Terra cotta, ceramic, plastic? What is best for your plants?

When you’re standing at the garden center in front of dozens and dozens of container pots, it’s not difficult to be absolutely flummoxed. Are unfinished terra cotta containers the best choice? Glazed ceramic pots? Are plastic, foam or fiberglass containers a better option? It’s enough to make a gardener want to hide their head in the dirt.

Mosser Lee is here to help you make the right decision for your plants, your environment and your esthetic needs.

Terra cotta pots – pros and cons

Terra cotta pots are made from a natural, porous material which can help roots exchange oxygen and moisture. When you water plants in terra cotta pots, moisture is wicked away by the clay, which helps prevent soggy roots, fungus and insect infestations. When you need moisture to stay close to roots longer, mix your potting soil with long-fibered sphagnum moss in a 1:1 ratio. This will also enable you to water less frequently.

If you don’t have time to water often, select plants that like drier, hotter conditions for your terra cotta plants, as terra cotta can get very warm. Enjoy cacti and succulents, avoiding water-loving edibles and annuals.

The burnt orange color is a classic look that complements any décor and is available in a wide variety of shapes and sizes. Terra cotta pots can be used indoors and out.

Terra cotta is relatively inexpensive, but beware of cheap terracotta which will chip, split and break easily. Make sure your terra cotta selection is high quality by tapping it with a spoon while it’s upside down. Good quality terra cotta will make a bell-like sound, lower quality will produce a dull thud.

Larger pots are extremely heavy and difficult to move once planted. For this reason, they need to be carefully sited before filling and planting. Terra cotta pots do need careful tending outdoors, especially in winter. Pots will need to be moved into a garage or basement, or carefully wrapped to prevent freezing and breaking. You may find your pots turning colors as minerals and nutrients in your water and soil are absorbed by the clay. If this mottled white or green patina bothers you esthetically – it does not harm your plants – you’ll need to empty the pots and then scrub them with a solution of 1 part vinegar to 3 parts water.

Cracked terra cotta pots are often used within the garden as design elements. They can be crushed to be used as mulch or foundation for a pathway.

Ceramic or glass pots – pros and cons

Ceramic pots are clay pots, often terra cotta, coated with a layer of glaze which is a hard, waterproof lacquer. That glaze helps the soil stay moist longer. Glass will have the same advantages and disadvantages as ceramic.

Ceramic and glass containers are a more sealed environment and will not provide circulation of air or oxygen.

Often, ceramic pots do not have drainage holes which can make watering very tricky. Few plants like waterlogged conditions; even bog plants need slow drainage. Outside, a few days of rain can drown plants completely. Inside, place a drainage layer at the bottom of the pot before filling with soil and planting. This could be a layer of larger rocks, or a jumble of crushed plastic containers, somewhere for water to sit without touching the roots. Watering must still be done frequently and sparingly.

Avoid this by buying ceramic pots with drainage holes and using the 1:1 mix of potting soil and long-fibered sphagnum moss.  

Ceramic pots are desirable for their wide variety of colors and vibrant patterns. Ceramic containers can be used indoors and out.

Ceramic pots can be very expensive, but used pots found at thrift store and yard sales can be reused when emptied and thoroughly scrubbed with a solution of vinegar and water to kill any lingering bacteria. Large ceramic pots are also very heavy, so positioning must be firmly decided before filling and planting. Outdoors, they will require the same winter care as terra cotta. Because of the glaze, ceramic pots do not acquire the nutrient and mineral patina that terra cotta pots do.

Plastic pots – pros and cons

Plastic containers are everywhere, in so many shapes, sizes and colors. Plastic pots help retain more moisture much longer but can get very hot, damaging plants.

Plastic pots, along with pots made of foam or fiberglass, are very cost effective and extremely light weight. Plastic pots can be used indoors or outdoors, but are especially useful in rooftop gardening, where weight is a major concern. When buying plastic containers, make sure they have drainage holes or ensure you can drill drainage holes easily and safely to avoid soggy roots and drowned plants.

Plastic containers are sturdy and do not break easily, but may crack in very cold weather. Some gardeners hesitate to grow edibles in plastic plants, but researchers believe growing in plastic is safe, and plastic molecules too large to transfer in a plant’s vascular system from soil to roots to fruit. If this is still a concern, seek out light-colored containers that are BPA-free and keep them out of direct sunlight.

Plastic containers can be difficult to recycle. When plastic containers have become scratched or damaged, the thrifty gardener can sink the plastic container in the ground and use it as an isolated area to plant things that spread by runners or extensive root systems; the sunken pot will keep these plants contained. It can also be used as a container for plants that need soil amendments that won’t wash away. Blueberries, with their need for acidic soil, can be especially fruitful when grown in sunken containers.

Whichever you contain you choose, you’ll need a soil cover to keep your plants robust and thriving. Many gardeners opt for sphagnum moss, Spanish moss, reindeer moss, available in a variety of colors, or sheet moss. The amazing capacity for moss to hold water will keep moisture in the soil, helping you water less frequently and your plants to stay healthier. After installing your plants, tuck the moss around the stems; do not put any type of moss or ground cover on top of leaves.

The containers you choose should fit your plants’ needs, your budget and your esthetic sensibilities. Using a combination of terra cotta, ceramic and plastic may be your best solution, depending upon location, plant type and available light. Grouping a selection of terra cotta pots around a large and dominant foam pot that mimics terra cotta can be a perfect focal point in your beautiful and healthy garden.