how trash helps me save on potting soil

recycled plastic for pot bottomEVER BEMOAN HOW MUCH POTTING SOIL it takes to fill a really big pot, and how much it all adds up to at the nursery checkout counter? If I’m going to grow something big, or something in there longterm, I’m happy to fill a container up with fresh, high-quality potting soil. But some plants don’t stay in the pot long enough or have big enough root systems to warrant the wasted medium, and money. I employ a bit of trickery in the form of a false bottom for the pot, and here’s how:

false bottom in big potSimply bundle some used six-packs or nursery pots, or even packing “peanuts,” inside a discarded plastic bag. Secure it closed with a twist-tie, and insert the new plastic “pillow” in the bottom of the pot, preferably on top of a few upside-down plastic 6-packs or small nursery pots, so the plastic bag doesn’t seal the drainage hole shut. Then top up with your medium. You can also just stack a layer or two of upside-down empty small pots or cellpacks on the bottom of the pot.

This is also a great way to “plunge” a young shrub or tree (in its plastic nursery pot, using it for “annual color” before it gets a permanent garden spot in fall) or a houseplant you may wish to use outdoors in a pot bigger than it needs. Just make the pillow platform, balance the potted plant on it, and backfill around with potting soil or even mulch (my preference, for that use). You can even put several houseplants, pots and all, together in a big outdoor container this way for temporary summer duty.

If I still worked where I used to, I’d call this a “good thing.” :)

potting soil and pot

  1. Deanna says:

    Such a good idea! I’ve read to put a plastic pot upside down in the big one and fill with soil, and today as I emptied quite a few plastic 4 inchers, I wished they were bigger. So put them all together silly! Great idear!

  2. Patsy Koester says:

    I, too, used to use the popcorn but since I discard my plants into the woods at the back of my property, the popcorn idea was not the best for me. Now, I collect pinecones in early spring and use those instead. Now, I can just dump the whole thing in the woods to go back to the earth!

  3. liv blumer says:

    To save space in my clay pots I put an upside down plastic pot over the hole and then fill the container with soil. Your method would fill more wasted space. Last summer I also tried putting a plastic supermarket bag with a hole punched in the bottom in a pot that dries out quickly. It was a great help in containing moisture in a hot spot. .

  4. Nancy says:

    Some nurseries also use empty soda cans, as I discovered when I was transplanting. I found myself wondering whether the aluminum could affect the soil (as it affects hydrangeas).

    1. Margaret says:

      Welcome, Nancy. Not sure the chemistry of that! That’s pretty odd that you found cans inside a nursery pot. I have to say I would have been offended that for the price they couldn’t spare the soil. :) See you soon!

    1. Margaret says:

      I always use a bark-based mix (not one that’s mostly peat moss). In the Northeast, the brand I love (and you have to ask for it, but many nurseries use it themselves for potting) is Fafard 52. Again, ask…and be insistent that you wants a coarser, bark-based mix (especially for bigger pots) not a “pro mix” that’s mostly lightweight ingredients.

  5. Dee/reddirtramblings says:

    I definitely do that too. I turn one of the plant pots upside down in my containers. Works every time. Great info Margaret at always. Hope your spring is beautiful.~~Dee

  6. Patsy says:

    What a great idea! I plant my tomatoes and peppers in five gallon buckets and I spend a fortune on soil and they really don’t need all that. I am using your idea this year.

    1. Margaret says:

      @Patsy: I think with big plants like tomatoes, the root systems are big enough that you won’t want to skimp on soil. Ditto even the peppers in the 5-gallon buckets. When you pot up “annuals” like pansies, impatiens, or many herbs etc. in pots, they probably don’t make enough root system to warrant a giant pot filled all the way with soil. So think about the root system of the plant (again, with tomatoes they’re like vines so it wants to get big) when planning what to put a “fake” bottom in or not. Sorry to confuse. :)

  7. Jessica says:

    I often us Styrofoam, helps keep the pots light – and where I have in the past it has been easy for me to come by (it is also a great way to recycle as styrofoam isn’t too biodegradable).

    1. Margaret says:

      Hi, Jessica, and yes, “peanuts” are good (or other styrofoam) but I like to enclose it in discarded plastic bags so the bits don’t get mixed into the soil and impossible to sort out at some future date. But a good reminder: styrofoam is a great choice. See you soon!

  8. Kathy M says:

    Just came in from doing the unending garden chores , went to the computer and checked in on your site as I usually do. Loved your ideas on recycling to help in filling large pots. I have a very large chimney tile and I filled it halfway to the top with crushed soda cans and then added some broken up clay pots then soil. It will be planted with mint and hopefully contained. Should look pretty in the corner of my herb garden. Just finished with this before i came inside so felt I would add this idea to all the others. Now to take a hot bath and hope I can still move in the morning!

  9. patricia says:

    Catching up on my reading and found this good tip. Brings up a question. If I can do this why are these large pots recommended in the first place. Why can’t I just use a smaller pot??
    To Tricia… my favorite, has been for years, is Black Gold!

    1. Margaret says:

      Hi, Patricia, and you can use a smaller pot, yes. Sometimes for aesthetic reasons, though, I like an oversized pot in a grouping, or to contrast against a certain form of plant for “drama” so that’s when this really becomes a useful tactic. For instance, I love growing succulents in big (3-foot-wide) low bowls, but they don’t have deep roots at all.

  10. Nancy says:

    I have a container gardening business and when I fill really large pots I mash empty, half-gallon milk jugs, and add to the bottom of the pot. I don’t want any water sitting in the bottles so after I mash them, I put the cap back on. I also find Fafard to be my favorite growing mix. If the container isn’t huge, I go ahead and fill it with soil; it retains water longer, holds nutrients and allows roots plenty of room.

  11. sonny says:

    I have very large pots and want to grow perrenials in them without filling with topsoil what do you suggest so I don’t have to tear down every year and replace ?

    1. margaret says:

      Hi, Sonny. Not sure what you mean about not using soil? Potting soil (not topsoil) would be required…

  12. Tasha says:

    oh wow. I wish I’d thought of this before I filled two giant pots yesterday with more soil than I thought possible! Thanks so much for the amazing information you share – I’ve learned so much here!

  13. Rae says:

    It’s probably over twenty years that my son bought a new house and had three enormous wooden planters made for the pool deck. The builder made them about four feet deeps. It would have taken a truck load of soil. My son had a business which used those packing peanuts at that time. I used huge bags of them to fill up most of the space. It was the best thing to do.

  14. Victoria Sanchez says:

    I use tons of compost from the top of my compost bin and throw in egg carton type of already recycled card board because it holds the moisture so well.

  15. James Mann says:

    I do find it annoying to use dirt I don’t need and is why I like to stuff things in the bottom of big pots and containers. Things that would normally throw in the garbage.

    We have four huge pine trees that fill our yard with pine cones. They work great.

    I have never put them into bags though. I just toss them in the bottom. I like using things that will end up in the compost bin once I’m done with them.

  16. Barb Kerrick says:

    I’ve been using the fabric potato bags to grow my carrots (I gave up growing them in the garden). Do you think I could fill the bottom with the upside down nursery 6 packs or should I fill the whole thing with soil? It takes a lot of soil, which I have to buy at the nursery. It does start to add up.

  17. natalie says:

    i wondered if you could use the old filters that you use in airconditioners and heaters for space saving ? how about the filters for swamp coolers? they are made of straw i think.

    1. margaret says:

      Hi, Natalie — maybe! I think for me the issue is that I don’t want anything that gets mushy or starts rotting or anything, but maybe those are ok that way. You want really good drainage, so nothing that gets all gloppy and packs down and makes the pot hold water.

  18. Hazel says:

    Can you use a used swap cooler filters to mulch plants? We live in the desert. The concern is leaching salts from the used filters would be bad for plants. We are thinking of using around fruit trees or tomatoes. Any thoughts?

    1. margaret says:

      Hi, Hazel. I would not use anything like that that has been treated (in this case with resins apparently to make it work in the cooler). Why put possible toxins in the garden?

  19. Sue says:

    I save the floral foam from flower arrangments and use in big pots. It holds water and the roots grow right into it. Also packing peanuts but put them in a plastic mesh onion bag. Again, the roots grow through it. I’ve also curb-shopped styrofoam coolers, broken them up and used them in the big pots. My son in Florida cuts up the big floating foam noodles you use in the pool for his pots.

  20. Brigitte says:

    I don’t use styrofoam peanuts — too worried that it would poison the plants. I used to save corks (and get them from friends), but now they are plastic too! I use cans.

  21. Lesley says:

    I have been using plastic bottles or soda cans for years b/c I hate using so much soil in big pots when I don’t need to. Another trick I do, is I take coffee filters and cover the holes of the pot. This allows the water to drain but keeps the dirt from trickling out staining my deck or patio.

  22. Cathy says:

    I brought home from work some packing peanuts that I thought were Styrofoam. Turns out they were some sort of biodegradable material made from potato starch; left quite a mushy mess in the bottom of my pot. Then I found some pot inserts made of plastic at my local nursery. Yes, it was an initial investment but every year I just washed them off and I have them for future use. They look sort of like a dinner plate with about three holes in them for easy lift out.

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