Mirabelle Plum, Cuttings 2022 (Prunus Domestica subsp. Syriaca)

[Joshua]

This bushy Mirabelle Plum grows in a fairly shady area at the bottom of my street. It's made some nice fruit the last couple of years.

tree.jpeg

I've been pretty keen on growing some in a pot on my balcony for a while and finally went to get some hardwood cuttings today (winter here). I read somewhere here that prunus in general can tolerate a lack of sun and I think I remember also reading that they're not too difficult.

Noticed that some of the flower buds had almost started to bloom so didn't want to leave it any later.

I have no idea what makes a good cutting, but heard that pencil thick straight sections are the way to go. There were a lot of really small twiggy branches that appeared to have buds (mostly flower buds from what I can tell), coming off slightly thicker branches. I took a bit of a mix and I'm sure there were at least a couple of good ones in there.

Here's the loot:

cuttings 1.jpeg

cuttings 2.jpeg

cuttings 3.jpeg

I put them in these 20cm deep pots with a mix of coco coir and perlite (about half half but a bit more coco).

pots.jpeg

I cut them mostly into about 20cm sections, each time on an angle just below a node, removing any little branchlets and flower buds, and soaked the bottom 2/3 in a solution of Osyril.
(I have no idea what this stuff is but it's sold here as 'root growth stimulator'. I can't seem to find rooting hormone here).
I was going to dip the ends in honey too but forgot.
I planted them with about 1/3 of the cutting sticking out, watered, then tipped the Osyril solution in after watering.

Here they are planted.

potted.jpeg

Should I cover them with a plastic bag to keep the humidity, or is that really only for when there are leaves? I've seen conflicting opinions on this. I'm doing it anyway for now unless someone tells me it's a bad idea

I'm keeping them outside in a shaded but bright spot on the balcony. I think I read somewhere that if inside in the warm that will encourage the leaves to take off too early compared to the roots.

Will post an update if take off

[Matt S]

Great post Joshua, keep us posted on your progress.

I'm the last person to give advice on propagating deciduous trees, so I'll leave that to others, but I enjoy seeing other people's attempts.

Matt.

[shibui]

The plums I have tried have all been easy to strike as cuttings.
As you mentioned, straight, pencil thick sections are usually used because those are usually vegetative wood without flower buds but any parts can strike roots. Cuttings 3 shows the type of cuttings I usually look for. Those with small side shoots are probably older, flowering wood and strike rates may be a little lower.
I am surprised that you cannot find rooting hormones in your area. I just searched and see that powder, liquid and gel formulae are available. Plums usually have enough natural rooting auxins already for good success. The Osyril you have does not appear to have any IBA or NAA which are the 2 common rooting compounds but it should not hurt and the product claims to help so hopefully it will.

I get better strike rates when I keep humidity high as even dormant cuttings still transpire slowly and can dehydrate before new roots form. I have automatic misting for cuttings but plastic bags will do the same thing. Some people open the bag every week or so to allow fresh air to deter fungal problems and to check soil moisture. Just watch for any sign of mildew or mould on the cuttings. If you see anything suspicious a spray with Hydrogen peroxide is a great antibiotic for seedlings and cuttings.

It is generally believed that flowers waste energy that could be used for roots so most growers pick off any flower buds if they develop on cuttings.

Outside is probably the best place but make sure they do not get full sun a the plastic bags can heat up quick.
Best results are when soil is slightly warmer than the tops but that's hard to manage unless you have bottom heat. Most cuttings will be fine in ambient temperature and plum should be fine.

Good luck with striking these plums. If this lot does not work well you should try some summer cuttings. They strike much quicker but definitely need added humidity. With plastic bag covers you can still get good results from summer cuttings.

[Joshua]

Thanks for the advice!
Only about two weeks later and they're already starting to shoot. Almost all of them too.

Now I guess the hard part will be keeping them alive until they're ready for a repot (and beyond).

I've been keeping them on the balcony with ziploc bags on top. Initially they were under a bench but I decided they should probably get a little more sun than that, so moved them up. They're partly shaded from morning sun by another plant, and from midday sun by an empty trellis. Full shade (bright indirect light) in the afternoon.

Night temperatures have been consistently above zero for at least a week and day temperatures have gone up to around 17 a couple of days, although it looks like it might cool off again soon (I'll also note that fungus gnats, fruit flies, aphids and spiders are all clearly already enjoying this).

I took off the bags briefly a couple times per week. I'll start doing that a little more often and for longer.

I picked off a few buds then realised I should probably read up on the difference between flower and leaf buds. I was guessing pretty correctly but might have taken off a couple of the wrong ones.

Interesting to notice that some of the thin ones I thought weren't going to work at all are shooting with more leaves, and more quickly, than the others.

Just showing one of the two pots. They're all a bit slower in the other one and couldn't get a decent photo anyway.

20220206 Mirabelle first shoots.jpeg

I am surprised that you cannot find rooting hormones in your area.

I admit I didn't look online, just that in the main commercial garden shops I wasn't able to find much. One day I'll look for and ask about those particular compounds or just order online. For now not too worried because it's optional and more for optimising and improving the success rate.

[shibui]

Plums are definitely easier so, as a veteran cutting grower it is hard to see why you were even concerned. Obviously the benefit of hindsight.

Great to hear that your cuttings are doing well.
The move to more sun is good because the leaves can now produce food and help the new plants grow.
Changing air and gradual adjust to life without a plastic bag is also textbook propagation technique.
I'm guessing these are probably over the worst so chances are you already have new plants.

[Joshua]

Bit of an update. Several have just died off and the rest don't look great.
I suspect that most are just because the cuttings were too thin and didn't have enough energy to begin with. Also perhaps I should have started introducing a bit of fertiliser earlier.
Of the initial 19, 17 started growing leaves. Now there are 6/7 are still alive but don't look promising either.

Any general advice for caring for these?
Also if any survive and start looking healthy, when should I consider repotting?

20220804 mirabelle cuttings progress d.jpeg

20220804 mirabelle cuttings progress b.jpeg

20220804 mirabelle cuttings progress a.jpeg

Cheers

[shibui]

Some of the remaining cuttings look OK. Just keep caring for them. Water when to soil start to dry, high humidity around the leaves if possible.
Maybe you transitioned to no dome a bit too early before they had started roots.
Maybe the mix was not right. Potting soil or garden soil often have diseases in them that can infect cuttings.

You could try again with fresh twigs. A bit later in spring is a good time when the new shoots have hardened up a bit.

[Joshua]

Summer here is over and here is the growth of the two survivors.
I think my mix for the cuttings was less than ideal but these two managed to get a few roots to the bottom of the pot - signal for me to pot them into something more fertile and that holds less water.
That was toward the end of June, just before we went on holiday and just when it was starting to get really hot. The neighbor clearly did a good job watering them and when we got back I almost didn't recognise them.
Decided to post these photos before they lose their leaves in autumn. Days are now shorter than nights, temps are now in the 15-24 range and the growth has slowed right down.

Both pots are 16cm diameter.
The taller of the two plums is 1m06 above the soil surface.

20221001 b.jpeg

20221001 a.jpeg

[KIRKY]

Looks like success, and a lot more cuttings available for a nice plum forest. Thank for the update
Cheers
Kirky

[Joshua]

At some point during autumn I slip-potted these up, which I probably should have done a bit earlier in the growing season so maybe it was pointless at that time.
One in a 30cm nursery pot but kept around the same depth of medium (about 12cm).
The other in a 30cm wide bucket which was previously used as a wicking bucket for another plant, and this one a little deeper (maybe around 20cm).
Still just in plain potting soil.

Now we're getting toward the later end of winter, some buds have started forming, so I decided to trunk-chop them both, taking some more cuttings along the way.
I'd say they are slightly over pencil thick.

Some questions because I'm hesitating about repotting.

I've read that the best time to do so is before but break, like for the trunk chop. Just not sure if it's a good idea to do at the same time as the trunk chop for this species. I assume it IS ok because I hear that plums are generally quite hardy and forgiving.

So in general for plums:
- is it ok to trunk chop (or any top-prune) and root prune at the same time?

In this case,
- Should I leave them alone until next year?
- Or should I also take the opportunity now to repot and get them into a better medium?
- If so, how aggresively should I root prune?
- And how to manage after-care?


Photos below of the now planted cuttings (next to some newly planted mel seeds), and the remaining stumps with a wine bottle cork for size reference.

Treating the cuttings different to last time:
- They are in individual small pots instead of grouped together.
- Kept indoors a mini greenhouse instead of covring with a bottle
- There are fewer of them and shorter than last time but more consistently straight pencil thick sections.
- Two are shorter but include the Y section of the previous on that had some branches.

They are in a little a mix of roughly.
- 1 part my current bonsai mix which is just various bits and pieces mostly inorganic (some seramis, pumice, scoria, chabasai, bits of pin bark, some osmocote that found its way in there)
- 1 part seramis
- 1 part coco coir
- 1 part worm castings

2023-01-29 new cuttings.jpeg

2023-01-29 after trunk chop 1.jpeg

2023-01-29 after trunk chop 2.jpeg

[shibui]

I regularly chop and dig (root prune) feral prunus down here and have very few deaths with them so I'm confident we can do both in the same operation.
Mild climate down here and I can chop plums (and many other species) from mid winter right through to leaves opening.
Plums are very strong and resilient so they can cope with drastic root reduction. I take every opportunity to root prune trees destined for bonsai. basically every repot is a good root prune to set up roots for future nebari. That means removing down roots and shortening any strong roots to get more root ramification.
After care for deciduous trees is to put them back on the bench in full sun. No need for special treatment as they are dormant. By the time leaves unfold the roots have already started growing and the trees don't need special attention by then.

Have fun with your plums. Watto will be proud of you for choosing to work with plum species.

[KIRKY]

Agree with Neil, they are tough. As your growing season is much shorter to ours, I would do them now in order for them to be already set up for Spring. I cut all downward growing root shorten side roots and comb out top roots for future nebari.
Cheers
Kirky

[Joshua]

Thanks Kirky and Shibui.
Did the first one of two this morning.
I can't remember what I did when repotting the cuttings the first time, but the rootball was kind of flat right under the trunk. Then it quickly all went down around the edges of the relatively small pot that it had been in most of the year.
There were two thick roots branching left and right, both of which I cut right back.
At the end you can see that some roots on one side are higher up than on the other, so used that to determine the angle of the trunk when planting.

It was probably unnecessary but I cut out a disc from an old bucket lid about 8-10cm, and planted it on top of that.

Not sure if this was too aggresive or if I could have gone further. I'll do the next one sometime within the next week.
Photos not great because early morning, it was only just getting light.

plum 2023-02-02 1 start.jpeg

plum 2023-02-02 2 start.jpeg

Looking up from underneath here you can see those two thick roots going right and left.

plum 2023-02-02 2b thick roots cut.jpeg

And here where I initially cut those off

plum 2023-02-02 3 after root prune1.jpeg

Finished the root prune view from the top

plum 2023-02-02 4 after root prune 2.jpeg

and from the side you can see the difference in height.

plum 2023-02-02 5 planting.jpeg

Planting angle just before covering with more mix.

[KIRKY]

Well you had a lot of good healthy roots. I don’t think you were too aggressive at all. A good start for future nebari. Now just let it settle. Remember it has less roots so will not require too much in the way of water. Assuming it’s not too hot indoors heaters etc…
You should see buds in the next what 4-6 weeks? When your Spring starts? Once you see the buds start to swell start feeding and increase watering.
Cheers
Kirky

[Joshua]

Cheers. I'll do more or less the same for the other one.
Actually I've put it back out on the balcony not keeping it indoors.
Same for the cuttings actually. At first had them indoors but figured it's more natural for them outdoors and probably less chance of them going moldy since I'm also trying to keep them humid.
Not sure when it should start budding but will try to update here when they do.