot plant them out, and give them some sunshine and see what happens. Since you are still expecting frost You may have to cover them on cold nights?

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jal_ut
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You might also plant a few more directly out in the garden?

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JeanM
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THanks for all of the replies. I have to use the large containers for outside because my soil is like clay and because of all the trees it contains a lot of roots. My main concern was how to plant them in the containers because they are so tall and once I put down the 4 inches on soil under them it would leave not too much more depth for hilling. the containers are 16" deep and 18" wide. So once I put them in, I am left with 12" of room for hilling. Given the length of them now, I could only hill one time and leave about 4 inches of growth unhilled and all the new growth would just be unhilled. Hopefully, enough of the stem would be buried to allow the tubers to grow.

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jal_ut
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The tubers grow on the roots. Not the stems. As the tubers swell up sometimes they break the surface of the soil and the sun hits them. This turns them green and gives them a bad flavor. It is to avoid the tubers seeing daylight that we hill them. It only takes a couple of inches of soil.

JeanM
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jal_ut . As you can see, I need a lot of help. LOL. I actually saw the potatoes growing off the roots. Don't know why I got so confused.

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applestar
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-- Just plant them on their sides like I described above.

This accomplishes two things, one and most important is that you won't have to worry about the current spindly growth which will be hard to protect from flopping over and which will NOT be able to support the later thicker/sturdier growth.

The buried stem will grow roots like tomato stems and the additional roots will support the upper growth. As far as I know, these will also bear the tubers.

Another is that especially if you are worried about frost, etc. buried stem will be protected, and smaller amount protruding above soil level can easily be protected with milk jug etc. cloche.

I will take photos of mine tomorrow and post in my garden thread -- didn't have the energy today. Having settled in for the last three weeks or so, the sprouted growths look no different from normal seed potatoes' growths.

HIlling with nutrient rich soil for a few inches is important, but you can also protect the developing potatoes/tubers from the sun with thick mulch, which you can pile above the rim of the container by putting up a little "fence" -- wire, lawn edging, etc. you just need something to keep the mulch from blowing away or spilling/falling down.

JeanM
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Applestar: I followed your advice and put two plants on their side. THe tops of the stems are turning upward. Because the plants have been in the small container so long, the roots are very tight and When I checked the roots the appeared to be root bound, very tight. Is there any way for me to loosen up the roots and still plants these potatoes.

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applestar
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I'm going to say, don't try but first, just leave them out of the pots on their sides as before, and loosely cover with something -- slightly moistened fluffy potting mix, paper towels, or newspaper and a plastic bag so they don't dry out -- kind of like letting bread dough rise -- this may allow them to loosen up a bit on their own. Then after a couple of hours or overnight, just plant them and loosely cover them -- fluffy and not packing down the potting mix, maybe just water in a bit to allow some to get between the roots. Hopefully they will expand out.

Keep adding potting mix as the mix settles so no roots are exposed and dry out, but keep the mix on the loose and fluffy side.

JeanM
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Applestar: Thank you, I will try this. This NJ weather is causing me all these problems. LOL. TIme to move.

JeanM
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Found this great picture of a potatoe plant which really clarifies its parts and where the tubers come from.

https://www.123rf.com/photo_32570868_sto ... ls-fo.html

https://www.ces.ncsu.edu/wp-content/upl ... oRoots.png

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jal_ut
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If you plant a whole potato each eye will send up a plant. Each plant will make tubers, but they are apt to be small because of the crowding.

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If you cut your planting potatoes to one or two eyes per piece you will get much larger potatoes.

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Good luck on the sprouts.

Taiji
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I think it might depend on how big the seed potato is to begin with. Last year I bought a little net bag of seed potatoes and none of them were bigger than a golf ball. I planted the whole potato and this is some of the harvest I got.
red norlands.JPG

Maybe next year I'll try an experiment: cut the golf ball sized seed potato in half making sure each piece has an eye and see what happens. Maybe I will get twice as many large potatoes, I don't know.



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