The more small-growing ones should work out as long as the potting soil holds up. Some of these like the Nootka cypresses and the Serbian spruces may be too large-growing to last 10 years.

If the pots have tall shapes use shorter plants, even weeping if the pots are tall enough. If instead more broad for their height then suitable for tall plants.

of those i know.... which is all but a few ... i would guess that only the following will remain compact enough for a pot

Pinus parviflora 'Ogon Janome'
Abies koreana 'Silver Show' or 'Silberlocke'

the others are aggressive enough to get too large in the time frame .. either for the pot... or to blow over in the wind ...

no comment on these:
Abies koreana 'Blauer Pfiff'
Thuja occidentalis 'Malonyana Aurea'

for small, slow blues think:
Picea pungens 'St. Mary's Broom'
Abies lasiocarpa [var. arizonica] 'Compacta' 4 IN BL

as noted... something like green arrow ... will get to tall .. and cause the pot to fall over.. IMHO ....

and finally ... anything will go in the pot.. if you learn some basic bonsai root pruning .... of which i am no expert ... but basically.. if you un-pot and cut all the roots every year.. you can stunt the annual growth rate .... that is really the basis of bonsai ... that plus some fancy dramatic pruning above ....

as always.. good luck ...

ken

PS:.. the key .. look for annual growth rates in the 1 to 3 inch per year category .... and if you start with a one foot plant .... in 12 years ... it will be about 4 foot .... is my math right??? .. lol ... a lot of those you list have 6 to 12 inch predicted annual growth ... if not more ....

Any container that holds 4.5cf of soil is not going to blow over in the wind.....unless we get a hurricane up here :-) They are just too heavy.

Large trees are grown in containers all the time. Many rooftop gardens in downtown Seattle feature them. I'd choose any of the slower growing selections. Container culture offers a natural dwarfing situation, slowing growth even further, but 10 years is a long time without some sort of root/repotting attention. And the issue of the potting soil is a valid one - you will want a container soil that holds its texture well, so long on the slow to decompose organics (bark fines, coir, etc.) and the mineral component that provides good drainage and go easy on the compost. But even a very stable, high quality container soil will need to be refreshed after about 5 years.

You might want to pose a question on the Container Gardening forum regarding a potting soil recipe that will provide the best characteristics. Al (tapla) on that forum is an excellent resource and is considered an authority on long-term container culture.

I grow a lot of conifers (in fact, most of my collection) in containers long-term but most are dwarf or very slow growing forms and in much smaller containers than you propose. I repot and root prune about every 3 years.

Here is Al's Gritty Mix recipe. I've put this mix together and it's VERY heavy...those pots wouldn't be going anywhere!

For long term (especially woody) plantings and houseplants, I use a soil that is extremely durable and structurally sound. The basic mix is equal parts of pine bark, Turface, and crushed granite.

1 part uncomposted pine or fir bark
1 part Turface
1 part crushed granite
1 Tbsp gypsum per gallon of soil
CRF (if desired)
Source of micro-nutrients or use a fertilizer that contains all essentials
I use 1/8 -1/4 tsp Epsom salts per gallon of fertilizer solution when I fertilize (check your fertilizer - if it is soluble, it is probably it does not contain Ca or Mg. Thanks Al!

The post linked to below contains links to most of his posts...huh. He has made me completely re-think my potting strategies, especially not using short containers to save on potting media costs when taller pots provide much better drainage.

Barbara

Here is a link that might be useful: Al's container soils thread

Will,

If your after effect I would plant any of the above in the large containers you have.

When they have reach a point where they are out growing the pot remove and plant. Then start the process all over again.

Simple enough.

Dave

Wow thanks for all the responses. I don't think weight will be an issue. First of all, these pots will be on my backyard patio, very well protected from the wind by large and dense trees all around it. Also, the pots must weigh about 90 pounds each now after I put the potting mix in. I could even line the bottom with bricks to make it heavier.

Naturally Ken, I could plant a smaller plant in them, a dwarf or large 'mini', but the idea was to have a semi-formal entryway to the backyard garden, with two tall narrow 'pillars' flanking the entry path. I'd really like to do Picea omorika 'Bruns' or 'Pendula Bruns', I just wonder how happy the roots would be when the tree was 8' tall.

My potting mix is a self-made mix combining a 'professional nursery blend' from Lowe's with a few added ingredients of my own:

80% 'professional nursery blend', which list it's ingredients as: Composted wood fines, peat moss, sand, perlite and soil.

20% my own mix of roughly equal parts perlite, compost and composted bark

Will this do the job?

There seems to be fifty different soil combination suggestions, the keys I know are well drained soil and some forms of nutrient giving compost/composted bark.

That link has great information Barbara, but what is Turface? I've never heard of it.

Will

In 1980 I purchased a 1 gallon Picea glauca 'Conica' that had been poorly potted and had some major root exposure that gave a cool gnarled appearance. I re-potted it in a 3 gallon container that year using good old garden soil. Over the years I have thinned out the branches giving it somewhat of a bonsai look. Some years it gets a little fertilizer some years it doesn't. Now it's almost exactly 29 years since I purchased the plant. It's still in the same 3 gallon container with the same garden soil. It certainly is not nursery saleable quality, but is quite healthy. One of these days I'll repot it again.

I have had other conifers in containers where I used quality potting soil and had less success. Just food for thought. :^)

It's used on baseball fields...I've also heard that non-deodorized kitty litter can be used in it's place. Bonsai growers use it in their mix too.

You can search the containers forum, getting so much info your head explodes. Al's mix above is good for long term
container planting but it was too heavy and too difficult for me to gauge water content....

Barbara

Here is a link that might be useful: Where to buy Turface MVP

when i pot conifers into one gals .. from 2.5 inchers ...

i mix 50% peat based mix.. which usually includes perlite and vermiculite ... of a very course grade ... with 50% wood chips from the tree guy ... if he isnt around.. i would buy bark mini chunks ... NOT BARK FINES ...

water goes in the top.. and out the bottom.. hoiking the pot.. makes it feel like NOTHING was retained ...

if there is too much peat.. it will hold too much water.. for conifers... ergo.. root rot ...

you want.. some water retention ... but lots of water drainage ... and LOTS OF AIR ... the bigger your particle size.. the better off you will be ...

your mix doesnt sound like that .... too much FINE material ...

if you still have pots out back ... go tip the plants out of them.. and see what each of your suppliers uses ... that is how i learned... and god knows.. you have enough pots back there... lol ...

take one of bobs pots... lift it.. then go water it.. how much heavier does it get????

fill a pot with moist peat .. then go saturate it... feel the difference??? .. let me know ...

i wonder what the difference is between turface and clay kitty litter .... besides a price ten times as big.... hey will i stuck it into google ...

as a species.. we tend to want to keep pots well watered... and you should know by now.. most conifers do NOT like wet feet.. and therein lies your conundrum .. figure it out .. or choose plants that wont mind .. and you will succeed ..

and do note.. barbs linked mix.. says for woody material .. NOT necessarily trees and conifers... there is a difference ... though i did not study it all .. it may be just fine .... i provided what i do .. not comment on what the other guy does ...

its all about how water moves thru the media ...

good luck

ken

Container growing is a passion of mine - I grow a lot of plants, including conifers and Japanese maples, more or less permanently in containers and do container design professionally. So I've studied container soils pretty extensively :-) I'd urge you read through the threads Barbara linked - they are hugely informative!

I'd question the quality of a potting soil available at Lowe's, labelled 'professional grade' or not. Lowe's is a mass marketer - they do not cater to the professional horticultural trade and tend to focus on very inexpensive suppliers, passing these economies onto the customer. BTW, most professional growers buy custom mixtures in bulk, not anything you find in bags at Lowe's :-) They are blended to their specifications by bulk soil suppliers. But even these custom mixes are not intended for long term container growth - only as long as it takes to keep the plant looking good and get it to market.

I'd be concerned about the amount of compost in your mix. Compost will continue to degrade and breakdown and as it does, it loses pore space and the container loses drainage ability. In a single season container this is not typically a big deal but if you are holding the plants in the container longer than a single growing season, it is. Or can be. Al's gritty mix is ideal for long term container growing and for any woodies, including conifers. If making up your own mix is too much trouble or you only have a few pots to work, then I'd look at something like Gardner& Bloome Acid Planting mix. This is also formulated for woodies, including maples and conifers. I've used this for years with great success myself, only adding more pumice. I prefer pumice to perlite as it tends to have more weight and a uniform particle size and so doesn't float to the top of mix at first watering. Tuface is a high fired clay product - any clay kitty litter (non-scented or non-deodorized, with no additives and definitely avoid the clumping stuff......really the old fashioned kitty litter) should work about as well, but so does pumice or finely crushed gravel. Sand is too fine, vermiculite collapses and perlite floats.

Personally, I think a couple of 'Pendula Bruns' in matching containers would make a stunning entrace to any garden area!

I AGREE WITH THE GAL 100%.. oops ...

you can buy a 40 pound bag of perlite ... its huge.. for about $30 .. last time i did anyway ... store it dry in a clean new garbage can ... it might only last you a decade or so ....

same with vermiculite ... if you really need both ...

and a huge bale of peat is cheap for the volume ... always dampen peat prior to mixing ... but store it dry for a decade or so...

and then mini chunks or wood chips ...

then mix your own ... a very simple mix is simply 1/3 each of peat.. perlite and mini chunks ...

every time you buy a potted plant.. study the structure ... the pro's now what they are doing ...

and then make your own ...

for what the bigboxstore charges you for a couple bags... you can do so much better ... and have 3 times as much ...

never add soil or mother earth to a pot ... i will do a post on this ...

good luck

ken

Thinking I collect potting-soil recipes like most would collect food recipes.

My mix de jour is similar to Ken's:
1/3 Lowe's Pathway Bark,
1/3 perlite and
1/3 coir (An eco-friendly peat alternative! blah-blah-blah)

With 0.25 cups Apex CRFertilizer and 1TBS Micronutrient powder added to each cuft. Still trying to decide if it needs gyp or lime.

Living in an agricultural area with wholesale nurseries too, many of these ingredients are easily obtained from their distributors or our AG Chemical dealers...which makes me one happy girl!

Barbara