Root prune advice needed

[Alex_B]

Hello all!

Its been a little while since I've posted (or been generally active) here as I've been quite busy with work (although I typically look through posts when I get the chance), but I am in need of some advice in regards to when is the best time to root prune some of my trees.

I have never root pruned any of my trees before (I've just been slip potting as they are still in development) so I'm not too sure when is the best time of year to root prune the following trees:

- Chinese elm
- Japanese elm
- Dawn redwood
- Shinpaku Juniper (I know its not deciduous but since the rest of them are I thought I would just put this one here too)

I was under the impression that the best time to root prune is in winter just before the buds start to come out for the following autumn. In the past few years I have noticed the buds have been coming up in early to mid August so I was thinking of root pruning all the above trees now (unless its better to prune Junipers later on in the year) but I just wanted to check what everyone else tends to do for these types of trees as I don't want to kill any by mistake.

[Ryceman3]

I’m going to begin root work on my deciduous (also in Melbourne) in the next couple of weeks. Typically I do deciduous first, then move to pines, then juniper afterwards (I don’t have many of these so others with more experience might have other ideas). Any natives get left for the warmer months… I don’t have Dawn Redwood so will leave that for others too.
I seem to get bud swell and new shoots on deciduous by the end of July generally so look to have them done before that. Assuming your trees are in good health, look to prune hard on your elms to get fine roots developing in near your trunk.

[shibui]

I've stopped believing in 'best' time. In practice there's actually much wider window we can do most things, including root pruning, and many of us have discovered that other times of the year are also suitable to do root pruning.

I've been digging and root pruning tridents for several weeks now. I've been root pruning trident maples, Japanese maples, crab apples and most other deciduous trees from mid winter through to leaves opening for many years with no problems.
The Zelkova and dawn redwood should be fine to root prune from now through to when leaves open fully.
I have had occasional problems with Chinese elm root pruned early in our cold winters so now I leave those until closer to spring and that seems to work better. Melbourne is a little warmer than here so it could be OK down there but if you have a choice maybe wait to do that one.

I usually leave the shimpaku junipers till after the deciduous are finished so later in spring but that's more about work load and I know the trees will be OK with later root prune. I've seen others post that they do junipers and pines before deciduous which suggests that they can also cope with a much wider repot window. I think you'd be OK to repot juniper any time from now through to mid spring too.

Just remember that because a tree dies after root pruning does not necessarily mean one caused the other. It is tempting to try to link 2 events but there are lots of things that can go wrong and it is not always the events we see that are cause and effect.

[Alex_B]

I’m going to begin root work on my deciduous (also in Melbourne) in the next couple of weeks. Typically I do deciduous first, then move to pines, then juniper afterwards (I don’t have many of these so others with more experience might have other ideas). Any natives get left for the warmer months… I don’t have Dawn Redwood so will leave that for others too.
I seem to get bud swell and new shoots on deciduous by the end of July generally so look to have them done before that. Assuming your trees are in good health, look to prune hard on your elms to get fine roots developing in near your trunk.

Thanks a lot for the help Ryceman! I will probably start root pruning in the next week or two, once I pick up some more soil. Overall, I'd say my trees are in good health, I had a bit of a bug infestation over summer but I think I managed it okay. The only cause for concern I have is that my backyard gets little to no sunlight in winter so I am always worried about my trees getting water logged. I try to make sure this doesn't happen by keeping a close eye on them but the soil can stay moist for a week if there is not much sun.

I've stopped believing in 'best' time. In practice there's actually much wider window we can do most things, including root pruning, and many of us have discovered that other times of the year are also suitable to do root pruning.

I've been digging and root pruning tridents for several weeks now. I've been root pruning trident maples, Japanese maples, crab apples and most other deciduous trees from mid winter through to leaves opening for many years with no problems.
The Zelkova and dawn redwood should be fine to root prune from now through to when leaves open fully.
I have had occasional problems with Chinese elm root pruned early in our cold winters so now I leave those until closer to spring and that seems to work better. Melbourne is a little warmer than here so it could be OK down there but if you have a choice maybe wait to do that one.

I usually leave the shimpaku junipers till after the deciduous are finished so later in spring but that's more about work load and I know the trees will be OK with later root prune. I've seen others post that they do junipers and pines before deciduous which suggests that they can also cope with a much wider repot window. I think you'd be OK to repot juniper any time from now through to mid spring too.

Just remember that because a tree dies after root pruning does not necessarily mean one caused the other. It is tempting to try to link 2 events but there are lots of things that can go wrong and it is not always the events we see that are cause and effect.

Thanks a lot for the help Neil! Its good to know that I can root prune the redwood at around the same time as my other deciduous trees. I will probably wait another week or two before pruning so I should hopefully be alright with my Chinese elm.

Its good to know about the large root pruning window for shimpaku junipers as I just wired my juniper and I don't really want to disturb it until later in August.

I am hoping none of them die but if they do there isn't much I can do. As I said above, if anything kills them it will be the lack of sunlight for long hours in my backyard.