If I'm running short of the components of my regular soil mix, or I want to extend that soil for any reason, I will "stretch" it with the one or more of the following:

1) Wood chips and pine needles, aged at least one year in a pile. I get these chips delivered by the dump-truckload, FREE, from a landscaper acquaintance. They are happy to drop it off, esp. if they are close to my home doing a job; prevents them from having to ship it off to a distant location, or worse, PAY to dispose of it. Also makes a good mulch for my garden beds and paths.

2) Pine shavings. I buy it in large blocks from the feed store. May rob some nutrients; though I've never had problems with it.

3) I usually have a bunch of Perlite or Vermiculite lying around. I often add a bunch of that (added benefit of the Perlite; improves drainage, reduces weight. Sometimes it drains TOO FAST, though Al will tell you there's no such thing as drainage that is TOO FAST :)

4) Pea gravel. I have bunch around the landscape that I can spare. Heavy.

That's about it for me.

What is meant by 'packing peanuts'?

Does sams , costco sell a cheap potting mix?

Packing peanuts are the little styrofoam-like things that are used to cushion items being shipped UPS, mail, etc.

I say "styrofoam-like" because some are NOT styrofoam, and would not be stable in soil. Some are made of a starch like material, and will dissolve in water. Put some of the peanuts in water, and if they start to dissolve, don't put them in your soil.

I'll bet you can find packing peanuts in large quantity if you look around; maybe a U-Haul place, or a shipping company like UPS, could help.

Wow, well I have lots of styrofoam ...big ones too, can I use em, will they break over time??! Although its not bio degradable will it cause any other issues?

I think we need to understand what is going to happen before we go adding things.

First, let's define the goal.

If drainage is the goal then you want ingredients of the most uniform particle size you can find. Ingredients of uneven particle size simply find the small particles filling in the spaces between large particles and buh-bye drainage. Rocks, gravel, styrofoam peanuts, vermiculite etc. will not improve drainage at all.

If reducing the volume of potting mix is the goal, first consider using a smaller container. Plants don't care about how deep or wide the mix is, they care about total volume of mix. If a container is too large to fill with planting mix, use a smaller container.

If one already has large containers and does not want to fill them completely with potting mix then put whatever one wishes into the bottom of the container to take up space (as long as it isn't toxic). Make it light or heavy depending on needs.

There is no such thing as 'refreshing' or 'extending' a spent mix (a mix whose particle size has decreased to the point where it holds little air) by using other stuff. If the particle size of the other stuff is larger, the smaller stuff will fill in around it with a few waterings. If the particle size of the other stuff is smaller, it will fill in around the larger particles with a few waterings.

When a mix is spent, it is spent. Nothing will save it other than being put out to pasture in a ground based bed where it can actually serve a good purpose. The only disclaimer is that adding stuff with an irregular shape can add aeration to the mix by virtue of it being harder to fill in around with the smaller particles than something of a smooth shape. Not much comfort though.

Justaguy,

Of course you are correct in your analysis of the effect of adding stuff to the container mix.

I think the original poster simply wanted to get some ideas about "stretching" his mix to save some money. Like you suggested, filling the bottom of the pot with an "extender" is a reasonable approach; I do this all the time with my wood chips. This seems to make the pot lighter and less expensive to fill, effectively turning a large pot into a smaller pot. I realize I am not affecting my drainage or aeration in any way.

By the way, plant roots grow right through this wood chip stuff, out the drainage holes and into the surrounding soil. I actually encourage my plants to do this.

Thanks for the clarification, redneck_grower.
By the way, plant roots grow right through this wood chip stuff, out the drainage holes and into the surrounding soil. I actually encourage my plants to do this

Hey, why not?

Great stuff guys! But the objective of a potting mix like M.gro's is that its light right? In that case is there a cheaper potting mix I can buy in bulk. HD has Scotts Potting mix (2CF for $10).

Also, how about cheap mulch to fill the bottom of a big pot(over a layer of pebbles) will this work to save on Potting mix?

I have some large pots with annuals that don't need the entire depth of the pot.
In order to keep them light AND save on soil, I use chunks of styrofoam (like what electronics come packed in). Over that I put a layer of window screen to keep most of the soil from sinking down to the bottom. Then I add my soil mix.

Quote:" 2) Pine shavings. I buy it in large blocks from the feed store. May rob some nutrients; though I've never had problems with it."

As redneck_grower mentioned , I may go for pine shavings . I think they are cheap,lite, degradable.But why would they "rob" nutrients? In what way?

Because they are a wood product. They are carbon sources which require nitrogen to decompose. In this way they can tie up the N you add while breaking down.

Sapwood shavings/products/chips are largely cellulose and break down quickly, while bark contains lots of lignin, and in conifer bark, suberin. Lignin and suberin are the hydrocarbon chains most resistant to microorganism activity, while cellulose is easily digested. Particle size does affect the equation though. If you opt for using other than conifer bark in the bottom of containers, I suggest you use very large pieces, which reduces the o/a surface area exposed to microorganism activity. Small chunks, chainsaw shavings, and sawdust from sapwood are all going to decompose rapidly, tie up N, and likely cause drainage issues down the road.

Al

The time difference in the decomposition of bark relative to wood, heart or sap, is interesting. I have Douglas fir trees on the ground in my woods for fifty years with the wood crumbly but the bark is still remarkably intact and firm. Al

Thanks, Al ............. which is why we can use conifer bark to such good effect in soils by increasing its presence while decreasing the presence of peat and sapwood products.

Al

I'm a new 'postee'and this is a DUH moment! I soaked 3 half wine barrels through winter. Got rid of residue (Whew), drained and moved to new raised deck location. They've dried out and metal strap is slipping and nice air spaces between staves. Is there a 'practical' way to rehydrate them en situ? As a Master Gardener one would think I'd know better but, alas.... spring brain freeze perhaps?
Thanks for any and all suggestions. This is a wonderful forum. Who is Al?

Al, I should have spent more time on site before asking who your are. I now have....

The staves are probably made of oak (or beech) & should have open vessels since they're longitudinally cut. (If you take a length of oak & blow into the end of a 3" piece [with open vessels evident] while the other end is in water, bubbles will appear in the water as if you were blowing through a straw.) Since the job of these vessels is water transport, setting the barrels in a tub, puddle, kids pool, or other will allow vessels to fill with water & should quickly rehydrate/tighten the staves.

There are at least two Al's here - Tapla and Calistoga. ;o)

Al (one of 'em)

Thanks Al (Tapla),
They're too heavy and unwieldly for me to wrestle around by myself at this point. No kids, no pond. Will continue to think of creative keep soil from leaking out sides ideas. Have your soil recipe too and will be making a batch similar to. Will be putting casters on base for obvious reasons. Have drilled drain holes and will use porus shelf liner to cover holes.
Some crushed aluminum cans to take up some space too. After drinking whatever they contain!

Line the inside of the container with a single layer of newspaper. Fill the container with moist soil & it will swell tight in a few days.

Al

Thanks Al,
Perfect timing as we're spoze to get rain over next couple of days. What do you think of the sluminum cans at bottom of barrell as opposed to stryofoam. I'm also planning on using "diapers" - at least the innards, to help with water retention. Not sure if there would be any leaching out of bad stuff but if they work for babies they should work in containers. Was a suggestion at one of our MG workshops on Container gardening.

I think they (cans) will hold water & get all funky. Why not use soda bottles with the caps on, or partially filled with water & some kind of common antibacteriostat (bleach, ammonia, rubbing alcohol)?

I'm not sure I would use the diaper trick, except as a last resort if you're sure you really need the extra extension of between-watering intervals, but of course, it's up to you.

Good luck, no matter what your course. ;o)

Al

Last year I used left over Easter Grass (the plasticy type) from my kids baskets to take up space in the bottom of a few big pots. First lined bottom with a layer of newspaper to cover the hole then pushed down a bunch of Easter Grass and then another layer of newspaper. So far so good... I had the one pot in the house over the winter and hasn't shrunk down at all. Worked good I scooped it up out the baskets again this year and even bought a couple extra bags on clearance in case I need it.

Good ole plastic Easter grass. I am still finding that stuff in my garden from the one time I used the stuff in my grandkids' Easter baskets back when they were two and four years old hunting eggs in the back yard. They are now 16 and 18. So Bluebird, when I read your post, I shuddered. LOL

I just read this morning in a little booklet called "No Toil Power Soil" that you can turn your large containers into a lasagna type garden. "Start by covering the drainage holes with several thin layers of wet newspaper. In very large pots, you can fill the bottom with empty cans turned UPSIDE DOWN...next add a 2-inch layer of compost, then a layer of potting soil, then more compost, then more potting soil yada, yada, yada. Pull back the layers and pop in your plants. After planting, cover the soil with a mulch to preserve moisture. Later in the season you can fertilize with compost tea or liquid fertilizer of some sort.

I have yet to try that in particular, but it sounds like a very good idea. In my big containers, I use large chunks of landscaping mulch in the bottom third of the pot. It has always worked for me. The roots go down into that mulch and seem to like it. Hope this works for you.

Sorry to say so, Aulani, but I think that that both the stratification and the combination of ingredients will offer a difficult set of problems to overcome before you could expect reasonable vitality from (a huge % of) your plants. We know that stratification is a problem because of its propensity to cause 'perching' of water high in the container, and high levels of compaction/water retention is already built into the combination of potting soil/compost. It might be marginally usable in SWCs, but I think it would be a train wreck in conventional containers.

I wish the author of the booklet would make him/herself available here to discuss the idea. ;o)

Al