Find a coarse soil that has a high % of conifer bark in it, or add your own. Try going to a large nursery operation and ask if you can buy a few gallons of their mix - it will invariably be superior to the bagged soils based on peat. Perlite, Espoma Soil Perfector, Haydite, pumice, Turface, crushed granite are all useful amendments that can help you build a suitable soil or amend a marginal one.

The Root Work should be done in the spring before buds break, so you have all winter to find suitable soil ingredients.

It's your call - your plant, but I leave manure and compost OUT of container soils because they break down so rapidly and destroy the aeration I try so hard to build into soils (especially woody plant soils) for the long term. They really don't provide anything to container culture you can't provide either organically or chemically w/o compromising drainage/aeration.

If you're worried about extreme cold there, prune the tree after leaves fall so it will fit under a large over-turned cardboard box. With your tree on the garage floor, and the box trapping geothermal heat radiating up through the floor, the plant will survive extreme lows.

I talk to lots of people off forum, and I had a conversation similar to this recently. I remember because of the 'box advice'. Perhaps it was with you and this is redundant?

Al

Sherry,

It may be more economical (in the long run) to build a growing mix for the long-term, as Al suggested. Most commercial growing mixes are peat based. They will breakdown quickly and you will find yourself repotting more frequently.

Last year, I root-pruned a fig tree in a container similar to what you described. It was in a 3g nursery container and had been in there for several years.
{{gwi:45675}}
It ended taking me almost 3 hours (maybe longer, I had to do it over the coarse of two days) to remove the growing mix from the roots with a pair of chopsticks. For comparison, my trees normally take less than five minutes to completely bare-root. There are many threads on methods for root pruning trees both in this forum and the fig forum.

If the trunk of your tree is more than 1.5" in diameter, you will need a larger container. Your local nursery may have a 15g (about 18"D X 15"H) container which would be ideal. If you decide to use a long-term growing mix, you will want to bump up to a larger container at about a 1" diameter trunk. Also, if you are in it for the long-term, you'll want to employ a root-pruning technique which removes all the old growing mix from the roots now, rather than in stages over a few years.

~james

Within 100 miles of my home or homes are a lot of nurseries that propagate and sell plants all over the state. Not one of them produces their own potting soil, though they use a lot of it. Landscape supply companies mix and deliver soil to the nurseries. Many will sell the same mix to you in less than the 20 yard minimum they deliver to the nurseries. As tapla has suggested a nursery may sell you a small amount of their pile. However unless it is a propagating nursery, most of which are wholesale only, you may not get the right mix. I have compared the mixes of several nursery suppliers and they are so closely the same I could not tell the difference. None contain peat or compost, or manure and most will supply a list of what they DO contain. Al

thank you all for your advice; I will wait til spring before root pruning. Last frost here I think is usually mid to end of May. Is that a good time to prune, or before then?
I know of someone in landscaping business, perhaps he can point me in direction of some potting mix. Yep you're right I have all winter to find some. In Maine, that's plenty of time :0)
Sherry

Prune in early spring/late winter at the onset of bud movement this year and note when that is. Next year, do your root pruning a week or two earlier (if you overwinter your plant in the same place).

Al

Al mentioned "conifer bark" for mixing in soil preparation. Can a year old shredded chips of cedar tree branches be added instead of conifer bark in soil preparation, or do cedar chips have some downside? I am asking this because I got a good amount of cedar chips delivered last summer and coming summer I may be potting fig plants rooted this winter.

'Cedar' covers a lot of territory (at least 5 genera I can think of), and most of the trees referred to as cedar in the US aren't cedars. White cedar is Thuja (arborvitae), red cedar is Juniperus (juniper), etc.

I can't answer your question, I've never grown in anything that might be close to cedar chips. Pine, fir, and hemlock BARK are the limits of my bark-based experience. I do have a bit of a bad feeling about it because of all the aromatic bio-compounds in the wood and bark, but don't know if the feeling is legitimate or not. Generally, it's good practice to stay away from sapwood, but .... I've also never seen it mentioned as a suitable bark in any of the texts I've read about container media, either. Sorry. :o(

Al

I got a good amount of cedar chips delivered last summer and coming summer I may be potting fig plants rooted this winter.

Al is correct - if you have any chips in there from a tree that produces chemicals to repel competition (allelopathic), you will be in trouble with your soil. OTOH, you will have decent weed suppression if so.

You also don't know what critters moved in since last year that may find your pot a good, safe home to munch on young roots. In my mind, chips are a good medium for edible mushrooms, and look out for them! Yum! (I still bore people with the story of getting chips dumped at an old GF's house and the next spring morels popped up everywhere).

Dan

I agree that sapwood should be kept out of container soils, but I'm less worried about aromatics and allelopathy (black walnut excepted, of course). Here's an article that attempts to debunk allelopathic effects of Cedrus & Thuja:

The Myth of Allelopathic Wood Chips

Sometimes it's not just the allelopathic properties, either. On another thread, JaG left some good info about hardwood chips and the potential problems (mostly pH & N immobilization, if I remember correctly) with using them fresh in container soils. Though you're not asking about hardwoods, the question is similar because of the effects of a sapwood that would probably break down slowly but might contain growth inhibiting compounds (allelopaths) ..... and so far, we don't know what the composting process (while it's part of a container soil) will do to pH. We don't have the buffering effect of a mineral soil in containers, so the effect would be greater in container soils than if you used them as a garden mulch or incorporated in garden soil.

Al