It depends on the quality of the potting soil you are starting with. If a high quality, durable custom mix like the 5-1-1 or gritty mix, you may not even need to refresh annually. I typically go a couple of seasons before the need arises.

But if you are using a very finely textured commercial mix like Miracle Gro, you are lucky you made it through even a single growing season and I would replace - not refresh. It compresses and collapses and refreshing with a portion of new soil or even adding a high percentage of perlite cannot adequately correct these deficiencies.

I use the 5-1-1 for virtually all my containers and then refresh with 30-50% new soil mix when the time comes. The second 'refresh' is typically a 'replace' :-)

btw, creating your own custom mix - like the 5-1-1 - generally turns out to be far more inexpensive than purchasing an inferior commercial bagged mix. And produces much better results!!

What is 511?

I see! I just bought some organic potting mix from HD (Kellogg Premium Mix for Outdoor Containers). Will I be able to incorporate this into the mix to make use of it? I am sure it has some peat in it because it says it has water retention properties.

Also...I don't have sifted bark fines and my gardening expenses are way above limit at this point. However, I have large pile of ground bark left over from a huge tree that was cut last year. Can I use some of that instead of buying more stuff? I could use some savings. :)

Also, will this work well for a container rose too? Is this soil good for any potted plants?

511 is a mix you make yourself, with the ratios of 5-1-1. I think it's fine bark, pearlite, and peat moss. I don't make my own, so I could be wrong there.

I get pro-mix by the 2 cu ft bale. Depends on who has a good sale, but I often find them around 13-15 bucks a bale. I tend to use around 3 cu ft a year for starting seedlings and early potting ups. I grow a lot of peppers in under 5 gal pots, a couple tomatoes in 20 gal round pots, and an assortment of vining flowers and veggies in a handful of 20 gal square pots. And usually have a couple dozen perennials growing out in gallon pots and a handful of 20 gal square pots.

I also have a few compost piles and leaf mold patches. I start a lot of seed with the pro-mix, and pot up a couple times on the peppers and tomatoes. The assortment boxes are usually direct sow kinds of seeds that vine up trellises, with some other growing out stuff. This year I get to harvest candy lilies out of a couple big pots that are finally ready to plant out in the yard.

Since those lilies have been growing a couple years now, after I get them out there will be some dirt in the bottom. I'll break that up, dump a couple pots of last years pepper pots in, and a goodly amount of compost and leaf mold. And those pots will be ready to go for a couple years again without needing much more than a bit of compost top dressing.

The larger tomato pots will get turned with some compost and leaf mold too. I just gave them a big refresh last year, so they don't need a lot.

With most of the rest of the smaller pots, they get tipped and mixed with compost to repot up those seedlings that are already in a goodly amount of fresh dirt to start.

After that I often have some dirt leftover- I use this for the perennial containers. I add in a couple shovels of sandy loam from out back, an extra dose of leaf mold. Sometimes I got a bale or two of blown straw sitting, and I like to dig in some straw into the larger bins on occasion. Works really well when I'm growing out irises or lilies.

Kellogg's is better than most but still not great. As to your tree remains, it depends on what kind of tree it was and just how much of the ground up stuff is actual bark and not the wood. But bark fines are available for pretty cheap anyway........usually less than $5 for a 2 cf bag.

And yes, the 5-1-1 mix can be used for just about any containerized plant other than cacti or succulents. I use it for all my containers both indoor and out.....with the exception of the C&S.

Do they carry sifted bark fines at big box stores like Home Depot? Is this the precise name I am supposed to ask about or will I find it under different names too? Like ground bark, etc?

Also, can I incorporate a bit of this Kellog soil I just bought so I can put it to some kind of use? Or should I use that in the yard when I amend the soil at the base of plants and mix it up with some cow stuff?

If you could provide a link to a good product, I would greatly appreciate it.

I want to make sure my container rose will have a good start with just the right kind of potting soil.

Also, while I am sure beesneeds has success with her container plantings, be advised that compost, leaf mold and most of all, plain garden soil are NOT recommended for containers.

Read that thread I linked to for a great explanation of why this is so :-)

Yes, it often sold at places like HD or Lowe's. Or Ace Hardware or Agway if there are any of those near you. Depending on supplier, it could be labeled differently: fine bark mulch, pine bark fines, soil conditioner. Even orchid bark works. You just want to make sure the texture is rounded, not shredded, and that they are approximately 3/8" to 1/2" in size to minimize wastage.

And you can use your current potting soil as the peat based portion of the mix. It is also okay to go off a bit in your proportions, using only 3 parts of the bark or 2 parts of the peat.

Gardengal,

This is very, very helpful! I did a bit more reading on the forum and I think I am getting it.

I had seen soil conditoner at HD before and was even wondering what is it that people do with THAT?

Am I correct that gardeners use this custom mix mainly because the regular potting soil from the store is too heavy and becomes compacted over time? Also, is it more expensive to use straight-from -the-bag potting soil than to mix your own? I am not sure custom mixing is any less expensive (plus the extra labotr involved) - but if it does a better job for the plant, it's worth it.

Mixing your own IS cheaper...and by quite a wide margin if you do a lot of container gardening :-) And results in a far better end product!

And a custom mix like the 5-1-1 is superior to a bagged mix because it is more durable and with better texture so it does not collapse and compact with time and frequent watering but maintains good aeration and fast drainage longer with a lower PWT.

It is true that how I regularly add in new stuff and the stuff I use isn't conventional for container growing. But it does work great for the kind of container gardening I do. Stuff thrives and often I get earthworms happy in the pots to boot. It's also sometimes more labor intensive that mixing a more proper 511 or gritty mix can be. But I find this way satisfying as well.

Gardengal is absolutely correct in that a better mix with bark fines is, well.. better. For a lot of container applications. Kind of depends on what kind of gardening you are doing with your containers to an extent. And the kind of container gardening you do.

One more question: if virtually all of the potting soil in commercial bags is less than ideal, why is it that stores don't sell the kind gardeners mix? With bark fines, in the right proportion, etc. Especially if it is cheaper...I am not quite getting the industry angle of this. Why is it the industry insists on selling the heavy potting soil?

Because they - soil vendors - are not necessarily au courant about what constitutes a "good" potting soil. It has only been fairly recently that better wholesale growers have been using a bark-based soil for their containerized plants. And because the vendors also have a lot invested their current processes and procedures. And while inexpensive to make, just like their current potting mixes are, the convenience of having it already done for you will always command a higher price than if you were to do it yourself :-)

That makes sense. But I thought the potting soils vendors sell also involve some kind of mixing. It is not just pure soil, is it? thought those too include some moss, perlite and other ingredients. You'd think they would adapt and update their mixes, if more recent growing experience supports the use of bark.

I guess I'll have more to buy - but they will all be used up in the end.

While I am at it, I thought I'd get some lime too as some recipes seem to think it's worth including.

This was very useful information for which I thank you very much! I look forward to seeing a difference this summer.

There isn't - or shouldn't be - any "pure soil" in any potting/container mix. It is also referred to "soil-less" mix, as 95% of commercial mixes are just peat or coir, perlite or pumice or vermiculite and various other, usually non-essential, additives. No actual 'dirt' of any kind :-)

And how easily these folks would or could upgrade their product depends on a lot of variables....like brand recognition (MG would get all kinds of flack if they did a radical change as they have a devoted following, even if it is one of the worst potting soils you can buy!). And when you purchase peat or coir or perlite, etc. by the multiple tons at a time, you've likely got a huge backstock of supplies available. And there is the need to source the other necessary ingredients to create a better quality mix. The bark fines tend to be a limiting factor.

Kellogg's is about as adapted as you will get for a commercial bagged mix :-) There IS a lot of bark in their mixes but not to the best proportions and they also add a bunch of stuff that is extraneous as well.

Unless you are growing acid lovers, you do need to add the lime to the 5-1-1 to offset a low pH created by the peat and the bark.

I bought an 11 pound block of coir, anticipating mixing my first batch of homemade potting mx. The recipe I am looking at includes perlite and compost. We'll see how it goes. I also save the potting soil that comes in newly purchased plants for re-use--that's how frugal I am and that's how many really large containers I have to fill. I save the dead chrysanthemums in pots over the winter to re-use the mix in the spring, before I pitch the dead Chrysanthemums into the woods. One might argue that there could be pests and disease in old mixes, but I once bought a pot of commercial mix and everything died in the pots I used it in, so I guess you are always taking a chance. I only refresh on top of my containers, maybe putting in all brand new mix every four or five years.