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The pot-in-pot method of growing uses a production pot inside another pot which is in ground. This allows you to swap pots easily, and some 20 good reasons why this might be a good idea are listed here.

One other reason I came across was that if you had one production pot sitting on say 4 inches of soil in the ground pot, the latter would reduce perching of water in the production pot improving the aeration of the roots.

I can see this being useful for me as plants wouldn't get blown over in the wind, and watering would be easier if I had frost tender plants in the garden with the rest of the plants. And then I can pull them out for over wintering inside the house, and replace with a winter plant.

So, are there any particular characteristics of the pots that are needed for this to work? Obviously both pots need to drain, be light weight, durable, and you need a light growing medium. Anything else?

tree nursery using pot-in-pot method

  • The pots need good drainage as well so that you don't drown the roots with water collecting inside the host pot. So, the ground may need to be sloped, or drains built underneath the in ground pot. – Graham Chiu Mar 30 '16 at 18:59
  • So this is actually a new question rather than a refinement of an existing question. I think it's should have been asked separately. – Escoce Apr 2 '16 at 2:05
  • @Escoce not sure what you're referring to. I just added benefits to this method. – Graham Chiu Apr 2 '16 at 2:56
  • I am sorry, I retract my statement. I could have sworn the question title itself said something else, but edits clearly show its unchanged, so my apology. – Escoce Apr 2 '16 at 3:00
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This technique is used by commercial growers for tree and shrub production

  • the pots you use should be identical and readily available in bulk quantities
  • sandy soil is probably not the best if you are growing trees as it will shift in high winds
  • ready access to water. Plant material using this method can dry out faster and a drip or bubbler irrigation system is commonly used in the summer
  • +1, and one of its main purposes is to keep the rootball warm in the winter and cool during the summer depending on your location. Regarding sand, sandy soil, and soily sand, I wouldn't worry too much about sand shifting. Even in heavily sandy regions, the soil does setup unless you are really in the deep desert like the Sahara. When I lived in Sarasota Florida where we had what is classified as soily sand (mostly sand with only a touch of ash and organic matter), the ground moisture and organic matter held the sand together. I have even dug down 3 - 4 ft vertically without collapse. – Escoce Mar 30 '16 at 14:20
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    The overwhelming reason for pot-in-pot is to lower root temperatures in commercial nurseries. Black pots adsorb a lot of solar energy (i.e., they look black because that adsorb light rather than reflect it). Near the pot wall the soil temperature of a pot sitting out in the sun can easily exceed 95F, the temperature at which root growth has stopped and 115F where roots die. – Jim Young Mar 30 '16 at 16:41
  • @JimYoung excellent point. You should provide it as an answer or edit into one the existing answers – kevinsky Mar 30 '16 at 16:43
  • The in-ground pot is called the socket, and the one containing the plant is called the liner. There should be an air gap between them when the liner sits in the socket to minimize growth of roots from the liner into the socket. Root through growth makes it very difficult to remove the plant. – Graham Chiu Dec 18 '16 at 23:35
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The overwhelming reason for pot-in-pot is to lower root temperatures in commercial nurseries. Black pots adsorb a lot of solar energy (i.e., they look black because that adsorb light rather than reflect it). Near the pot wall the soil temperature of a pot sitting out in the sun can easily exceed 95F, the temperature at which root growth has stopped and 115F where roots die.

  • And the reason nursery pots are black, is because it protects the pot from UV brittling. – Escoce Mar 31 '16 at 14:16
  • Get pots with a very sturdy edge for use to plant directly in. That way heaving them out again may be easier than with a flimsy flexible rim. – user13638 Apr 2 '16 at 10:39

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