Planters come in a range of shapes and sizes. Whether large or small, planters aren’t always perfectly sized for whatever you’re putting in them.
If you’ve got a planter with a lot of extra space, how do you fill it up?
This is where fillers enter the scene.
Fillers are any material you put at the bottom of a planter, underneath the soil.
Filling can help in 3 ways:
- Decrease the amount of soil you need to fill a planter
- Raise the height of the plants inside
- Give a tall planter more stability
Let’s start with some rapid-fire questions: [Make these into toggle sections]
Should You Put Gravel in the Bottom of a Planter?
No, you shouldn’t use gravel or small rocks at the bottom of planters.
Although it’s often recommended, it’s actually not good for your plants.
The problem with gravel and other small rocks is that they cause the water to pool up closer to the roots. Water can’t pass easily between soil and rocks, so it sits higher up in the pot and doesn’t drain out quickly, potentially leading to root rot and issues with overwatering.
Should You Cover Drainage Holes with Mesh?
Yes, it’s a good idea to cover drainage holes in plant pots with some kind of mesh, if the holes are larger than half an inch in diameter.
Any thin mesh will work. Landscaping fabric can be used to cover the bottom of larger planters.
If you’re using open planters for air pruning, make sure you don’t cover the drainage holes with any material that will block airflow.
Do I Need to Add Filler to a Small Pot?
You probably don’t need to add any filler in the bottom of a small pot. Your plants will have plenty of space, and the soil is unlikely to get compacted under the weight of only a small pot full of soil.
In any situation where you might want to use a filler in a small pot, you can use a small bag full of inorganic materials like packing peanuts, bubble wrap, or bottle caps.
This works well if you’re growing small decorative plants indoors, such as in your office or kitchen.
Can You Fill a Planter with Plastic Bottles?
Yes, plastic bottles can be used as filler for planters. They take up a lot of space without adding a lot of weight or blocking drainage.
Before you use any plastic bottles, wash them out. Keep the bottles empty and put the lids on, so they don’t get crushed.
If your planter is large, you’ll probably need a lot of bottles to make any real dent on plant height.
Can You Put Organic Materials in the Bottom of a Planter?
You can, but it’s not recommended if you’re looking for a long-term planter filler. As a temporary filler for short-term growing (i.e. seasonal growing), solid organic materials like sticks, thick grasses, or dried leaves can work as well as newspaper or cardboard.
The issue with putting organic material in as a filler is that it will gradually break down into the soil. If your filler is meant to push the soil up and raise the plant higher in the planter, you don’t want your filler to break down and turn into compost!
Do You Need to Use Food Safe Materials as Filler?
You only need to worry about food safe filler if you’re planting something edible. If your planter is for flowers or decorative plants only, food safe containers aren’t strictly necessary.
If you regularly rotate out edible plants in all your planters, you may want to stick with only food safe fillers to avoid any issues with toxic chemicals leaching out into the soil.
Some examples of materials that are not food safe are old tires or non-BPA free plastic containers.
Filling for Large or Small Planters
“Planters” is a very broad term. The word refers to basically anything that can hold a plant. That includes built-in planters, large plant pots, or even raised garden bed installations.
No matter what type of planter you have, the filling options are the same.
If you’re filling a large planter and you need to be mindful of the weight, you can use nonbiodegradable materials like these:
- Empty plastic bottles (lids on, full of air)
- Upside down, empty plant pots
- Pieces of Styrofoam, sealed up in plastic bags
- Pool noodles, cut into small pieces
These materials will last for a long time, fill up a lot of space, and won’t be detrimental to your soil, no matter what you’re growing. They also won’t allow water to pool up and grow algae or mold inside the planter.
If you would prefer the planter to be more stable and heavier, you can use other materials such as:
- Bricks, cinder blocks, or large stones
- Broken ceramic pieces
- Thick stumps
Whatever material you use for your planter, it’s good practice to put a piece of mesh or landscaping fabric above it to separate the soil from the filler.
While you can let the soil settle around the filler, it’s unnecessary, especially since it’s not a good environment for any plant roots. The soil will end up wasted and will also make the planter heavier.
DON’T USE:
- Metal or aluminum containers
- Containers with water inside
- Small stones/gravel
- Tires or other rubber items
Final Thoughts
If you’re setting up a planter, using the right type of filler can help you cut down the cost of potting soil, keep your plants sitting in place, and stabilize tall pots.
Make sure you use the right materials as filler and avoid fillers that can ruin your soil or roots. Once you get the filler in place, you can check on it when it’s time your redo your planters and replace materials as necessary.
