Potting soil is not cheap, so whether you are using a large planter as a statement piece for a smaller plant or for a large tree, in most cases you do not need to fill the whole planter with soil. Pot fillers are also a great opportunity to recycle non-biodegradable trash like plastic.
So what should you use to fill the bottom of a large planter?
First, research the plant or ask your local garden center what kind of depth the plant or tree’s roots need. That will give you an idea of how much potting soil you will need. We recommend using a high-quality potting soil and not garden soil as soil outside can be contaminated with weeds and other substances that will not help your plant.
Once you know how much space will be left over depending on the depth of soil you need, you will be able to choose a filler.
Lightweight Filler for Pots
If your large planter is made of clay or another heavy material, chances are you will want to go with a lighter-weight filler. If the planter is being placed in a more permanent spot, this may not be important to you. The lightweight filler is also good for large lightweight planters that you may want to move occasionally.
Options for Lightweight Pot Fillers
- Recycle Plastics
- Plastic Water/Soda Bottles
- Plastic Milk Jugs
- Plastic Grocery Store Bags
- Reuse Packing Materials
- Packing Peanuts (You can put the peanuts in an empty potting soil bag to keep them more secure and better contained if you decided to repot. Also make sure they aren’t the kind that dissolves when wet.)
- Styrofoam Blocks
- Unused Plastic Pots Turned Upside Down
- Recycled Crushed Cans
- Natural Materials
- Wood Chips, Pine Cones, Leaves, and Sticks (These materials will break down over time but work fine for seasonal planters.)
- Recycled Cardboard, Newspaper (Also for short-term use only.)
Heavy Pot Fillers
There are a few reasons you may want to fill your large planter with a heavier filler. Maybe you have a tall lightweight planter that you want to make sure is more sturdy, especially when using it for a tall tree. Maybe your planter will be in a public place where it could get bumped into or stolen. Heavy materials will also work for more permanent installations. Whatever the reason, these are some options for heavy pot fillers.
Options for Heavy Pot Fillers
- Broken Pieces of Ceramic, Brick, etc.
- Large Rocks
- Wood Logs
Make sure the filler materials are sturdy enough so that when you add the soil it will not shift. It is also a good idea to add a piece of landscaping fabric on top of the filler to prevent too much soil from falling through the cracks.
These are just a few ideas, but you can get creative with other fillers, just use whatever you have lying around. Usually, there is no need to go buy a filler, chances are you already have items you can recycle.
Have you used other materials you liked? Let us know in the comments.
Where to find trendy large pots?
Looking for large pots for your plants? These trendy FeatherStone large lightweight planters are available for sale individually (contact email@example.com to order), or if you’re a designer or reseller you can order them wholesale directly from us.
This Post Has 43 Comments
I have a problem with earwigs each spring. I have 10 planter boxes I filled the bottoms with all kinds of suggested items then soil. Now I am wondering if the earwigs are loving all the space and plastic/styrofoam/boxes as living space until they crawl out at night!
What can I use to prevent setting up bug condos for them?
Hi Lee, Earwigs are pretty common garden pests and if you say they return each Spring, I’m not sure if the empty space in your planters is causing more of a problem or not. My only suggestion is to fill in the space between the fillers with soil to give them less room.
I have a large pot that I want a potted plant to go in. I need something to put on the bottom to raise the potted plant up in the big planter. Any ideas of something easy. Internal pot stand thing?
Hi Mindy, I think a good option could be to place an upside-down pot in first, ceramic or plastic, and place the potted plant on top of that.
I found it interesting when you said there are a few reasons why you would choose to use a thicker filler in your big planter. Perhaps you have a tall lightweight planter that you’d like to make more durable, especially if it’ll be used to hold a tall tree. I used to think differently about it not until you explained it briefly and it really got my attention. What you said about landscape design pottery was really interesting to me.
Glad you found the article informative, Jeff!
I have a installation project that will have raised planters with dwarf crape myrtles. Because there’s a parking deck below the weight limits are strict. The general contractor has asked for alternative methods to fill the planters other than soil only. Soil only will jeopardize the weight restrictions. What are alternatives I can use to fill the planters while ensures there’s sufficient soil and within the weight limits.
Hi Alfonzo, Your plant supplier may be able to tell you what root depth is required for that type of plant. Generally, for permanent installations, heavy fillers are more suitable, but for your weight requirement, you can try some of the non-biodegradable lightweight options listed above like plastics and lightweight metals.
I built some raised beds this spring, I’m in the upper midwest (NW Wi.) We had our first frost/freeze of 28deg. Even 26. I buried cleaned and filled with as hot of water as I could handle, hoping for sterilization. We have had 3 consecutive hard freezes and with a sheet over them, the dahlias (24), tomatoes (12) and a beds with 2 packs of state fair zinnia all 7′ or better. Longstory short, I simply dug up the gallon water jugs, emptied them, and filled with warm water each night. 6 total in a 4×6 bed. And the plants are only limp from the sheets laying on them.
Hi, I loved reading all your hints and tips. I have always used Styrofoam…and I use the foam egg cartons broken up and any other foam items, like the trays veggies and fruit come in from the store. I use really large pots and containers for planting my potted garden and using these “Foamies” saves on having to use too much soil. Also, I have lots of old screens and cut a piece of scree to lay on top of the “Foamies.” Hope these tips are useful for someone. — Carolyn M…from Florida
Great tips on some other useful materials, Carolyn. Thank you!
Looking for resources, I found this page and did not need to search further. Thank you. Its a little extra work this time of year, and straying from the exact topic . But maybe applicable. I built and used raised tomatoe beds this year. 3 inches under the surface, I buried repurpose d distilled water gallon jugs verticle, filled with tap water. I take been 28degrees the past 3 nights, I pulled them up and replaced the water with very warm water each night, and reburied them. With a sheet over the tomatoes the loss was very minimal including outer leaves. I still an to vinecropen the last 8 burpees for seed atleast. Now this could be downsized to a 16oz beverage container with (pinholes) 20-30. Enough to seep the amount you need out on any side you have holes. Or leave the cap on to adjust the pressure inside the bottle. Happy trails.
Thank you for all the advice on fillers. I have 3 huge pots and thought I had to fill with potting soil.
can i put small stones in the bottom of my pots before the soil
Yes! You should always put small stones on bottom of all pots, even if theres a drainage hole on the bottom of the pots already! And it’s an absolute must if there isnt a hole! I do with every pot (hole or not! big or small!) You can never go wrong by doing so! With bigger pots, I personally use big & small stones ( or broken ceramic pieces!)but it’s completely up to what you choose!- your already on the right track!
I CUT WOODEN CEDER CIRCULES…PUNCH A FEW HOLES IN THEM FOR THE ROOTS OF MY PLANT..PUT THE CIRCLE IN THE POT…THEN LAY SMALL STONES FOR DRAINAGE…THEN SOIL THEN MY PLANTS…WORKS GREAT AND NOT HEAVY IF I WANT TO MOVE MY PLANTER
Do I need to punch holes in the bottom of the urn and, if so, what keeps the soil from draining out?
Hi John. This depends on a lot of factors, primarily the type of plant, also the environment it’s in, the amount of water the plant needs, and the type of planter. The garden center or wherever you buy your plants would be able to recommend what kind of drainage is best for the plant. In my experience, it is always best to have good drainage, but I am not a plant expert. If this is for an indoor pot and you add the holes, you can use a tray or saucer underneath the pot so no water or dirt drains out onto the floor. Hope this helps!
I’m probably being a space cadet, but I don’t understand how this works. Once you put in all all the milk cartons do you just put the dirt in or do you create a shelf of some kind on top before adding the dirt?
I just put the dirt right on top of the containers and it fell through and filled in all the cracks. You could also put some gardening cloth on top, if the surface is flat enough, to keep the dirt from falling through. You do want to make sure the dirt layer on top of the cartons is deep enough to accommodate the plant’s roots. Hope this helps!
Can I use bubble wrap for my large planter?
Yes u can
Are these plastics/styrofoam suggestions safe for containers that will be planted with vegetables?
I am not sure but maybe food-grade plastics are safe. I know some people do grow vegetables in plastic pots so it should be the same thing. Maybe you could separate the space with a wooden board or piece of garden cloth so the roots and soil don’t touch the plastic? See if this article helps more. https://concordiagreenhouse.com/projects/demonstration-balcony-garden/container-gardening-2/what-plastics-are-safe-to-grow-food-in/#:~:text=Using%20plastic%20containers%20to%20grow,know%20which%20plastics%20to%20use.&text=Make%20sure%20to%20discard%20scratched,grade%2015%2D30%20Litre%20buckets
Hi, thank you for your post! What could i use on the bottom of a large clay pot that would still provide good drainage for planting succulents on top? Thanks!
Hi Jess, I used plastic soda/water bottles because their irregular shape allowed for enough space in between for good drainage. I suppose if you use a mixture of different shaped plastic containers, that would work as well. Hope this helps!
Yes I also need good drainage and I used packing popcorn and the water would come out brown and left the bottom of the pot soiled/stained.. thanks.
Another idea: fill the space with a large, plastic cat litter container, either inverted or with the lid closed. That’s what I’m using in my 2 huge planters!
Yes, good idea! Those containers would fill a lot of space.
Suggestions for a cover to hide to space around the smaller pot?
I haven’t tried this myself, but I bet you could cut a piece of cardboard to fit the gap then sprinkle some dirt over it. You’d just have to remember to try not to get it wet when watering the plant.
I use balled up plastic bags, bubble wrap, etc. you can tape them with packing tape into any shape and size you want to fill in around the inverted pots. Once filled I use a cut to fit piece of landscape fabric to keep the soil on top of it all. It also makes re-potting easier later on.
What is the best filler for a 32″ deep raised bed
Hi Judy, generally the best pot fillers are whatever you have on hand. I like to use plastic jugs or bottles from my recycling. If you’re not worried about weight, you could also use cinderblocks or bricks, or a lighter weight option would be upside-down used plastic plant pots. It really also depends on your preferences, what you have laying around, and how long it needs to last, or how sturdy you need it to be.
Does there need to be a hole in the bottom? Or, will the water eventually evaporate?
Hi Pat, generally it is best for the plant to have good drainage but your garden center or wherever you buy your plant would have the best advice for you. You can use a saucer or tray underneath the pot if you have a hole. If there is no hole, you would have to be careful not to overwater.
When using plastic bottles, cap on or off?
I personally keep them on so the air helps take up more space and they don’t get crushed.
Please advise what filler(s) to use in a new empty planter which 18 feet long, 3 feet broad and 2 feet deep?
Hi Terry, that is a very long planter! It really depends on what you plan to plant in it, but since you have a lot of space to fill, I would suggest using a larger filler like used plastic plant pots you can place upsidedown. Ask your local plant nursery if they have any old ones they need to get rid of. You could fill the cracks in between with any plastic bottles you have in your recycling.
I think that might be a moss pole, meant for the pathos to climb. If it is, it’s your choice of aesthetics whether to remove it or not.
Have a question in the middle of my pothos plant I have a stalk of this brown hay like stuff… Do I eventually remove that from my pot ???
Hi Cheryl, your local garden store would probably know better, but if it’s a dead stem I think you can cut it down to the soil.