Clay or plastic? That is a question often asked by gardeners throughout the year — and mostly during late winter, as we begin thinking about spring and wonder why our plants are not doing particularly well. We think that re-potting might be the answer, but it probably is not. There are many other factors that might affect plants and cause problems.
But let us talk about pots. For centuries, the only available containers for plants were either terracotta pots made from a clay-like soil, or from wood. Then, in the mid-20th century came plastic. It changed the whole dynamic. Let’s look at the whole picture.
I’m an old-fashioned gardener. I like using clay pots. That was not always true. When I was very young, before the days of child labor laws, my job in the family business, two or three times a year, was to crawl under the benches in our greenhouses and gather up the clay pots that had been tossed there after use. It was not a pleasant job. But I was 6 or 7 years old and there was no department to report my parents to.
I like clay, first of all, because it has a natural look. The natural terracotta “goes with” nearly any plant we place in it. When it is new, it is crisp and clean. As it ages and gathers that crusty white film or moss-green color, it becomes a center of attention. There is one advantage to clay that many of us old-fashioned gardeners like: It is porous and allows for the exchange of water and air to and from the soil ball. In essence, clay pots breathe. It is hard to over-water plants in clay pots. On the other side of it, plants in clay tend to dry out more quickly, and you will have to spend a whole lot more time in watering.
There are some special times that you should use clay. If a plant is going to be proportionately larger than the pot, the weight of the clay pot will add stability. I like clay on the patio; it blends more with the natural look. I will say that some of the newer kinds, colors and sizes of plastic are very interesting. On the down side, plastic pots are much less expensive than clay. Most of the clay we see in our stores is from Italy or the southern United States. One last note on clay is to be sure to soak your new pots overnight in water before using. If you do not, they will suck the moisture away from your soil ball. And, whether using plastic or clay pots, it is wise to scrub them before reusing to remove any possible disease, insect eggs or fertilizer buildup. Actually, I run my clay through the dishwasher, the one at the shop, before using.
We sure do use a lot of plastic pots these days. Growers use them because they are lightweight, cheaper to ship, nearly unbreakable and less damaged in shipping, and because they also dry out more slowly, that increases the necessary shipping time before plants dry out. Until the advent, recently, of decorative plastic containers, the old green or gray plastic pots were quite unattractive. But, after use, they are much easier to clean.
Plastic pots hold water better than clay. Some research shows that they stay moist nearly twice as long as clay pots. But this is a disadvantage for many home gardeners who tend to over-water. Many folks will remember that I have always said that more plants are killed by kindness than neglect. Over-watering and using too much fertilizer are most often the culprits. So, if you have a heavy hand with the hose, you better switch to clay pots.
In another column, I’ll add a few notes about decorative earthenware, glass and wood containers. All need to play a part in our decorative schemes.