What to Put in the Bottom of a Planter for Drainage

Updated: May 04, 2024

What's the best way to fill a plant container? Here are several tips on economical and practical methods to fill planters of all shapes and sizes.

Growing vegetables, herbs and flowers in containers opens up the gardening world, whether you only have space on a patio or wish to keep certain plants close to the kitchen. Whatever the size of the pot, proper drainage is imperative for healthy plants.

“Drainage is essential for potted plants because it prevents water from accumulating at the bottom of the container, which can lead to root rot, eventually suffocating the plant. Proper drainage ensures that soil remains aerated and prevents roots from becoming waterlogged. This encourages deeper and stronger root systems and healthier plants,” says Carrie Spoonemore, the co-creator of Park Seed’s Seed to Spoon gardening app and veteran organic gardener.

What To Know About Filling the Bottom of a Planter

“The best containers for potted plants have drainage holes at the bottom,” says Spoonemore. The right size of drainage holes is also important because they need to be large enough to allow water to readily flow out without losing the planting medium.

Most store-bought planters will already have holes adequately sized for that container. But for some decorative containers, you have to drill your own.

How to Drill Drainage Holes in a Planter

If you choose a planter without drainage holes, drill 1/4 to 3/8-inch holes roughly five inches apart. For ceramic planters, use a masonry drill bit, beginning with a 1/4-inch bit, then work up to 1/2-inch, being careful not to exert too much pressure that would crack the ceramic. Wear gloves and eye protection when drilling.

What To Put at the Bottom of a Planter for Drainage

Empty Water Bottles or Milk Jug

To add lightweight bulk to larger planters, add empty, capped water bottles or milk jugs to take up space without adding weight.

Pros:

  • They’re free.
  • Not many other ways to reuse them

Cons:

  • You’ll still end up throwing them in the trash.
  • Can be cumbersome if you’re using a lot of bottles

Kitchen Colander

A plastic colander takes up space while allowing water to drain through the holes.

Pros:

  • It’s simple and easy.

Cons:

  • Have to either buy a colander or use one from the kitchen
  • Some soil will sift through the holes.

Large Rocks

If you live in a windy area like I do where the wind often blows upwards of 50 mph, a few large rocks — around the size of a softball or larger — in the bottom can keep a container from blowing over.

Pros:

  • They’re usually free.

Cons:

  • It can make the container cumbersome to move.
  • You must take extra care not to cover drainage holes.

Air-filled Packing Pillows and Bubble Wrap

Ever wonder what to do with the air-filled packing pillows often used in shipping packages? They are a terrific way to take up space in the bottom of a container. You can also use folded bubble wrap.

Pros:

  • Both of these materials are free.
  • They’re lightweight but take up space.

Cons:

  • You must be careful not to cover drainage holes.
  • The pillows can puncture if you accidentally hit them with a sharp tool.

Pool Noodles

Pool noodles can be used in all sorts of nifty applications. And they can make a customizable filler for your planters.

Pros:

  • You can cut them into sizes that best fit the container.
  • They lighten the container.

Cons:

  • A large container might need a couple of pool noodles, and you might need to contort it to take up the most space.

Empty Plastic Pots

I typically have ample gallon-sized plastic pots after a spring foray at a local nursery. Instead of stacking them in the garden shed, I place one or two upside down in the bottom of a large container. Typically, holes in the bottom of the plastic pots allow moisture to drain through to the main container’s drainage holes.

Pros:

  • They’re usually free.

Cons:

  • They’re best used on large containers because they are taller and narrower.

Whole or Crushed Seltzer or Soda Cans

Another option to take up space at the bottom of a container is to use either whole or crushed, empty soda cans. Dump out any of the seltzer or soda from the can ahead of time. If you’re using a whole can, place it upside down to keep the soil from going inside of it. Or just add a layer or two of crushed cans.

Pros:

  • It’s a good way to use cans before recycling.

Cons

  • Once you empty the planting containers, you have to rinse them off before recycling them.

FAQ

What’s the best drainage for potted plants?

Planting Spring Flowers in Terracotta Potscjp/Getty Images

The best drainage is a good, well-draining soil mixture and adequate holes in the bottom of the container.

What’s the cheapest way to fill planters?

“One of the most economical methods for filling planters is to make your own potting mix using a combination of inexpensive materials such as garden soil and compost. This DIY approach can be more cost-effective when planting in bulk, building a raised garden bed, using larger planters, or filling multiple containers,” says Spoonemore.

Can you put rocks or gravel in the bottom of a planter?

“Putting rocks or gravel in the bottom of a planter is generally unnecessary, as this practice can impede drainage rather than improve it. Water tends to accumulate between different soil layers, leading to water-logging in the root zone,” Spoonemore notes.

Is it okay to put styrofoam in the bottom of a planter?

“Using Styrofoam at the bottom of planters is not recommended. It doesn’t provide drainage and may eventually break down into microplastic particles, posing environmental concerns,” says Spoonemore.

What other materials should you not use at the bottom of a planter?

“Materials that should be avoided at the bottom of a planter include rocks, gravel, and broken pottery shards. These items can create a perched water table, leading to water-logging and root rot,” she says.

What should you put under planters indoors?

Spoonemore says, “You can use saucers or trays underneath planters to catch excess water and prevent it from leaking onto floors and furniture. Alternatively, you can place planters on waterproof mats or trays specifically designed for indoor gardening to protect surfaces from moisture.”

About the Expert

Carrie Spoonemore is the co-creator of Park Seed’s Seed to Spoon gardening app. She and her husband, Dale, created their urban Oklahoma garden nearly a decade ago and have developed methods to efficiently grow organic food for their family and friends in a small space.