What Can I Use to Fill the Bottom of a Large Planter? - Home Stratosphere

What Can I Use to Fill the Bottom of a Large Planter?

Soil is expensive, and filling a large planter can be costly. The good news is there are many materials you can use to fill your planter. These can add or reduce the weight of your planter. The most popular options are rocks, packing peanuts, and old 2 litre bottles.

A row of large colorful pots.

Large planters are amazing. They are a great statement piece. They allow for larger plants that are great for your home’s air quality as well as aesthetics. Maybe you have a plant that needs to be repotted in a large planter. In my case, the planter came first.  I was at the store, minding my own business, and it called to me. I had to have it. So, in addition to finding the right plant to go in it, I knew I needed potting soil.

Potting soil is expensive, and it takes a lot to fill a large planter. I realized the bag I had purchased wouldn’t be enough to fill the planter. I started researching and learned that there are many things you can use to fill the bottom of a planter.

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How and Why?

Stacks of small terracotta plant pots on display.

Before you fill your planter, you’ll need to know how much soil your plant needs to grow. Generally, the bottom 1/4 to 1/3 of your planter will be filler. Research your plant online or ask your local garden center what the root depth of your plant is. You’ll want to have at least that much soil for your plant to grow.

Other than the obvious, it saves you money on potting soil, there’s an advantage to using a filler. Lightweight materials can reduce the overall weight of your planter since they are lighter than soil. Your planter will still be heavy, but not as heavy as filling it completely with soil. It can also aid in drainage.

Drainage is sometimes overlooked. Every plant in a container needs drainage. You may think that not having drain holes means you have to water less often, and you are correct. However, if you tend to overwater, your plant will get root rot. If your plant is outside and it rains heavily, your plant will get root rot. When selecting a material, it’s important to make sure that it allows drainage.

If your planter doesn’t have drainage holes, I highly recommend that you create a few. You can easily create holes in a plastic or resin container with a standard power drill. Just drill a few holes into the bottom of the planter. If you are concerned about cracking, apply a few pieces of artist or painter’s tape where the hole will be.

For a clay pot, you’ll want to use a masonry drill bit. Start with 1/4 inch and work up to 1/2 inch. Drilling the hole too big at once can crack the clay. You’ll need at least four drain holes. Six drainage holes are ideal for large planters.

Light Materials

Light materials are ideal if you want to decrease the weight of your planter. If you plan on moving it from one area to another or indoors and out, reducing the weight is a good idea. If you are using food or drink containers, be sure that you rinse them well before use. You don’t want to add food particles to your planter. This could cause bacteria, mold, foul smells, and pests. These materials can be combined to get a good fit.

Recycle Old Items

A textured exterior wall with hanging potted plants and displays made of recycled materials.

Items that are destined for the trash can be used in your planter. Just make sure they are clean first.

These include:

  • 2-liter bottles
  • plastic containers with lids or turned upside down
  • milk containers
  • egg cartons
  • crushed soda cans (rinse before crushing)
  • tin cans

Foam and Packing Materials

A vase in a box protected by foam packing peanuts.

You can use packing materials, foam balls, or floral foam for your container. Floral foam holds water, which can allow plants to go longer between waterings without the risk of rot.

You can use:

  • Foam blocks
  • packing peanuts
  • Floral foam
  • styrofoam coolers
  • Plastic or styrofoam cups

Natural Items

A close look at a bunch of wood chips on the ground.

Natural items can be used for your planter as well. Be aware that these will break down over time. This isn’t harmful to the plant, but it will compact itself as it breaks down. If you plan to use it for seasonal planting or eventually repot, this is a good option.

Natural items include:

  • wood chips or mulch
  • twigs and branches
  • pine cones
  • leaves
  • coconut fiber
  • peat moss

Miscellaneous items

An old vacuum cleaner recycled into a flower pot.

These are a few other items that you can use in your planter. Generally, you can use nearly anything in your planter, as long as you follow the dos and don’ts to come.

Miscellaneous planter fillers include:

  • Plastic Easter eggs
  • smaller flower pot turned upside down
  • Metal pot turned upside down
  • plastic or ceramic cups or bowls turned upside down
  • clay balls (sold as a soilless media option)

Heavy Filler Materials

A large rock basin filled with rocks.

If you don’t mind a heavy planter, or even prefer it to be heavy to reduce the risk of tipping, you can use heavier materials. These have the advantage of not settling or degrading over time, so it’s a good permanent solution.

Heavy filler materials include:

  • Rocks (gravel and small to medium size rocks)
  • Large rocks
  • Wooden sticks or logs
  • Broken ceramic or cement
  • Sand (can compact and mix with the soil)

Dos and Donts of Filling a Planter

An elegant pedestal planter with three different plants on it.

Do ensure that your material will not negatively react with the soil or your plant. Avoid items that have chemicals or dye that will get into the soil. Avoid items that can introduce bacteria or biodegrade very quickly.

Do make sure that the material allows for proper drainage. If you use something like a pot or bowl, be sure its turned upside down so that it doesn’t collect water. Using items that retain water can cause root rot in your plant or bacteria because the water stagnates.

Do mix materials. Mixing materials can create a better fill. Using small items like gravel along with larger items like large rocks or cinderblocks will help create an even layer so the soil stays in place.

Do use landscaping fabric if you want to provide an extra layer of protection so your soil doesn’t fall into the filler material.

Don’t put items with food or drink residue into your planter.

Don’t use items that may be contaminated with bacteria.

How to Plant in a Large Planter

A large square planter filled with compost soil.

You have your plant, your soil, and your filler materials. How you plant your plant will have an impact on its health, so it’s important to do it correctly. If the planter is previously used, you’ll want to wash it before using it. Make a solution of one part bleach to nine parts water and rinse out the pot to ensure there’s no mold or bacteria. If it’s a new planter, give it a good rinse with hot water, or use the bleach solution.

Next, decide where you want your planter to go. You may want to move it around the area for a few days to see where it gets the right amount of sunlight. It’s much easier to move before you plant.

Make sure the pot has drainage holes. If you are using it inside, you’ll need to place something under it to catch excess water. The areas of the pot with drainage holes should be slightly elevated from the ground to allow for drainage. Most pots are designed this way. If yours isn’t you can place a few shims on the outside edges to create a small gap.

Place your filler material inside the planter. If you’ve chosen to use landscaping carpet, put that in on top. If you don’t have landscaping fabric, you can place the filler items in pantyhose to create a barrier between them and the soil. Plastic grocery bags or cheesecloth would also work.

Mix the fertilizer into the soil if you are using any. Then wet the soil. You can do this in a wheelbarrow, a bucket, or even in the bag if you plan to use the entire bag. You’ll want it to be moist, but not soggy.

Begin placing the soil into the pot. Place about half the soil then press it down, especially along the edges. Place your plant into the planter and keep adding soil. Press it down as you go. You want the soil to hold the plant in place. Leave at least four inches between the top of the pot and the soil. This allows you to water it correctly.

Water the plant. You’ll want to work your way all the way around the pot moving slowly with gentle water flow. Keep going until it begins to drain.

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