Growing in Containers: Clay or Plastic?

Ideally, vegetables should be grown in the ground. However, for those of us living in apartments and condos, that may not be possible. While I do have a scrap of land between my condo and the parking lot, the lawn maintenance people are somewhat indiscriminate in their use of weed-killer. There is the fear that the chemicals may be taken up by the root system of any vegetables growing nearby. That led me to growing in containers. After all, anything growing in a pot is, by definition, not a weed, right? (Definition: Weed – any plant growing where you don’t want it to.) The hope is that being in containers will protect them from the spray.

Clay or Plastic?

I originally started with clay pots. And when I say clay, I’m talking about old-fashioned, unglazed terracotta. Rockin’ it old school. I like them because they have a classic look, but after a winter or two they were cracking or flaking from having been frozen, thawed, frozen, thawed, etc.. If you live where the winters get below freezing, they don’t last all that long and are expensive to replace – particularly in the larger sizes. The problem is that clay is porous. Water wicks through it and evaporates off the outer surface. However, when the temperature drops below freezing, any water in that porous clay may freeze. Water expands when it freezes and this can cause the pots to flake or crack.

Clay’s porosity can be both good and bad. If you’re the type who habitually over-waters their plants, clay is more forgiving. Some of the excess will evaporate through the sides of the pot. The downside of that is that clay dries out faster and your plants will need watering more often.

After losing several clay pots to cracking, I began buying plastic pots in the same terracotta color. Since plastic is not porous, it does not dry out as fast. I was a little concerned that the plastic, exposed to sun and extremes of temperature, would deteriorate and crack as well. I’ve been surprised at how well they’ve held up. Yes, a few have begun to crack, but I’ve gotten 5-6 years of use out of them before they did. Also, plastic pots are lighter when you have to pick one up and move it, soil and all.

What size pot? Growing vegetables in containers – especially tomatoes – calls for a large volume of soil – 16-20 inches across the rim is a good size for plants with a large root system.  Leaf vegetables like lettuce can go in smaller containers, maybe a 10″ or so.


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