Cork Oak

Last year I did some initial cutback and wiring on a cork oak that was one year out of the ground (see “Stimulating new buds on cork oak” for details).

The tree has grown well over the past year and is now ready for another cutback.

Cork oak

The part of the tree I’m most interested in developing at this stage is the apex. Here’s a close-up of the area I cut back to last year.

New shoots near former apex

As you can see, the trunk is straight in this section. Or maybe you can’t see – let’s clear away the new shoots to get a better view.

After removing new shoots

I’ve decided to use the curvy branch on the left for a new apex so I won’t need branches above this point.

New apex

Once the new apex thickens, I’ll remove the top of the trunk by cutting between the new apex and the branch indicated on the right.

Top branch on the right side of the tree

Once that was settled, I reduced the strong shoots emerging from the top of the old apex.

After cutback

Some wiring added shape to the future branches.

After wiring

Here’s a closer look.

After wiring – close-up

To get a better idea of what the tree will look like after I remove the old leader, I covered it up with a towel.

The future trunk line

I’ll let the tree grow for another year at this point as the apex and main branches need to thicken.

My recent posts on cork oaks feature trees that were removed from the ground this past winter. The goal for those trees is to simply get healthy and develop strong roots so they can withstand further work next year.

The cork oak below was removed from the ground in 2015 – one year earlier. The tree is strong but lacks branches low on the trunk.

Cork oak – 18 months out of the ground

Cork oak typically sprout buds where they are cut. Here are two examples of this where branches were cut when the tree was dug.

Two branches emerging below the cut

Five branches emerging below a cut

To stimulate lower branches, I removed the long, straight portion of the trunk.

After shortening the trunk

I’ll let the remaining branches run for the time being but will wire them so they develop some movement close to the trunk. I’m not sure if I’ll use these branches or not at this point, but I do know that I need a new leader which will require time to develop.

I also have a feeling the angle of the trunk will change during the next repotting. I don’t like it when the trunk emerges straight up from the soil. By tilting the tree to the left, I can create movement and get a better idea of where I want the future branches to emerge.

Tilted to the left

That’s it for the time being. I’ll continue to feed the tree heavily this year in hopes of stimulating new branches and will work with what I get when it’s time for the next round of improvements.

This past winter I picked up some field-grown cork oaks. Most of the soil fell away from the roots when they were dug so I potted them the day they arrived. The one question I had at the time was whether or not to remove the leaves.

I’d seen the question posted a number of times and have heard responses suggesting both approaches. For this batch, I decided to keep all of the leaves. Oaks tend to drop their leaves in spring when new growth emerges so I figured it was only a matter of time before they fell off on their own.

I potted the trees in bonsai soil (pumice, lava, akadama) with extra pumice and left them in a sunny spot on the ground.

Within weeks, one tree lost had lost a few leaves, two trees had lost most of their leaves, and the leaves on the fourth tree died but didn’t fall off – typically a very bad sign.

Two months on, it’s easy to tell which trees are which.

Cork oak – this one kept its leaves

Cork oak – this one lost its leaves quickly

This one also lost its leaves quickly

The leaves on this oak died but did not immediately fall off

The first tree, the one that kept its leaves, began growing quickly – the new shoots are now several inches long. The two that lost their leaves are budding well and are off to a good start, though they are moving slowly compared to the tree that didn’t lose its leaves.

The fourth tree doesn’t look good. It had very few roots and showed no signs of life until recently. Just this morning, I thought I saw that a few buds had started swelling. Will report back on that one.

I’ll try removing the leaves from the next batch I work on, but for now the big takeaway is to generate the best roots possible before digging. The more healthy a tree is before digging, and the more fine roots that are close to the trunk, the better.

New buds

Spring growth – note the discoloration on the old leaves that are about to fall off

One great characteristic of cork oak is that they can bud from old wood. I was happy to see many new buds appear along the trunk. The one surprise was that buds can emerge directly from large cuts.

Bud emerging where the trunk was cut

Buds emerging low on the trunk

For now I’m letting the new shoots mature a bit – even a slight touch at this point can break them. The next step will be to thin and wire the branches that will become part of the final design – more on that when the time comes.