Growing Together: What's the best pot (for houseplants)?
There was a time when pot was either a container in which you made soup or grew flowers. It’s wise to choose our words more carefully now.
If I ask about your pot preference, I should clarify that I’m wondering whether you like clay, plastic or ceramic for your dieffenbachia.
Does it really matter what containers we use for our houseplants? A quick glance at Pinterest shows plants growing in everything from old shoes to polished brass. It might seem like a free-for-all, but the type of pot really can make a difference in how well plants grow. A houseplant’s container, which we can simply call its pot, is more than just a receptacle to hold soil. The container influences the health of the root system, which in turn affects the entire plant.
Pots can be divided into two broad types: those that breathe through their sides and those that don’t. Unglazed terra-cotta clay pots are the traditional breathable flowerpot, while plastic, glazed, ceramic and other materials don’t allow air and moisture to pass through. To simplify, it’s clay pots versus everything else.
Advantages of clay pots
- The porosity of clay allows air and moisture to penetrate the pot’s sides, and the fine feeder roots at the edge of the plant’s soil ball are able to utilize the extra oxygen, creating a healthy soil environment.
- Air movement through clay stimulates root development.
- Clay pots act like a wick to remove excess moisture from the soil, reducing the threat of over watering, which is a leading cause of houseplant decline. Houseplant owners who tend to over water usually find greater success with clay pots.
- Plants that require well-drained soil, such as cactuses and succulents, may be easier to grow in clay pots.
- Clay tends to pull soluble salts out of the soil, reducing damaging salt accumulation. The white residue that forms outside clay pots can be removed with a scrub brush and neutralized with a mixture of half water, half vinegar.
Other potting tips
- No matter the pot type, drainage holes are essential for allowing excess water to quickly exit the soil.
- Instead of growing plants in decorative pots, they can be potted into clay pots and slipped inside the decorative container. Check immediately after watering to be sure drainage doesn’t accumulate unseen in the outer container.
- Setting pots in visible saucers is the best way to detect drainage that can quickly damage plants if not discarded.
- It’s difficult to discard excess water from pots that have built-in saucers. Separate saucers are better.
- Houseplants can be successfully grown in most containers, but non-clay types require monitoring more closely, as clay pots are more forgiving.
Skip the drainage material inside pots
Adding rocks, pebbles, or broken pot shards inside the bottom of pots has a long history, but it’s best left out.
This from Washington State University: “Nearly 100 years ago, soil scientists demonstrated that water does not move easily from layers of finer textured materials to layers of coarser textured. Since then, similar studies have produced the same results. Therefore, the coarser the underlying material, the more difficult it is for water to move across the interface.
“Gravitational water will not move from a fine soil texture into a coarser material until the finer soil is saturated. Since the goal for using coarse material in the bottoms of containers is to keep soil from getting water logged, it is ironic that adding this material will induce the very state it is intended to prevent.”
For best drainage, just fill the pot top-to-bottom with quality potting mix.
Don Kinzler, a lifelong gardener, worked as an NDSU Extension horticulturist and owned Kinzler’s Greenhouse in Fargo. Readers can reach him at email@example.com.