I avoid any drainage material in favor of a uniform soil - top to bottom, but that's another discussion.

I will say that garden or topsoil in a container will be counter-productive & increase water retention while destroying aeration. Newspaper will quickly compact to a soggy mess & promote soil organisms that thrive in oxygen-starved conditions.

What about using an upended smaller container in the bottom of the larger, or just use a smaller container?

Al

I've seen the styrofoam peanuts mentioned, and plastic water or soda bottles.

I have had great luck filling the bottoms with pine bark nugget mulch--- it's light weight,natural, easy to find, and inexpensive. One caution though anything you use will make the pots dry out quicker as water will sieve on through-- Good Luck

I see debbie's point. I,too, plant several very large containers full of fast growing annuals. They simply don't need the entire soil volume, it seems. I've always filled the bottom of those containers with the packing peanuts, and the plants seem to be happy.

Since my potting medium is extremely porous, and so are those pp, extra watering is required at the beginning of the growing season. But at the end of the season, when I am cleaning out and storing those pots, plant roots have completely wrapped around every pp...something that I've thought interesting. That layer of styrofoam comes out like an integrated whole, not individual peanuts. LOTs and LOTs of nice healthy roots.

By the way, be observant if you use the pp. Styrofoam only, not the corn starch ones that dissolve in water.

I have used smaller plastic containers (the ones small plants come in from the nursery), they seem to do well

Fill the container with those empty plastic easter eggs.

Last year I used many, many plastic water bottles in my giant pots. My pots looked fantastic all summer and I plan to use them again. The potting medium I buy for my containers is about $20 per bag - way to costly to fill up large containers when you don't need to.

Maggie- Thanks for that tip; I hang my hat on the Winter Sowing forum, and we've found that the smaller water bottles are too small for WS-ing, but this is a good use for them!

To answer the OP's question, I've also heard you can use aluminum cans.

I had some small pails that I planted leftover Impatiens in last year and I was low on potting soil so I put 2 glass Coke bottles,(the smallest ones) and layed on their sides in the bottom of each pail.They took up one third of the pail.These were the best of all my containers all summer long.The plants grew large and bushy,just beautiful.

I like the plastic bottle idea, I think I'll try it this year. Be wary of what you use, though. Last year, I used crushed pop cans, and when it came time to dump out pots, I had a tangled mess of roots, cans, and soil. It's easier just to recycle them.

I use uncrushed soda pop cans - works great and lightweight.

Deb

I've tried the styro peanuts, and do not like having to deal with them when it is time to re-pot. I often use a variety of organic materials such as leaves, twigs that are bulky and light. By the time I am ready to re-pot they are composted or at least it is okay to put them in the garden as-is.

Try small stones, that'll work.

I am going to try using old 1 and 3 gallon plastic pots (inverted) from other nursery plants. They cost nothing, are very lightweight and the different sizes can fill amost any size space. You can get these free at most nurseries. Then use plastic water or pop bottles to fill in the space around the rest.

Grancru

If you have them around, pine cones work really well, they weigh next to nothing.

I too also use plastic water bottles, soda bottles, and plastic milk containers and have for about 15+ years. Just make sure that these are the type of plastic bottles with the screw-on tops.

I make all my own compost (of which there's never enough) and to save on buying bags of potting soil, I mix regular garden soil with rough compost. Sometimes going as much as half soil and half rough compost. The compost continues to break down in the soil and feed it and the plants. You wouldn't believe the worms that I have in my large planters.

If you use things like cans or plastic bottles, put a good healthy layer in and shake (if it isn't too large of a container or planter) and then water it well. This will help to settle the soil/compost mixture around whatever you have on the bottom. I then water again after I have it filled with the soil mixture and let it sit for several days before I plant in it. This helps the soil to settle. If you find that it's still too low for your liking, then just add more.

Hope this helps to give you some ideas.

Jenna

Absolutely don't use garden soil--I speak from sad experience. Don't use stones either, as you want to be able to lug pots around. Everything else more or less works, in my experience, though it's true that styrofoam peanuts can be messy when repotting. Al argues against anything, in favor of giving plants all possible room for roots, and that has certainly influenced me against plastic bottles (though I still have a hidden cache of them to use for containers with annuals).

Don't the lighter containers blow over? I fill my containers with potting mix. Period. If it's a really big container I won't be able to wrestle into place, I put the container where I want it, THEN fill.

Lisa

I put packing peanuts in a mesh bag (like what onions come in from the grocery) before putting them in the pot. No more sorting peanuts out of soil, as the wind is blowing them into your neighbor's yard :) I like to do this with pinecones too, since they'll last several seasons.

WOW - a lot of good ideas here. I came here to ask this very question or at least search for an answer. I am doing a large galvanized tub 2 sq foot and about 2 ft deep and wanted to see if my idea of using uncrushed soda cans would be a good idea but the soda bottles seems like a good idea too. Gonna think a little bit more about exactly what method I will use but glad to see I wasn't TOOOOOOO far offbase. I have a bunch of wildflower seed and wanted it in a more controlled enviroment rather than just sowing it in the ground and then questioning what was weed or what was seed...

Lynne

hollyhockdoll,
What a very good idea!Never occured to me.

For the last several years, when planting my annuals in large pots, I simply take the plants out of the plastic containers they come in and toss those in the bottom of the pots. Makes the pots much more light-weight and easier to move if necessary, helps with drainage, saves on potting mix, and saves the landfills from all my cast-off plastic container thingies.

I thought it was interesting to note that I have seen some roots go right through packing peanuts, i.e. spearing them. While I may not be wild about them being integrated into the plant like that, it doesn't seem to stunt them and makes good use of an otherwise environmentally-unfriendly product.

I have used 2 liter bottles and smaller water bottles. Smaller (like 16 oz) Gatorade and such soda bottles, too.

Please explain why I shouldn't use something like M.G on the top and a cheaper potting mix with perlite added on the bottom. I really would prefer soil in my pots instead of other stuff (sorry).

Really need to know,
Thanks
Karen

Alex, plastic peanuts do work as a great surface for the roots to interface with and they will also grow into them. There have been quite a few studies done on this. Certainly not as good as a terrific, coarse textured potting mix, but as far as providing a good environment for vast root development....pretty darned good.

Karen, you would be better of mixing the cheap stuff (a soilless mix) with whatever name brand you use, rather than creating an artificial layering between two different planting mediums. It is possible, I would presume, that drainage could be impeded if the bottom layer is finer textured than the top. If your entire substrate is homogeneous, that backup of water is less likely to happen.

Karen - Dorie is right, in that different soils in the same container will create watering problems and a homogeneous mix is best. A finer soil on the bottom will create an unnecessarily high level of saturated water there & if you use a fine layer atop a coarse layer, the water "perches" in the fine soil above and doesn't drain into the soil below.

Many times, even marginal quality potting soils can be vastly improved by the addition of a fairly substantial volume of pine bark and some perlite.

Al

I use lava rock, it is lightweight and takes up alot of room, plus I like the rough edges, such that it won't "pack" down.

But I really like the plastic easter egg suggestion! I hate those stupid things--I have had some taking up space in my house for several years because they are not recyclable and I couldn't bring myself to just throw them away--so un-ecofriendly! Now I know just what to do with them!!

Thanks for the reminders- a couple variations would be to put the peanuts in a ziplock bag which would allow you to reuse them. Could mess with drainage but the basic idea worked for me.
Also, after I read your posts, I found a couple gallon pots to put upside down in my containers but the holes on the bottom of the pots would allow soil to fall in which reminded me of another tip I learned. Cover the holes with a coffee filter which is degradable over time but prevents soil from falling in. I also use the filters to cover holes in any pots or containers I use.

I know this is an old thread but just thought I'd throw my two cents in, in case someone comes across it. I have used styrofoam pieces and peanuts to take up space and if you put them in a mesh bag, like the kind onions come in, it's easy clean up when you empty the pot and you're not sifting through soil looking for styrofoam.

I am a novice, but after reading this and a few other threads I've decided to try (bottom to top) several bricks on the bottom of my tall planter pot for stability, followed by milk jugs of water, then landscaping cloth, then potting mix.

Big mistake ...........

Yeah, my wife said the same thing... what’s your advice?

I always filled my large planters with potting mix. The one time I put empty milk jugs in the bottom to save on potting mix and weight, my plants did not do well that summer. Same plants as other years. I’m guessing it was a drainage problem, though I can’t rule out some other unknown change in conditions that year.

There is nothing wrong with using ballast in the bottom of your pots if you use it correctly. It can eliminate almost 100% of the potential a soil has to hold excess water. Used incorrectly, it serves only to reduce the amount of soil available for root colonization, while at the same time it caused water to perch in the soil above the ballast/drainage material.

Ideally, you would fill the entire pot with a soil that holds no or nearly no excess (perched) water. If you can't do that, then ballast and/or wicks are the best bet.

Al

I had wondered about spray, expanding foam. It would fill the container, be light weight, could be punctured for drainage. My concern might be chemicals that would harm the plants or leach into the surrounding landscape. Thoughts?

Put a covered Styrofoam or plastic cup filled with water (for the weight) directly over the drain hole, then fill with foam around the cup. Remove the lid from the cup, cut the cup off even with or below the fill material, break out the bottom of the cup (for drainage), and allow the cup to fill with soil when you add soil to the pot. This would be a very effective way of reducing the amount of perched water a soil can hold. If the foam depth is equal to or greater than the ht of the PWT the soil supports, your perched water volume should be 0.

Using this method would be effective in any case where the material used as a "drainage layer" would normally be counterproductive because it caused water to perch above the layer.

Al

Al, this is 3 years later, but thank you! I have most of my plants in the 1-1-1 or 5-1-1 mix, but I have a few huge, beautiful pots, and screening to fill them seems like a daunting task. I bought expanding spray foam and was looking for a way to impliment this idea without creating unforseen problems. I always appreciate your advice. Over the years you've given my love of plants a solid foundation of knowledge and understanding :)

Thanks for the kind words.

The best way to decrease the amount of medium it takes to fill a pot; and, to limit the volume of excess/ perched water a planting can hold is by using ballast.

Note (fig D) how much less excess water a planting can hold when using an overturned pot as ballast.

The figure on the right below illustrates how you can use brick or hollow plastic blocks as ballast. If you were to turn the bricks on edge and add 2 more, you would almost entirely eliminate this planting's ability to hold excess/ perched water. Make note though, that there must be at least 1 continuous/ unbroken soil column from the top of the soil column to the pot bottom. If the bricks were turned 90* and 2 more added such that the bricks or other material filled the pot bottom so that there was a 2"x2" gap between the bricks to provide the unbroken soil column I mentioned, the only grow medium in the entire planting capable of holding perched water would be the medium in the 2 x 2 space between the bricks.

Al