Planter Box Bottom Materials For Better Drainage [2024 Updates]

Have you noticed that your plants sometimes display wilting,  yellow leaves, or leaf drop? Have you removed the dead plant and discovered mushy lower stems and black or slimy roots? If yes, then your plants have probably died from root rot, usually caused by excess water pooling in the base of your planter. In addition, does your planter leave a ring of water stains on the patio? 

These are signs that your planter’s drainage needs improving. Suitable drainage materials at the bottom of your pots can mean the difference between thriving, healthy plants and a waterlogged mess.

Apart from aquatic plants, it is essential that your plants’ roots do not sit in pooling water. Roots exchange oxygen and carbon dioxide with air, which will be interrupted if excess water blocks air pockets in the soil. This can lead to root rot that will very likely kill your plants. However, in addition to drainage materials, it is also vital to ensure that you have drainage holes in the base of your planter, as this, too, will ensure that excess water will drain away.

This article will explore practical solutions to ensure your raised garden bed or planter box has excellent drainage.

Why Do Planters Need Bottom Materials For Drainage?

We now know that drainage in the bottom of planters enables airflow around the roots. However, it also allows the roots of your plants to uptake and absorb essential nutrients from the soil.

This approach applies to indoor plants also.

Without adequate drainage, water collecting at the bottom of the planter can become stagnant and cause fungal growth in addition to root rot.

Planter Box Bottom Materials For Better Drainage

Using materials like broken pot pieces, stones, or gravel at the bottom of a planter, gardeners can create a barrier that allows water to drain away while preventing soil loss and blockage of drainage holes. However, other methods and adequate drainage materials should also be implemented.

Firstly, ensure your planter has adequate drainage holes to allow excess water to escape. Some planters, especially wood, benefit from a slight elevation (even on small risers) to prevent water from pooling against the bottom and rotting the wood itself.

Next, choosing the best materials and knowing how to fill a wooden planter box is essential.

Here’s a rundown of the best materials for creating excellent drainage at the bottom of your planter box:

Landscape Fabric

This popular method is a permeable material that allows excess water to drain away while keeping your essential potting soil in place. Landscape fabric is durable and also widely available.

Hardware Cloth

This sturdy metal mesh does a fantastic job of promoting drainage. Its structure also helps deter unwanted animals from trying to burrow into your planter from underneath. It is best for large or heavy planters.

Soda Cans

Soda cans are ideal drainage material in large planters and perfect for cans that would have otherwise been thrown out. Also, they are cheap or free! Use whole or crushed cans and simply place them upside down to prevent soil from filling the inside. 

Check some of the cheapest ways to fill planters.

Other Options

• Gravel or Pebbles: These are classic drainage layer materials. While efficient, they add significant weight, especially in larger planters, and may develop a perched water level.
• Broken Pottery Shards (Crockery): Traditionally used over drainage holes, these provide some added drainage space but are less effective than mesh-like materials.

Packing Peanuts: While they offer decent drainage, they aren’t the most eco-friendly choice and can break down over time. They are better used for filling the bottom of large planters to reduce soil volume than as a dedicated drainage layer.

Planter vs Raised Bed: Which One Offers Better Drainage

If excellent drainage is your top priority, then raised beds are often the better choice. However, with the proper techniques, planters can also provide suitable growing environments for many plants.

Benefits of Raised Bed

• Position and Design: Raised beds are directly on the ground, allowing excess water to drain naturally into the surrounding soil through appropriate bottom materials. Planters, especially those on solid surfaces, can trap moisture at the bottom.
• Material: Many planters are made of non-porous materials like plastic or glazed ceramic, hindering water movement. Raised beds are often built from more breathable materials like wood or have open sides, allowing for better airflow and evaporation.
• Customization: You have more control over the soil composition in a raised bed, creating a well-draining mix ideal for your plants. Planter soil can become compacted more easily.
• Root Space: Larger raised beds allow for better root development, which helps plants withstand occasional waterlogging better than those confined to a planter.

However, planters can still offer good drainage with these precautions:

• Drainage Holes: Ensure your planter has sufficient drainage holes at the bottom.
• Elevated Planter: Raise the planter slightly off the ground to prevent water from pooling around the base.
• Well-Draining Soil: Use a lightweight potting mix specifically designed for good drainage. Avoid heavily compacted garden soil.
• Material Matters: Choose porous materials like terracotta when possible.

Either option allows you to fill in with soil suitable for the type of plants you intend to grow.

However, soil from garden stores can be expensive, especially for raised beds and larger planters. 

For raised beds that will take a fair amount of filling, consider using cans for drainage and overlaying with newspaper, cardboard, grass clippings, compostable kitchen food scraps, or dry leaves to bulk up. This overlaying will eventually rot down and add essential organic matter and nutrients, as well as attracting earthworms. Add a top layer of compost six to twelve inches deep. The first season of planting should be with plants with a shallow root system. In the second year, the organic matter will have started to rot down, and the bed will need to be topped.