I buy the small bark chips at Home Depot, Dixieline, or Armstrong Garden Center. I used to buy big bags of small orchid bark at Flowerdale Nursery when I lived in Orange. Call around to the nurseries, someone is sure to have something suitable.

You might want to watch out for that. Decomposing bark/wood uses a lot of the soil's nitrogen to do that. I'm wondering why do you want to mix in this bark/woodchips? Compost would be better for lightening the soil, if that's what you're trying to accomplish.

This is for container soil/potting mix, not inground garden soil. Compost is NOT recommended for this purpose but composted bark fines are, for the reasons outlined above - durability, texture, aeration and water holding capacity.

Gardengal, what's the reason for not using compost in container soil, is it just the size of the particles or something else?

And what do you think about shredded vs chunky bark fines?

Compost is never fully "finished". It continues to degrade and decompose so the particles do get smaller and smaller. And as that happens, the mix compresses/collapses and you lose porosity and drainage is affected. It is also excessively water retentive compared to other recommended potting mix ingredients and the combination of those two factors leads to problems with container grown plants. So compared to bark, compost lacks durability, texture and aeration. And its water holding capacity is far too high.

If given the choice, I would opt for chunky rather than shredded bark fines. I would expect both the durablity and textural quality superior with chunks than it is with shreds.

This is new - and good - information to me, especially since my whole vegetable/herb garden is grown in pots.

Kate, your vegetables will probably be fine, because they'll be harvested long before the compost finishes breaking down. The bark helps aerate the potting mixture for longer term plantings. Roots grow in the interface between air and water.

You may need to feed your potted vegetables though because most vegetables are heavy feeders and the compost probably won't break down as efficiently in pots.

And compost provides minimal nutrients as well. It is not a fertilizer but classified as a soil amendment (not a soil substitute). It is used primarily to improve the structure and organic matter content of inground soils.

I use a liquid-feed organic fertilizer that seems to do the job. I just put in the tomato plants yesterday, but I didn't have any wood chips to try.