Packing peanuts can lighten large planters

By Mary Boldan, Mary Moisand and Donna Siemro
Posted3/17/2012 2:54 AM

Q. Last year I had a large planter on my front porch. Since I had to use a lot of potting soil to fill the planter, it was very heavy to move, I heard that you can use Styrofoam peanuts as a filler in large pots. Is this true?

A. While large planters can make a stunning visual display, they need a lot of potting soil which in turn, can be expensive and make it difficult to move the planter. Also, most plants rarely need that much soil to survive. Using a filler, such as Styrofoam peanuts at the bottom of the container makes the pot lighter, so it's easier to move while also saving you money on potting soil.


Since the peanuts have an irregular shape, they do not pack together quickly beneath the soil. These spaces provide air pockets, which can supply oxygen to the soil, as well as plenty of space for moisture to drain. You may want to place a sheet of landscaping fabric over the peanuts before adding the soil. The fabric helps keep the soil from trickling between the peanuts and compacting while still allowing moisture to drain.

If you plan on repotting the plants at a later date, you may want to put the Styrofoam peanuts in net bags, such as from oranges or onions, and tie them closed. That way, when you repot the plants, it is easier to pull out the peanuts.

Finally, there are a lot of packing peanuts that are now being produced with corn starch-based materials that easily dissolve in water (biodegradable) when thrown out. So make sure you are using the traditional Styrofoam peanuts and not the biodegradable ones as they will melt away with water and you have nothing left.

• Provided by Mary Boldan, Mary Moisand and Donna Siemro, University of Illinois Extension Master Gardeners. Send questions to Ask a Master Gardener, c/o Friendship Park Conservatory, 395 W. Algonquin Road, Des Plaines, IL 60016, (847) 298-3502 or via e-mail to

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