Artificial plants offer the look and feel of the real thing without the hassles associated with maintenance and upkeep--watering is unnecessary and it's impossible to kill an artificial plant. Purchasing unpotted or unshaped artificial plants can result in significant cost savings, but unpotted plants require some upfront work.
Select a cheap, plastic nursery pot large enough to hold the artificial plant. Cover any holes in the nursery pot with packing tape. Place the tape over the hole on the inside of the container rather than the outside to reduce the likelihood of the tape breaking free when spray foam is added later.
Fill the nursery pot halfway with a heavy "anchor" material such as rocks, stones or broken-up bricks.
Arrange the plant as desired in the nursery pot, driving the stem into the anchor material. Hold the plant just above the rim of the container and fill the nursery pot with expanding spray foam, which can be purchased at most craft stores. Allow the foam to set before letting go of the plant. Smooth the top of the foam with a razor or sharp-edged knife, if desired.
Place the plastic nursery pot into the decorative pot. Choose a decorative pot larger than the plastic nursery pot and center the plant for visual appeal. Fill the space between the plastic container and the decorative pot's wall with lace, river stones, artificial moss or any other decorative material. Cover the smaller nursery pot and foam setting with the decorative material, if desired.