Choosing Containers, Pots and Vessels for your Plants
By Laurelynn Martin and Byron Martin
Containers, pots and vessels for plants have been around for thousands of years. They have become a well-loved art form and many times they are the focal point in garden rooms, patios and windowsills. In the United States, a glazed flowerpot dating back to 1750 from Norwich, Connecticut was thought to be the earliest pot in the U.S. but then a three-inch clay pot in a Spanish settlement on Parris Island, SC was unearthed dating back to 1569. The earliest flowerpot on record was first documented in 317-287 BC Athens, Greece. Whether beautiful hand thrown, rolled-rim terra cotta pots from Italy, glazed orchid pots from England, colorful plastic pots from China or earthen pots from the United States, we know one thing for sure and that is the obsession with pots is worldwide. There is no question that size, shape, color and form are players in the container gardening scene but our focus in this article is about the advantages and disadvantages of each container and their effects upon the plant.
Purpose of Containers
Containers hold the root system and the potting media together. A container provides a closed environment for the plant to grow and maintain its root zone structure while allowing the gardener the freedom to move the plant into different growing areas. All good containers MUST have one or more drainage holes in the bottom of the pot. Otherwise, the soil becomes too wet and can be a haven for disease organisms or fungus gnats. For most plants, providing a wet and dry cycle, similar to environmental conditions plants experience in nature is best. For example, growing a lemon tree in Connecticut is only an option because it can be grown in a pot. The ability to move the plant both indoors and outdoors or grow the plant in an area where garden soil is not available makes growing plants an enjoyable hobby for people in all climate zones. Also, growing a plant inside on a windowsill allows you to control the environmental conditions.
Plastic pots have many advantages. They are cheap, relatively durable, lightweight and for the consumer as well as commercial grower, come in a vast array of sizes, colors and forms. Its only disadvantage, other than the environmental waste issue, is that a plastic pot can hold soil moisture for longer periods of time. For plants that have high water demands, this is advantageous, but for plants that need a quick dry down, high mositure can be detrimental for good root health.
Clay pots give the gardener the ability to more accurately manage soil moisture. We have found when growing in clay, overall plant health is better, especially for plants with sensitive root systems. Clay does take a little more attention to watering, as the dry down is usually quicker. Clay pots allow moisture to escape from the entire surface of the pot so it provides better overall soil aeration. We still use clay pots for some of our stock plants that are sensitive to root disease. If a home gardener is interested in optimum root health and is attentive to watering, then we highly recommend growing in clay pots. Some disadvantages of clay or terra cotta are that they break easily and they tend to be heavy in weight. When the plant gets big and the pot size is over 10 inches, they are harder to move around. If large clay pots filled with soil are left outside in freezing weather, they can crack and break.
Glazed ceramic pots
Glazed ceramic acts like clay and plastic combined. They are aesthetically appealing but act like clay when it comes to weight and breakage. And for root health, they have a similar environment as plastic because they can’t breathe or release moisture.
In times past, wooden barrels and troughs were often used for containers. Today, we mostly see wood used in window boxes and other large outdoor containers. Although wood is porous and does absorb moisture, it also lets more moisture evaporate than plastic but not as quickly as clay. Wood may be a good choice for plants on a patio or deck. However, a wooden container will rot over time. Also, weight becomes an issue when you need to move your container. Pressure treated wood can be used so the container doesn’t rot and as long as the pressure treated wood is copper based, it doesn’t seem to hurt the plant. However, if the wood is treated with creosote, it will kill the plants.
Cement containers are sometimes produced using molds and forms. However, they are heavy, break often and will crack in subfreezing weather. Also, root health can be an issue unless the cement has a drainage hole or you put a planter within a planter.
Many large decorative containers are made from fiberglass. It’s lighter than cement and doesn’t crack if left outside in freezing temperatures. Make sure your container has drainage holes for good soil aeration.
Jardineres or Cachepots
Jardineres are decorative garden plant containers made of pottery, porcelain or glass. They were especially popular during the art pottery craze when brands like Roseville, Rookwood, or Weller pottery were highly sought after for display in garden rooms and sunrooms. Cachepots are outer decorative pots, usually for smaller plants. The main thing to keep in mind when using either jardineres or cachepots is that you need to be careful not to overwater. You don’t plant directly in the jardinere or cachepot but simply drop a potted plant inside. Sometimes it’s helpful to put rocks, gravel or other drainage material in the bottom and place the potted plant on top of the drainage material.
Woven or cloth container bags
Woven bags are relatively new containers and in some cases can work quite well for summer growing. Nurseries often use woven containers for tree production. They have great drainage, are light weight and when the season is over can be emptied and stored in a small space. Obviously, cloth does not work for indoor growing or windowsills since the pot drains water from the entire surface of the container.
Many biodegradable pots are made from rice hulls. These are much like plastic because they hold more moisture in the pot. After a few years of service, these pots break down and then can easily be composted. Environmentally, biodegradable pots are a good choice but they are more expensive than plastic.
Peat pots are still used to grow plants but these containers are really suited for short term growing as they break up easily as the pot ages. They do have great drainage and the entire plant and pot can go directly into the soil or potting mix. Also, these are great for the environment and a good choice for starter plants.
Tin was a choice container for many years. Tin disappeared as plastic took over. There are some decorative tin cachepots on the market today.
Recently, we ran a contest called the Creative Container Contest. Contestants used any vessel that would hold soil and had a drainage hole for root health. Some of the more popular containers were rubber boots, an old barn lantern and even a used paint can. Containers are attractive accents to any garden. Remember to drill a hole in the bottom so water can drain. Also, depending on the ability of the pot to wick away moisture, you may have to pay closer attention to the soil.
Sources:A Potted History of Gardening by Adrian Higgins