Kathy---
I am NOT an expert on AV's---they never bloom for me! I am sure is the light they need--and i don't have...
I think a Greek Yogurt cup would be just fine. Use a hot nail to make drainage holes!!!
It is not too big in diam.--and is shallow--as AV's have shallow roots.
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Here is a great way to transplant fragile plants. or--any other plants.
1--Lift the AV from it's current pot and set it aside on a paper towel as is.
2--Get the new container you plan to put it in. Using the old container as a "space saver"--
put it in the new container and nestle it into the new potting mix--firming gently around the rims.
What you are doing is making a "mold" of the old pot in the new pot filled with fresh Mix.
Make sure the soil level stays the same!
3--Now--gently lift the "old AV" (the one you put aside) and place it in the hollow you made with the
old container. Put the AV into it and--VOILA!! A perfect fit! How about that???
4--If needed--firm gently with fingertips-just try not to press around the leaves too much. They are so fragile!
This technique works so well....transplanting any plant--any size--any pot. Just use a lot of TLC....
BTW--This is a great re-potting technique with any size plants or pots. Even large houseplants!
Main thing is--when you are firming the new soil around the inserted old pot--firm it just right--
BUT--keep it level with the rim of the 'old pot"...DO NOT add extra soil above the level it was growing at.
This can lead to slow death of your plant.
Hope your AV's thrive and bloom their heads off.! Gita