What to Put in the Bottom of a Calendula Pot? The Surprising Answer

 It’s a piece of gardening advice passed down for generations: before you add soil to a pot, put a layer of gravel, rocks, or broken pottery shards at the bottom to improve drainage. It seems to make perfect sense. Water hits the coarse layer and flows right out, right?

But what if this age-old wisdom is not only unnecessary but actually harmful to your calendula? The truth is, modern horticulture science has debunked this myth. To give your calendula the best chance to thrive, the answer to what you should put at the bottom of the pot is surprisingly simple: nothing but your potting mix.

This guide will explain why you should skip the rocks and focus on what truly matters for a healthy, blooming calendula.

The Old Myth: Why We Were Told to Use a Drainage Layer

The logic behind putting a coarse layer at the bottom of a pot was twofold:

1. To prevent the drainage holes from getting clogged with soil.
2. To create a space where excess water could quickly drain away from the plant’s roots.

While the intention was good, this practice is based on a misunderstanding of how water moves through soil in a container.

The Scientific Truth: The Problem with the “Perched Water Table”

When you put a layer of coarse material like gravel underneath a finer material like potting soil, you don’t improve drainage. Instead, you create something called a perched water table.

Think of your potting soil like a sponge. A sponge holds onto water until it becomes completely saturated, and only then will gravity pull the excess water out. When you place that “sponge” of soil on top of a layer of gravel, the water will not immediately flow down into the gravel’s large air pockets. Instead, the soil must become fully saturated with water first, right down to the last particle touching the gravel layer.

This means the water actually “perches” or pools at the bottom of the soil, right above the gravel. You have effectively raised the soggy bottom of the pot, forcing your calendula’s roots to sit in a swampy, oxygen-deprived zone—the perfect environment for root rot. Instead of helping, you’ve made the most dangerous part of the pot even closer to the roots.

Calendula

What Really Creates Great Drainage for Calendula

So, if gravel is out, what’s the secret to a happy, well-drained pot? It comes down to three simple, crucial factors.

1. A Pot with Excellent Drainage Holes

This is the single most important feature. Your pot must have one or more open holes at the bottom. This is the only exit route for excess water. If you’re worried about soil washing out, you can place a single piece of window screen, a coffee filter, or a curved piece of broken pottery over the hole—just enough to block the soil, not the water.

2. High-Quality Potting Mix

This is the real key to success. Never use heavy soil from your garden in a pot. Instead, fill the entire pot—from bottom to top—with a light, fluffy potting mix designed for containers. This mix contains ingredients like peat moss, coir, perlite, and vermiculite. These materials do two things perfectly:

• They retain just enough moisture for the plant.
• They create air pockets throughout the soil, allowing roots to breathe and excess water to drain freely all the way to the bottom.

3. Proper Watering Technique

Water your calendula thoroughly until you see water flowing out of the drainage holes. This ensures the entire root ball is hydrated and flushes out any salt buildup. Then, don’t water again until the top two inches of the soil feel dry to the touch. This simple cycle prevents the soil from ever becoming a swamp.

The Verdict:

Save the gravel for your driveway, not your plant pots. For a calendula that will reward you with a season of brilliant blooms, forget the filler. Fill your pot from top to bottom with a quality potting mix, ensure your drainage holes are clear, and let the pot do its job. It’s the simplest and most effective way to guarantee a healthy foundation for your plants.

Article copyright by GreenShip