Simple advice on potatoes please

[jimmacfarlane]

Hi,

2nd year of growing veg in raised beds and loving it! Could I have a bit of very simple advice? I'm trying to grow potatoes in big pots on a patio. I bought seed potatoes late from Homebase a couple of weeks ago and they had already sprouted, the longest of which were about 10 inches long! I read that they can still do fine if you plant them like this. I carefully did this a couple of weeks ago without breaking the shoots so that the tips of the shoots were just under the surface of the soil. They are now breaking through with small green leaves. It is this stage that I don't fully understand. Do I continue to pile earth on top of the developing leaves to encourage stronger growth or do I wait until they are above soil level and pile the soil up beneath the leaves to cover the shoots/stems themselves?

Thanks and sorry this is a rather basic query for most.

Jim

[JosephsGarden]

Potato tubers which form about the same time the plants are flowering will often times poke out of the ground... If they get exposed to sunlight they will turn green, and the tubers will develop a poison that tastes nasty bitter: Thus ruining that tuber. The purpose of hilling potatoes is to keep the tubers in the dark so that they don't become poisonous.

If you cover green leaves you are preventing the plant from obtaining sunlight and can expect lower yields. So when hilling it is advantageous to leave as much leaf exposed as possible and target covering the stems. Some varieties of potatoes will grow additional tubers along the buried stems... There is only so much sunlight available to be turned into tubers, so while there might be more total tubers the average size tends to be smaller.

[evtubbergh]

I agree with JosephsGarden. I did that and my plant died. Leave it but leave a little space at the top for hilling later on to cover up developing tubers. I would only go with 2 inches or so. Rather give your plant more space for root development.

I did the research for our experiment (which we will have to try again this year) and you actually need quite a lot of space for one plant; about 2 feet diameter and 2 feet deep. We built a box almost that size but unfortunately our plant didn't get big enough to even mildy use the space so can't help you there.

I was given advice about people hilling and using boxes for that almost like it's fashion but it not being necessary. https://www.helpfulgardener.com/forum/vi ... 79&t=55441

[grrlgeek]

They are now breaking through with small green leaves. It is this stage that I don't fully understand. Do I continue to pile earth on top of the developing leaves to encourage stronger growth or do I wait until they are above soil level and pile the soil up beneath the leaves to cover the shoots/stems themselves?

At this point, you need to wait until the plant has grown to about 8-10" tall. At that point, hill by adding soil to the container until only about 4" of the plant remains above the surface. Repeat this cycle until you run out of room in the container.

Potatoes are so fun to grow! Enjoy!

[jimmacfarlane]

Right I've got it! Thanks to all for the excellent advice. Amazing to have replies from the other side of the world!

[jal_ut]

At this point just let them grow. As Joseph mentioned the tubers form about the time the plant blooms. It is at this time you need to hill. Just add a bit of soil around the plant such that it gives the growing tubers better cover so they don't see daylight. The hilling is only for that purpose. You don't want to cover leaves, and don't need to cover stems, but will likely cover a bit of the stems in the hilling.

I grow potatoes in rows spaced 30 inches. When hilling time comes, I pull some soil from the space between plants in toward the plants to hill them. This leaves a sort of trench in the center of the rows.

[lexusnexus]

Jim, please put your location and hardiness zone in your profile so advice is appropriate for your area. Otherwise we have to guess.

[rainbowgardener]

Sorry, James (jal_ut) is a very experienced and successful gardener/farmer and he grows tons of potatoes and I do not. But his advice is about growing potatoes in fields NOT about growing potatoes in pots.

Potatoes grow off of underground stems, between the real roots and the ground surface:


https://assoc.garden.org/courseweb/cours ... wk4-c1.gif



https://ibguides.com/images/9.1.4_potato_tuber.png

the second one doesn't show the ground level line, but all those tubers have to be underground.

So if you are growing in a field and there is plenty of room to spread out horizontally, then they don't need to be very deep. If you are growing in a pot, there's not room for them to spread horizontally, so you have to encourage a long length of underground vertical stem for the tuber stems to come off of. You do that by repeatedly burying the stem. But you do have to wait and let it grow for awhile and always leave it plenty of unburied leaves, because it is the leaves that feed the plant.

I do grow potatoes in pots and I will say with the lack of space and keeping on burying a lot of the leaves and whatever other factors, it is very difficult to get full sized potatoes. Mine tend to come out about golf ball sized.

[jimmacfarlane]

Thanks all for the advice, I understand now. Leaves and stem coming up nicely now and will know when to start hilling. Profile updated - am from Newcastle upon Tyne, North East England. Not quite sure what zone it would be - but generally coastal, up to 25-30oC during the summer and down to -5oC in winter.

Thanks Jim

[feldon30]

Thanks all for the advice, I understand now. Leaves and stem coming up nicely now and will know when to start hilling. Profile updated - am from Newcastle upon Tyne, North East England. Not quite sure what zone it would be - but generally coastal, up to 25-30oC during the summer and down to -5oC in winter.

Thanks Jim

Looks like you are a Zone 8 equivalent:
https://en.wikipedia.org/wiki/Hardiness_ ... nd_Ireland

[jal_ut]

rainbowgardener, how large of pots are you using? I would think at least a six gallon pot for a potato plant?

Try adding soil only one time when the plant blooms and not covering leaves. See if you get larger tubers.

[tomc]

Maps for USDA hardiness zones exist world-wide. Any search engine will promptly show links. What those maps don't do is identify cities and towns. That will be your human part of this search.

An outline map of all of Scotland, Ireland, England, and Wales came up on at least the top two I looked in on.

Based on an outline map all of the UK are zones 7-8-9.

All of this said, I'm going to hazard a guess that precipitation, and not cold are the pinch-point for growing any nightshade in the UK.

[rainbowgardener]

james: I have one that is a tree sized pot, maybe 10 -15 gallons and 2 that are old trash cans (like you take out to the street) cut down, so more like at least 20 gallons. I will at least slow down and let it grow more before adding soil....

[Ohio Tiller]

If you are growing in pots make sure you have a real nice loose soil I use to add sand to mine so they can grow and get nice and big instead of small and dense potatoes. I don't grow in pots any longer now that I have room in the garden.