I wish you'd have noted the tree species?

The cuttings can be almost any size if they're from a plant that is growing well & has lots of stored energy. I have rooted cuttings larger than broomstick size and know that in the south, there is virtually no limit on the how large the cuttings can be - 6" diameter on many species is common. In your zone, cuttings taken just after summer solstice will work best. They have a high carbohydrate content and there is still plenty of good sun left in Jul-Sep to help build roots and store energy for winter. They actually should have the highest carbohydrate content around mid-Sep, but if taken now, light could be an issue, but don't let that stop you.

From what part of the plant is difficult to answer w/o being rather technical. You want wood that is ontogenetically young, which really doesn't have anything to do with chronological age. This wood would be found close to the trunk & low on the tree, but it should have been getting good light exposure (again - the carbohydrate/stored energy thing). For your purposes (and other than large-leafed species like elastica & lyrata), take 6 inch cuttings that are well lignified (woody). It's ok if they terminate in summer wood (this years growth). They should only have a couple of leaves on them to reduce transpirational loss. If the leaves are large, just cut them in half across the veins with a scissors or something sharp.

If I start a cutting in the summer, I never tent it or use rooting hormone - I just put it in bonsai soil (just because that's always the handiest) in bright shade & keep the soil moist. You should root in 100% perlite or something like Turface or Espoma Soil Perfector - something very airy.

The callusing part will vary by plant, but since root primordia initiation is usually along the entire stem below the soil line - it's not necessary.

Don't start in water. Water roots are very different than those that form in an aerated medium, are very brittle, and more often than not are unable to make the transition from water to soil, so die anyway. The effect is that you've wasted a bunch of time & will need to hope the cutting still has enough stored energy to make new roots that are adapted to soil.

Give them as much light as you can w/o exposing them to direct sun. I have a bench on the north side of the garage where I set cuttings. It is shaded by the building walls, but has full exposure to the sky. This is ideal for starting cuttings. Indoors - place under a fluorescent shop light (or equal - incandescents will cook them, btw) with the light no more than 6" away from remaining foliage & keep soil just moist (not soggy).

That cover it?

Al

Species: mostly benjamina and binnendijkii, for what it's worth. Though there is a lyrata at work that I think should be cut back.

I'm guessing that my main problems have been:

1) leaving too much leaf area on the cuttings -- I haven't been removing anything, and

2) rooting medium: I've been using ordinary potting soil at home and at work. At work, they stay too wet, and then begin to rot (often within 24-48 hours); at home they tend to get too dry, though I have marginally better luck with them at home.

Thanks so much for answering.

Ahhh, I forgot - temperature can be important. Cuttings root fastest in media that is kept at 70-75* F.

Al

I just used a small clay pot, I think it was 4" with of course good draining soil. I planted several of the cuttings (6"-7") or so taken from side branches in the spring which were still pliable and green.
One or two cuttings didn't make it for whatever reason, the rest did just fine. I tried rooting in just plain water before that, but they rotted each and every time.
Rooting in soil, the cuttings were not kept constantly moist either. They were allowed to get pretty close to drying out. The cuttings were watered once a week or so when needed. If they are going to root, they do so rather quickly. I had them rooting in bright indirect light.

Billy Rae

I've read lots of negatives about rooting in water but for me it's been the most successful. My now 6 1/2 foot ficus benjamina was done that way, I would have taken new green tips in the spring, 3 nodes, keeping the top two leaves, stuck in water and checked everyday. As soon as I spy a little root nub starting I stick in soil, and they take off from there. I've done this with the variegated version, all my ivies, (even though in the spring they start easily in soil), definitely coleus. I'd read with the ficus lyrata to either roll up the leaf or trim it to reduce moisture loss. Oh, and I change the water every 4/5 days, I think it's a couple of weeks before I see the start of roots.

er.. tapla:

«6" diameter on many species is common»

that seems a wee bit wide in diameter -- I hope you meant 6" long? :P Otherwise, I got some trees I'd like to go chop down and replant!

No - It's kind of difficult to be confused about 6" diameter, and that really is what I meant. In addition to various species of Ficus, many trees in the Salix and Olea genera (just off the top of my head - I'm sure there are more) will also root from fence post size cuttings.

In the link provided, if you still doubt, an acquaintance of mine who lives in Montana describes rooting 4" caliper Ficus cuttings, so it's not much of a stretch to realize that closer to the equator you could root larger diameters.

Al

Here is a link that might be useful: Ficus from cuttings