rockm

"I see few threads here about oaks,in particular,and I was just wondering,how many years do you have to have them in a container,before the leaves start to get smaller ?"

It depends tremendously on the variety of oak that's being used. Ihave a large collected live oak (Quercus Virginiana) that's been in a container for over 15 years now and has been actively worked as a bonsai for the last seven. Its leaves are 1-2 inches long by about 3/4" wide, which isn't much smaller than "real life."

Smaller leaved oaks, like willow oak (Quercus phellos), California and Virginia live oaks (Quercus agrifolia--this is just one, as California has more than one variety and Quercus virginiana), Cork Oak (Quercus suber) all have small lobed leaves to begin with.

Larger forest oaks, like English oak and North American White oaks and Red oaks, have larger leaves that have to be reduced substantially to make a believable bonsai.

English oaks seem to respond much better to bonsai culture than the more common North American forest oaks, I thnk. Containerization and hard pruning can help keep leaves smaller on English oak, but such practices on some large leaved N. American oaks can actually make leaves bigger, or even huge.

In general, containerization and the accompanying root restriction is what reduces leaf size. Defoliation doesn't, as it is aimed primarily at increasing twigginess or ramification of branches. Hard pruning won't either, as it is used to increase backbudding on the branches and trunk.

Some larger leaved oaks' leaf size can be controlled through moisture retention, that is withholding water when leaves are first expanding in the spring. This practice, however, can also kill the tree and really isn't a great option.

So, all this probably means you should start with an oak species that's better able to adapt to a container and with a larger sized trunk--like over 4 inches in diameter. Taller stock should also be used--like more than two feet tall.

English oak, from what I've seen, is probably the best bet for large leafed oak species, as its leaves can be reduced by more than half. I would highly recommend any of the live oaks for bonsai if you can get one. Quercus Virginiana "fusiformis" or escarpment live oak, native to the uplands of Texas, is I think the best live oak for bonsai. It's cold hardier than the main species and any of the California varieties.

If you're after more "oaky" oaks, I'd use English oak. Finding good sizeable English oak stock with any character value for bonsai, however, is very difficult in North America. The tree isn't native here and is usually grown from ramrod straight nursery stock.

In this country, Willow oak is probably the best, most common oak that will make decent bonsai. It's native to vast stretches of the Eastern U.S. and isn't hard to dig up, as it has shallow roots and gerenally doesn't develop the deep thick tap root that's common with White and Red oak. It's leaves reduce extremely well with containerization, down to an inch of so. This species, in my opinion isn't used nearly enough for bonsai.