Wednesday, August 24, 2011

Hot Weather Wrapping

I've had several questions about success rates, or lack thereof, using this method in hot weather. I'm also finding high heat not only disadvantageous to wrapping itself, but also in succeeding in bringing them from the callus stage to a rooted plant.

I'm doing my best not to use extra electricity this summer running the air conditioning when regulating windows and fans are keeping it livable. The extra 50% increase in power costs to artificially cool the place really makes a difference! The extra power also offends my sustainability senses. Whatever the source of the power being used to create the electricity, I'm not sure I want to use it, saving it for when I can't get by OK without it. So far, so good.

All this is shared to explain this...even the lovely, dark, cool work room isn't able to remain in the temperature range I've found most beneficial for callusing without using the a/c to keep it there. My experiments with refrigerating cuttings haven't been any better than the reports I've received. I'm not sure if the average fridge keeps them too cold for callus to form, but that is seeming the case. I don't have any kind of root cellar nor anywhere to create a temporary one which might provide the appropriate temperatures required, so I'm waiting until cooler weather periods to wrap any more material.

Even if I could successfully callus cuttings now, the heat we're experiencing is not conducive to being able to carry them further. When day temps remained around eighty degrees F or lower, it wasn't an issue. They formed their roots and began growing acceptably. Those patterns are gone for a while. Today, it's supposed to be 104 F here, with up to 107 by the end of the week, and they're threatening to add humidity to the mix, something we traditionally don't have to worry much about.

These hotter temperatures have sucked the life out of many of the cuttings which had successfully callused not that long ago. There are several potential causes I can think of.

It appears more dormant to semi dormant material calluses more successfully than softer, more actively growing ones do. Perhaps it's due to their containing higher levels of nutrients stored in the wood which would otherwise have been used to break dormancy when the weather triggered it? It could be the softer material doesn't have these stored resources and are more susceptible to using up what they do have just to remain alive and aren't able to form the necessary roots before they collapse. Almost like trying to force a bare root into growth too quickly, stimulating it to use up its stored resources to leaf out, form flowers and collapse. I've had many soft wood cuttings during the hotter summer months using other methods leaf out, set blooms and die, so the pattern seems to hold.

Perhaps the softer, more actively growing material has too high levels of auxins and hormones which stimulate the faster growth at the expense of rooting? My experiences using mist propagation showed the actively growing cuttings rooted in as little as seven to ten days from stems which had just dropped their flowers this time of the year. Harder wood cuttings often wouldn't root under mist in weather like this, but would root in winter at much slower rates, sometimes all winter. Those cuttings were under a regular mist of fog which prevented them from drying out and scorching and were in full sun so all green parts of the cutting were providing photosynthesis to maintain it while it formed roots and began supporting itself. Wrapping the way I have been doesn't provide the mist or very high humidity, and I have found planting the cuttings deeply in the cups or pots prevented them from drying out before the roots formed. This would reduce their ability to provide themselves food via photosynthesis while they root.

It could be there are pathogens at work we don't see as much when temperatures are lower. Botrytis and Downey Mildew can both significantly reduce the success rate of propagation no matter what method you use. Some of the results have almost looked like Fire Blight on some of the cuttings. The weather has been suitable for that issue, cool and damp, hotter and damp, repeat. The evergreen Pears are definitely showing those effects in the neighborhood.

I don't spray anything. Not a value judgement if you do as I know there are many environments you can't grow roses in without chemical assistance. Spraying just doesn't fit in with my climate, wind, allergies and sensitivities, nor budget. If it won't grow here without chemical intervention, it isn't going to hang around long. I won't spend the money for them and I'm sure not going to spend the money on doctors visits resulting from the reactions I have to chemicals with increasing regularity.

It might be possible to prevent whatever potential pathogen might be at work on the cuttings by spraying with a fungicide, or not. I won't know as I don't own any fungicides. I can't spray any with these temperatures and wind and I'm not willing to experience any potential effects I might (probably will) have from exposure to them. If you are exploring this method in a hotter area and having the same disappointing low to zero success rate and you spray, please consider including the cuttings in your regimen and report back what the results were. It might make important contributions to the knowledge base about it.

I think I'm also finding specific varietal differences to wrapping in hot weather as I know to be the case in cooler weather. The last batch of unnamed China cuttings I callused and planted have had significantly different results from each other. One rooted and began developing into viable plants, at a much lower percentage of success than earlier in cooler, damper weather, but they have seemed willing to perform. The other, handled and treated exactly the same as the first and done at the same time, limped along, complaining the entire time and all but one cutting has turned black and failed. The jury is still out on the lone survivor. Perhaps the second variety just isn't as successful at creating its own roots and possibly would be better budded than own root? Perhaps it isn't as forgiving about being pushed to root in hot weather as the first? Maybe it had a higher level of pathogen exposure then the other? I honestly don't know. This is definitely going to take a lot more exploration, experimentation and observation.

I will be very interested hearing others' experiences from other climates and from those who spray and will include the cuttings in their spray program. None of us can provide all the potential variations in climate, culture or potential fungi and bacteria. Pooling the results and observations should help to lead to the discoveries of what may work in these hotter times. At least, I hope so and I'll definitely enjoy hearing others' experiences, theories and results. Stay tuned!


  1. As soon as we read about the wrapping method my friend and I were interested in trying it. I had always planted my cuttings straight into a large container of potting soil. She had another method. When I needed to cut a limb off of Lafter I decided it was a good time to try this. All but a couple callused and I potted them into groups in larger containers, and some which rooted were put in smaller pots alone. I was disappointed when some of them turned black because I thought I would have 100% success rate with wrapping. However, I did have a success rate which bypassed my stick-them-in-soil method. I stretched out the planting over a week or two because I didn't have time to pot them all at once. It seemed that the ones I potted first did better than those which were wrapped longer. After nearly two months of mostly 100+ degrees here many of them have put on growth and are doing well. As long as I keep them moist and in bright shade. I know you wanted to hear from people who spray the roses, but I do not. My friend read that you were looking for others who have tried the method and urged me to write. Lafter is the only one I have tried so far. I plan to try all my roses sooner or later. Mutabilis is always requested at plant swaps, but I have the least luck with this one making cuttings via my regular method. I hope wrapping will give me plenty extras. Have enjoyed this method though. Thank you for making it available for the rest of us ! oh, almost forgot to mention...I kept my wrapped cuttings in the pantry, and although we use a/c, it is usually around 78-79 degrees.

  2. Hi Patty, great! If you've had this kind of success with longer wrapped time and higher heat, you're doing better than I am! Once it got hot here, my success rate tanked. I'm happy it's made it easier for you and your friend to get things to root. Imagine how much more easily they will propagate when the conditions get back to more optimal for the method!

    Thank you for sharing your experiences with me (and all who follow this). Your contribution adds greatly to the combined knowledge and will help formulate better guidelines for using it.

    I think you're going to find roses which were more difficult to propagate using other methods will callus better when wrapped. There will be some which just aren't going to cooperate. That's a given. We won't know which they are until more people try more varieties. Mutabilis callused and rooted for me this past winter into early spring. Later, in higher heat, it thumbed its nose at me and just turned black.

    Thanks, again, for providing such detailed information! I am eager to read your future success when time and conditions are more favorable! Kim

  3. I had a difficult time finding the specific blog entry. I hope you get this...

    A very quick question. In commercially produced standard roses, is the trunk stock own root or is it interstock on something like 'Dr Huey' or another variety> I've been craving a plant of IXRL for a long time, but never found one. I thought if I cut off the grafted rose on a standard I have ('French Lace', I might get buds to break. You and Gregg at Vintage let me know that the stock had been disbudded so no new breaks would strike. Point taken. I went ahead and decapitated my tree rose with the idea that I might get the roots to send up sprouts. I had this experience with a David Austin rose I'd shovel pruned...

    The roots have sprouted as I'd expected. I have three robust baby plants.

    The question now is... What are they likely to be? I didn't see a graft union on the root end of this tree rose, only the FL end... Any thoughts?

  4. Most likely, what you have is Dr. Huey. It's the most common root stock for US production whether it's for bushes or standards. It's common to root whips of Huey then bud the trees on them the following summer. Where do you live? Is it the right time for you to root cuttings? I have IXLR material I can share for the postage if you'd be interested.

  5. I live in San Francisco.
    I have very mixed results trying to root my own material... That said, I had some purple-leafed plum branches I used to make woven hurdles in my garden. All of the vertical twigs have rooted and now I have a purple-leafed plum hedge... maybe if I just bury the IXLR whips in the damp soil over the winter, I can get a rooted plant?

    I follow your blog and have noticed how easily the wrapped IXLR canes root... Maybe I can try again... When is a good time?

    And THANK-YOU for your kind offer!

  6. Is there somewhere for you to keep them wrapped where they will remain cooler than 70 degrees for the two weeks? Warmer than a refrigerator, but less than seventy? I know here, there is no where as the workroom heats up warmer than the ideal sixty to sixty seven or eight degrees right now. That seems to be the optimum range for callusing. I'll bet your plum hedge is marvelous!

  7. I sorted through the pot ghetto this afternoon, Jedediah and found I have a rooted piece of the IXL if you're interested. I haven't budded on it, so it should have the same chances of remaining VI as it came to me with. If you'll send me your contact information and when a good time for you to receive an unpotted plant via mail, we can make it happen.

  8. I'm at home on Wednesdays. I can get a rooted plant safe and planted right away. How do I send you my address and such... not publicly.

    BTW, we've e-mailed each other via HMF a couple times. My name is Jeff.

  9. Hi Jeff, I searched through my private messages on HMF and didn't find any between us. Feel free to either send the information through there or my email is this screen name at america on line. That work?