Before the plants, before the design, before anything else: water has to get out of the bottom of the pot. A beautiful container without a drainage hole is a vase, and plants drown in vases. Everything else in this article is negotiable. That part isn’t.

The drainage hole is non-negotiable

Roots need air as well as water. In a pot with no exit, every rain fills the bottom with standing water, the air is pushed out, and the roots begin to rot, quietly, out of sight, while the top of the plant slowly wilts as though it were thirsty.

Found a gorgeous pot with no hole? Drill one, or use it as a cachepot: keep the plant in a plain nursery pot inside it, and lift it out to water.
A layer of gravel in the bottom does not substitute for a hole. It just raises the puddle closer to the roots.
Set pots on feet or risers so the hole can actually drain, especially on flat concrete. A pot sitting flush on a saucer of its own runoff is back to being a vase.

Potting mix, not garden soil

Fill containers with potting mix, the bagged stuff that feels almost too light. It is engineered to hold moisture and air at the same time, which is exactly what roots in a confined space need.

Garden soil (including our famous Upstate red clay) does not belong in a pot. In the ground, clay drains slowly but enormously; in a container it compacts into a brick that neither drains nor breathes. It also brings weed seeds and fungus along for free. The bag costs more than the shovel. Use the bag.

When to refresh the soil

Potting mix wears out. The organic material breaks down, the volume shrinks, and what remains compacts and sheds water. Signs it’s time:

Water races through and out the bottom in seconds, every time, even when the soil is not root-bound dry.
The soil level has dropped an inch or more below where it started.
The mix stays soggy for days after rain instead of drying evenly.

For planters we replant each season, refreshing is simple: pull the spent plants, loosen everything, and replace the top third to half with fresh mix. A full swap is worth doing every couple of years, or any time a planter has had a disease problem. Starting a new season in old, collapsed soil is the quietest way to waste good plants.

Size is a drainage decision too

Small pots are hard mode: they dry out in an afternoon, overheat in the sun, and give roots nowhere to go. If a planter fights you every single summer, the honest fix is usually not a different watering schedule. It’s a bigger container with a real drainage hole and fresh mix in it.