Kenosha Potato Project

How to grow potato in a bag

This page is linked to the Kenosha Potato Project web pages. See these links for


Growing potato in a bag - planting tips. [see in red corrections made in 2011]
To order bags from Gardener's Supply - please click here

Potato Growing Bags can be used on a deck, concrete ... without digging ... but it will be very difficult to control the best moisture level for the potato vines! Water too much and the tubers will rot, water too little and the yield will be smaller.

We recommend to sink the bag 4" in the soil

  • first fold the bag back 4"
  • cut an 18" circle with a spade
  • remove 4" of top soil and place the bag in the hole
  • fill the bottom 2" of the bag with rich compost (we are testing a sand - compost mix to see how the root system development changes) - about 4 large shovel loads.
  • place the seed (one in the center - 5 in a star shape) - we recommend to use small whole tubers - walnut to small peach size - because cut pieces rot faster, while large tubers may not rot at all ... but are no longer edible, and may be difficult to recognize when you harvest.


sink bag in the soil 4" place 6 small whole tubers in the bag
  • Notice in the picture one seed piece is placed in the center - the main objective of this growing method is to learn how high up the vines of different varieties set tubers! The vines that grow around the center will help you to retain more dirt in the center - the center vine will have the deepest growth area.
  • we recommend to only use one potato variety per bag - different varieties likely have different growing habits ... too difficult to manage!
  • cover the seed pieces with 6 - 8" of growing matter (we are testing mixes of compost, dirt, sand, mulch, leaves) ... and will report on the results.
  • make sure you stay on top of the filling task as the vines grow!!! Don't let the vines stay exposed to light for too many days. Light hardens the vines, and you will get no tubers from that point up!
  • once the vines reach the top of the folded bag, unfold the top 4" and keep adding growing matter as the vines grow - don't leave the vines exposed to the light for more than 5 days!
  • sink your hand in the bag to "steal" tubers ... depending on the variety ... you may be able to find tubers after 50 to 100 days
  • you can wait to empty out the bag after the vines have completely died back.
  • weigh the tubers and report back to us ... you can credit on these web pages if you can provide these details:
    • cultivar / variety name
    • source of the seed
    • confirmation that you have started with 6 tuber pieces
  • weight in pounds or kilograms of total yield (including early steals)

Please test with 6 seed pieces per bag. You may test with fewer seed pieces per bag. Please remember to report how many seed pieces per bag.

Please return to this web page at the end of the next growing season (2011) to compare yields. We have more than 100 bags being used with almost as many different varieties (very few modern cultivars, most are heritage varieties). Scroll down to read about the current disappointing results. But we love the bags and will keep using them. Our main benefit is growing more varieties in limited space.


More benefits of growing tubers in bags

As my personal collection of potato varieties keeps growing in size, I'm concerned with how much space is needed. Here are more benefits for the potato collector:

  • One variety per bag, no need to space between varieties to keep different varieties separated.
  • More seed pieces per bag (six) - as seed crowding should yield smaller tubers, which is the best size for next year's planting.
  • In this picture you count 20 bags placed on a plot of 3 x 18 feet - in the same area I usually plant 9 varieties in a traditional furrow (27 seed pieces), while these bags contain 6 x 20 = 120 seed pieces, or almost 4.5 times more.
Notice: 2010 Spring bags are not filled enough!

Go to the bottom of this page to understand why bags need to filled with 6 - 8" of growing matter.

With bags expected to yield more tubers that should develop in the higher soil level. The traditional furrow allows for about 6 - 10" of soil depth for tuber development, while in the bag the tubers may develop in up to 16" of soil (measurements taken by allowing 2" of soil under the seed piece, 14" of bag heigth, plus up to 4" of soil hilling on top and in the center of the bag.

Farmers measure potato yields in hundred of pounds per acre - which makes it quite complicated to compare garden yields to field yields. These web pages are developed for the pleasure of gardeners. Please return to see the comparisons of crop yields grown in traditional furrows vs. the potato bag / the potato box.


Planted in May - some varieties already reaching the top to the bag by mid June.

Notice how different varieties will show different growing habits. Some grow faster, some grow taller.

We recommend to plant only one variety per bag.

Yields results in 2010 ... quite poor!

The bag manufacturer suggests that you can harvest 7 pounds from one bag!

At the time of this web page update (October 2010) I don't have yields reports from other members of the Kenosha Potato Project, except for one reporting a wopping 11 pounds.

My results with over 70 bags are quite poor for three reasons

  • My growing method without watering - WATERING IS A MUST TO OBTAIN LARGER YIELDS!
  • 2010 was exceptionally warm and dry - vines don't grow large tubers in temps above 90 degrees ... and black bags above ground can get quite warm.
  • In the Spring of 2010 I did not fill the bags with enough growing matter - only 2" instead of 6 - 8" that is now recommended - read on to next paragraph (seed depth) to understand why!

I'm reporting about two thirds of my 70 bags (45 bags) with a small yield between half a pound to two pounds; 20 bags in the 2 - 3 pound range and only 5 bags with 3 -5 pound range.

The best results were obtained with bags in part-shade and tuber varieties with short stolons. Perhaps because of the soil temperature in the bags above soil level, I found no higher tuber setting!

The varieties grown in boxes have done better, although we are far from 99 pounds yields, we did find tubers as high as 30" above the soil line.


Seed depth affects yields?

A 1942 - 45 three years USDA study of how seed piece depth affects yields clearly shows that yields may be cut by as much as 30% with seed pieces planted at 2" below soil surface vs. 6" below surface.

In 2010 I thought to only layer the seed pieces with 2" of growing matter to accelerate vine emergence. After reading the above mentioned study I now understand that the lower yields obtained with seed pieces placed at 2" depth are also caused by delayed vine emergence. Seed pieces need to be covered with 6 - 8" of growing matter to prevent dehydration which would cause a delayed vine emergence and lower yields. So, in 2011 at planting time, the bags will immediately be filled up to the 4" fold back.


2011 Season Results

Click on these links to review the results for 148 varieties


If you want to participate .... please email us!
We accept reports on yields and will include your observations ... but to keep things simple, we only report for comparison the yields harvested from bags as shown above or boxes, as seen in the link below.

Click here to see the box page>


Wanted: Potato Gardeners

If you'd like to participate with the Kenosha Potato Project - here are your options:

  • If you live in Southeastern Wisconsin - please email me at
  • If you live somewhere else in the USA or Canada - are you a member of Seed Saver Exchange? We have a few gardener who participate with the Kenosha Potato Project within the Seed Saver Exchange.
  • We have members of our Global Potato Network in Europe and are always please to cooperate with any gardener / farmer. Sending seed abroad is restricted or difficult ... but we may find ways to cooperate.
  • Also, please visit our "Vertical Growth - 99 lbs in micro plot Challenge web pages"

Please join us on Facebook - click here


web page updated: March 2011
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