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Linda Naeve, Reiman Gardens, (515) 294-8946,
Jean McGuire, Continuing Education and Communication Services, (515) 294-7033,

Reiman's Pick for the week of March 29, 2004

Polystyrene Planters Are More Than Plastic Pots

By Linda Naeve
Reiman Gardens Extension Coordinator

Designers and inventors have found creative ways to duplicate countless items to the point where one cannot guess the authentic from the imitation. There are many reasons and uses for these imposters, such as the long-lasting, just-picked look of silk flowers, the convenience and ease of installation, reduced cost, or availability of simulated compared to natural products. Silk flowers, plastic boulders and other synthetic landscape materials often appear so realistic that you have to touch them or knock on them to determine if they are artificial.

This week's Reiman's Pick is a group of beautiful and useful look-alikes that many gardeners are using - polystyrene planters. These pots or containers come in a wide assortment of sizes, forms, styles and colors. Some resemble clay or terra cotta pots, while others have a poured or sculpted cement look. They do not look at all like their cousins - the old, typical plastic pots - and are much stronger.

Polystyrene is a versatile and common plastic. It is likely that every day you use several products containing polystyrene. In its rigid, durable form, it is used for appliances, toys, compact disc "jewel cases," audiocassette cases, housing for televisions and computers, and some of the molded parts inside your car. In its soft form, it is designed as insulation and foam packaging, Styrofoam™ is a brand name of polystyrene foam.

Although clay pots are great for growing plants and have an "earthy" appearance, they have some limitations not found with polystyrene containers. Terra cotta containers are heavy and difficult to move when filled with potting soil. Polystyrene pots, however, are extremely lightweight and portable, even when filled with soil and plants. This enables gardeners to place and rearrange large containers on decks and throughout the garden.

Clay pots should not be left outdoors through the winter in northern climates because soil and moisture in the pot will freeze, causing them to crack or chip and flake away. Clay pots should be emptied and stored in a shed or garage. Large, heavy clay pots make this a difficult chore. Although the polystyrene containers won't chip and flake away, they should also be emptied at the end of the season and stored in a protected location.

Polystyrene containers will look as new as the day you bought them after several years. Clay planters, on the other hand, do not retain their look due to salt deposits and algae growth that accumulate on the outside. For gardeners who like the appearance of used clay pots, some polystyrene containers are designed to look old and weathered.

Regardless of the manufacturing process used to create a pot, there is one requirement for all of them - drainage holes. Openings on the bottom of the container are essential to allow excess water to move out of the soil. Without drainage holes, water accumulates in the soil, reducing needed oxygen for the roots and causing root rots. Many polystyrene containers do not have drainage holes so you will need to drill a few holes evenly spaced apart in the bottom.

Reiman Gardens at Iowa State University is noted for its beautiful assortment of containers and planters filled with attractive combinations of plants. Check out the Web site at for information on workshops that will help you create and grow beautiful container gardens.


Editors: A color photo, suitable for publication, is available at right. Click on the thumbnail photo to go to the fullsized photo. The picture's fullsize photo is 412K.

Caption: polystyrene pot

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