Quality is important in everything we purchase, especially if we want the product to last. Containers for plants are no different.
Characteristics of All Quality Pots
Drainage Hole
All containers must have a drainage hole. Without one, the soil stays wet and roots rot and die. Putting a layer of gravel in the bottom does not make up for the lack of a drainage hole.
When purchasing a container sometimes the drainage hole has to be punched out. Be sure to remove the plug before filling it with soil.
For containers without drainage holes, use a drill to create one. The the larger the container, the more holes there should be to provide adequate drainage. Typical drill bits can be used to drill holes in plastic containers. Glass or ceramic bits can be used for terracotta, clay, or ceramic containers.
Trays, Saucers, and Double Pots
A tray or saucer to collect excess water is not required, especially for outdoor containers. They are highly beneficial for containers used indoors and in some outdoor settings to protect furniture and floors preventing stains, rot, or discoloration.
If you have a container you want to use, but it doesn’t have (or you don’t want to add) a drainage hole, use a double-pot system. Double pots (or cache pots) use the desirable container as an outer “sleeve” for a slightly smaller container with a drainage hole to set down inside. This allows you to get the drainage you need while using a container that doesn’t have a drainage hole.
Size
For outdoor containers, larger is often better. In many cases you have to balance the size with the cost to purchase and fill the container with potting soil. Containers always look smaller once placed on a deck, patio, or driveway so using larger containers can help keep things in scale with the outdoor setting. Additionally, smaller pots will dry out more quickly than larger ones. To reduce the burden of watering, select a larger container.
For indoor containers, bigger is not always better. It’s important to find the right balance between having a container large enough that it doesn’t always need watering but small enough so that potting soil and roots dry out in a reasonable amount of time and are not sitting for long periods in wet soil.
Cost
In general, the higher the price, the higher the quality but this metric is not a fool-proof one. Price is not always a reliable indication of quality. Some inferior products are high priced as well. Plastic containers are lower in cost than other materials like terracotta and glazed pottery. The cost you can afford is often a balance between size, material, and overall appearance. Be sure the container meets the needs of the plant (large enough, drainage hole, etc.) and then make a selection based on appearance and material.
Selecting High-Quality Clay Pots
Clay pots can be easily cracked and broken so it's important to select a sound pot instead of one with an invisible flaw that may crack easier. To check for soundness, hook a finger through the drain hole and tap the pot on its shoulder (the expanded rim of the pot). A good pot will ring like a bell (flawed pots will produce a flat or dull sound).
Clay pots are baked in kilns and get their strength from the duration and temperature at which they were fired. The longer and hotter they are fired, the better the minerals within the clay will harden or vitrify. When selecting pots, you can easily detect low quality pots by running your fingernail across the pot. Low quality pots scratch easily.
Walls of inferior pots begin to flake, pit and crumble as mineral salts leach through. Durability is affected by the purity of clay used. All clay contains lime impurities. In quality pot construction, the lime is filtered out of the clay before manufacturing. Inferior pot manufacturers usually don't bother with this process and allow lime deposits to remain. Lime particles absorb more moisture than clay particles which causes blistering and flaking of the pot surface. If the pot you are selecting has white, gritty spots on the surface, pass it by, it's an inferior pot.
Clay that contains sand is made into quality pots as long as the firing process is done correctly. Pots properly handled will be dense and ceramic-like. Improperly handled pots will have a sandy texture and are likely to crumble away with time.
Selecting High-Quality Plastic Pots
The quality of plastic pots can be determined by checking the thickness and flexibility of the pot walls. Pot walls should be thick enough to support the weight of the wet soil they will hold. The larger the pot, the thicker the walls should be. Flexibility can be checked by squeezing the pot. Plastic pots should be flexible enough to withstand being bumped or dropped without breaking.
Generally speaking, the durability and thickness of the pot increases with increasing cost. If planning to use a particular plastic pot outdoors, check the label for an indication that it has been protected with ultraviolet light inhibitors. These inhibitors will help protect pots from fading and becoming brittle. The label may not say specifically that it was treated; however, if labels recommend using the pot outdoors, it probably has this protective treatment.
More Information
- Growing Annuals in Containers (PDF)
- All About Container Gardening
- Making Mixed Containers (video)
- How to Select Quality Plant Containers
- How to Clean and Disinfect Plant Containers
- Container Vegetable Gardening (PDF)
Photo credits: Vladimir Liverts/AdobeStock; Johnny/AdobeStock; Ana BG/AdobeStock