Hi Dave,
I too am assuming the redwood chips are used for drainage..
There are two types of house plant potting soil sold here in IL..Most brand name types contains quite a bit of peat. Off-brands are a richer, black, heavy soil.
Depending which soil I buy, I add sand, (Builder's Sand not beach) bought at Home Depot,) and Perlite..Well-draining soil is really important when most growing plants.
If the soil is heavy I also add a couple handfuls of peat.
I'm not sure if peat retains water or not..it's become a mystery..You would think so, but I've noticed most plants that are shipped to nurseries are potted in a peat-base mix. (I'm talking green house nurseries) Yet, many of these nurseries use machinery that spray a fine mist of water every 30 mins to 1 hour..I've discussed this very topic with owners of local green houses, and haven't come to any definate conclusion.
Therefore, when I mix soil for citrus, (I mix my own mediums) if I'm using the rich, black soil, I'll throw in a a couple handfuls of peat..
So, for heavy soils: eg..8 cups black soil. 3-4 cups sand. 2-3 cups Perlite. 1-2 handfuls Peat.
Peat-based soils: eg. 8 cups soil. 3-4 cups sand. 2-3 cups Perlite.
I also throw in a few handfuls of charcoal.
Whatever you decide to use, when mixing, do so thoroughly..You want an even blend..As long as your soil is well-draining, you've got it licked..Toni

Their recommendation of the bark chips (be SURE that you use bark and not the inner wood) is to facilitate AERATION. The mixes that are the easiest to grow healthy plants in are very porous and coarse textured. And trust me....there is no 'best' mixture! Just remember that you want to build a medium that will always be able to provide oxygen to those roots...thus aim for coarse-textured ingredients.

Your typical house plant mix contains mostly peat, some perlite and vermiculite. Not enough perlite to do much good, though. Peat is a very good ingredient to start with, as long as it is not sedge peat (black dirt) which creates a muddy and mucky potting mix. At nearly any big box store you can find bark fines, which consist of particles about as large as a finger nail and smaller. (No need to hunt for redwood bark.) PERFECT for amending your potting soil! Also, add a plentiful portion of coarse perlite for added porosity.

Sand, unless the particles are about the size of a BB, can end up compacting into the large pore spaces, which is the opposite of what you should be aiming for.

Start out by mixing one/third each bark fines, perlite, and potting mix (or so...no need to be exact). I think that you'll like the results. You will be able to water thoroughly every time, with no fear of soggy soil and root rot. Thorough watering flushes out soluble salt build up from fertilizers, gets rid of carbon dioxide build up in the soil, while filling those nice large pore spaces with fresh, oxygenated water and air.

I used to use the combination of materials that I've recommended to you with great success. You will be able to readily locate the ingredients and won't spend a lot of money on them. It's not what I use these days, but I feel good about suggesting it to anyone.

Let me know, won't you, if you need any further help?

Suzanne..What's Steer?
I've heard of Black Gold, maybe it's sold at Home Depot..? Is that where you buy it?
Also, you add Osmacote when repotting..how much do you use, and do you mix your soils together then add the osmacote inside??? Oh one more thing..lol..which osmacote do you use? I've never seen osmacote for citrus..only house plants, veggies, and I believe, flowering plants..Thanks, Toni
PS..since you're in WA, can you leave citrus outside yr round?? If not, how in the world do you lug 32 gallon tubs in and out?? LOL..

Toni....it's me remember?????????? I have (2)greenhouses and in my larger one is all citrus dwarfs.I just start dumping into a wheelbarrow to mix all together.Osmacote I mix in as well with all of the above ingredients..about 2 cups.And Toni,,,it would be bagged & aged steermanure.Home Depot shold carry Black Gold.I buy the large bags,all my citrus is planted in this same mix.I have a Bearess lime,Key Lime,Indio Mandarine Quat,Cara Cara Orange,Honey Murcott Tangerine,Satsuma,Rio Red Grapefruit,Lisbon Lemon,Meyer Lemon,Wash.Navel Orange,Dancy Tangerine and all put out profusely!Never have to buy lemons or limes....I think the clue to citrus is NOT to fret to much over them,and the main thing is to FEED THEM,not just fertilize them!Black Gold has a good amount of sand & peat moss.I have not found a better soil,I use this for everything in pots.I even have (2) Columnar apple trees potted thriving in this mix.Of course they only get 5 feet tall,but they are thriving! Also when I water my citrus,I also spray them really good,,,for they love showers! Suzanne

With this type of soil put into containers, do you ever have a watering concern? Living here in Massachusetts where the days are short, and I cannot stick my trees outside, until the spring, would this type of soil stay to wet for too long and cause root rot problems?
Is it well draining? How long can you grow a tree in the same pot before the soil breaks down and compacts? Is this soil to heavy for some like me up here where plants are kept inside for about 6 mounths? One more question..Lol
When you say feed them, what do you mean and feed them with what? I thought Citrus and Advacato and vine food was an organic fertilzer. I thought fertilizing them was feeding them. What can you feed them that wont make your soil even heavier than it already sounds? Citrus may love this soil and your soil sounds appetizing to your trees, but does it work for those of us in cold climates? Keeping our trees indoors half a year at a time?
I would love to know. Thanks suzanesks!!!:-)

Mike, the very successful and knowledgable growers above are giving good advice. Here is my 2 cents:

I too am in z6 Massachusetts, which means the outdoor growing season for potted plants is maybe, barely 6 months. Rest of the time is indoors, and no, I have no greenhouse.

For woody plantings in containers, the most important factors to me are drainage/aeration of the soil mix, and its long-term stability. For the latter, inorganic components offer a big advantage, as they don't break down or lose their air-holding capabilites over time. Thus, for citrus, I am growing in 50% Turface (a baked clay granule originally developed for baseball fields), 33% pine bark mulch, and 16% perlite. This coarse mix (I use it in plastic and clay pots) has tremendous water-holding capacity through the Turface yet is reliably well-drained and aerated. I generally water this mix about every two weeks in the winter, indoors, and up to daily during the hottest part of the summer. There is very little nutrition in the mix, so I incorporate a controlled-release fert in the mix and water with liquid fertilizer as well.

(By the way, credit for this mix goes to Al (tapla) over in the Containers forum - a generous and experienced grower.)

Hi tee....

Believe it , but I am using the same mix that Al recommends, in some of my pots, I havn't been growing long enough in it though to see good results with a few of my trees. But I hope I do. I like the mix alot. I am still trying to get use to the watering thing. Because it can be bone dry, enough to kill your plant, and the mix still feels heavy. But Al told me how to make sure for moisture. Just takes some practice. I was curious as to wondering if suzanne was having water issues and drainage issues with her mix and where does she live that she uses so much of what others are suggesting that should not be added to soiless mixes. Hum
But my main interest is, what the heck is meant by
"thing is to FEED THEM,not just fertilize them".
Isn't fertilizing them feeding them? And when you feed them with organic such as Avacado and citrus natural powder, will it not be rendered useless in a soiless mix with no microbes? Seems like she is using lots of ingredients that could easily compact over time, and not be useful in a soiless mix. How is this so that she is having sucess with this type of soil? Maybe she lives in a southern climate and not north such as us where the sun dries out her pots very fast?.:-)

Mike -

A soilless mix will nevertheless harbor quite a range of microflora, as long as their basic requirements: water, air, and some nutrition, are supplied. Soilless doesn't mean sterile! Most microbes will live and thrive in a leaner environment than will sustain your tree.

I use inorganic fertilizers because I like the predictable dosages I can achieve, but others prefer organics. Each to his or her own; there are many paths to success, and success is a composite woven from each grower's climate, conditions, habits, and available time, etc. Many time the tips and advice from other growers can be translated directly to your conditions, sometimes it can't. The flipside to the wealth of expertise on these forums is the wide range of conditions people are coming from. You have to be willing to evaluate where (the excellent!) advice is coming from and whether it applies to your situation.

tee530, VERY well said!

I remember black gold or was it black magic? I can't find that and I just can't find any potting mix that is up to par. Super soil used to be good, but now it's terrible. Miracle grow kept the soil too wet. I still want to know what one would use to pot a lemon tree, if they wanted to buy a brand name in a bag. Mixing your own is a problem when I can't find all the things I will need to make the gritty mix.

HI suzannesks(z 7 WA.), I tried your recommended mix recently when repotting my citrus, but am having issues with drainage. When watering my citrus, the water takes forever to soak in, and does not drain out thoroughly, and seems very waterlogged. Just curious if the mix you use seems to hold in the water, or if I maybe added in something wrong.

Tropical, I thought the same thing because some of the ingredients of the gritty mix were hard to find. However, the ingredients for the 5-1-1 mix are very easy to come by and that mix works well. I don't think you will find a bag of mix that will work nearly as well.

Joel not sure if you aware of the fact that this thread ended in 2012, almost 4 years ago. I hope Suzan is still around. I am glad back then I was using well aerated mixes and still do)

I think about Rhizo often. I think I will send her a note)

Lol Mike, I had no idea the thread was so old ☺️