Saturday, June 25, 2011

Tweaking thinking

After a few more emails and questions, the thought occurred to me that presenting these ideas may make this a bit more logical to readers, so here goes!

Why should wrapping cuttings and maintaining them in the lower temperatures work better?

First, remember the instructions on packaged bare roots about mounding? The idea is keeping the plant cool, dark and damp stimulates the formation of roots instead of top growth. Absence of light and heat combined with dampness is what roots grow in. Adding heat and light stimulate leaf, cane and flower bud growth.

Wrapping the cuttings in damp paper simulates damp earth, as does the darkness. Keeping them cooler prevents formation of the chemicals which trigger top growth, favoring the formation of callus and roots instead. The cuttings already contain the programming to form callus which further develops into roots. Providing them the appropriate conditions to favor that kind of development speeds the process along. Holding them in higher or warmer temperatures stimulates both growth and callus, often the former at the disadvantage of the latter.

The whole reason for the rose to grow is to create flowers. The whole reason for the creation of flowers is to attract pollinators to create seed and perpetuate the species before the plant dies. Pollinators and the plants evolved together. The more successful roses broke into growth and flower as the appropriate pollinators arrived. Both were stimulated into the appropriate state of development simultaneously. Providing different conditions than those outside "trick" the rose into doing what is wanted from it, much like the Romans passing steam under potted roses to force them into flower out of season. Also, much like forcing Paper White Narcissus into flower earlier than usual for the holidays.

If your temperatures are already higher than the suggested sixty to almost seventy degree temperature range which I've found beneficial, why not wrap them, and presuming you have enough room, put them in your vegetable crisper? Prevent them from freezing, of course, but the cooler temperatures in the fridge should also stimulate callusing, though probably at a slower rate. Rose roots continue growing in near freezing soil. Not as quickly as they do in warmer soil, but they do still grow. You might find the need to hold them for three weeks at the lower temps than is optimal at the upper end of the suggested range. Only experimentation will determine that.

I've been repeatedly asked about my potting soil. I have some humidity and more than a little heat. Though no where near as extreme as many other places, it does get HOT here now. The evaporation rates are quite high, yet the evenings remain cooler and even with the heat, it is still humid enough to rot plants sealed under plastic or inside a terrarium. For these reasons, I use moisture control potting soil. If your humidity is greater so evaporation is slower, that man remain too wet for the conditions, rotting the cuttings. Many years ago when propagating for The Huntington Library as a volunteer, using their mist propagator, we used half coarse builders sand and half perlite. It remained damp after the water drained through it, but it also had a lot of air space in the mix so the cuttings didn't rot.

I've known people who tried to replicate the mist propagator and failed because of using organic based soil mix. Continuous wetness causes organics to sour. Dampness works, constant watering, doesn't. The wetter and more humid it is, the more open and fast draining you need your soil mix to be. Same holds for cool temps. Hotter and drier makes for greater evaporation, hence greater water holding capabilities.

It's dramatic the difference humidity makes. My old climate had none (usually) and required keeping everything covered in plastic or they'd die nearly immediately. Here, covering anything in plastic results in it molding nearly immediately. I've never been able to just stick any kind of cutting in a pot in the shade and have it root, but I've done it with hibiscus over winter. I'm going to mess with Mutabilis this winter attempting the same thing. I figured I'd have to put callused rose cuttings under plastic once planted out, but they're forming roots with half day full sun in foam cups. That wouldn't have happened in Santa Clarita. But, then, I never had the fungal issues there I have here, so the humidity is far different. I can FEEL it here, I couldn't there 99% of the time.

The best way is to get a handle on your humidity and how it varies with the year (presuming it does). Surf and absorb all the various methods you find explained and develop one combining the best of all of them, tweaked to your heat and humidity, then begin experimenting with it to see how it has to evolve to work where you are with what you are trying to propagate. 

Once you figure out your humidity and evaporation rate, you can determine what kind of soil is best for you to use. You can also decide whether or not you need to cover the cuttings once callused. I'm finding planting them deeply in the soil to maintain cooler, damper, darker conditions, is working quite well without rotting or drying out before rooting. Think of the cutting in terms of a bare root plant as they really do require the same conditions until they form the root system necessary to support the leafed out plant.


  1. Such a GREAT blog! I just spent the day planting some new bushes and relocating two others... I have some cuttings of a florist's rose (Exotica) in my fridge as we speak. They have gigantic sentimental meaning and I hope they work out.

    Question: Do you ever propagate roses from troot cuttings? I shovel-prunes a 'Graham Thomas' and got several 'Dr Huey' plants in the old space. I desperately want to get an I. X. L. going and I have a tree rose from which I removed the grafted section. I realize the buds have all been removed to prevent the stock from taking over, but I hoped...

    Looks like there won't be any new sprouts up top.

    What if I cut the rose WAY back, so there's ONLY roots? Could I encourage roots to sprout?

  2. I have roots from the wrapped cuttings, you mailed! I bought 32 oz styrofoam cups. I will put a small amount of pea gravel in the bottom, sand and soil mix.

    We have such humidity here that, we won't even mention it!

    And I can stick plants straight into the ground to root. Most do well that way. But since some of these cuttings will go to tornado victims gardens. I will do cups for these babies!

    Thanks for all the info!

  3. Checked the humidity, its down to 91% right now, outside. ;)

  4. Jedediah, it is possible to propagate many of them from root cuttings. Dr. Huey, as you've experienced, comes up from the root VERY easily. It seems every root from a Huey budded plant that's been removed, sprouts to form World Class plants of him. If you visit gardens where the "gardeners" cultivate under the roses, you'll find hundreds of new Huey plants sprouting from the broken feeder roots. It's a battle I've fought for many years! Unfortunately, it gives that root stock a bad name it really doesn't deserve. You can't fault the root stock for doing what it's supposed to do after someone who doesn't understand what they're doing causes it.

    I wish you'd tried budding on your tree rose before removing the scion. It could have been possible to bud underneath the original graft if the bark wasn't too thick and woody, leaving the original budded rose there to act like the original parts of the trunk stock to feed the plant and keep the sap flowing while the buds knitted. Unless you luck out and have a fortuitous bud break into growth toward the top, I'm afraid that trunk is history.

    Yes, you should be able to cut off the old trunk and have Huey sprout up from the remaining roots, very much like what you experienced from the remaining roots of the Graham Thomas plant you removed. Any damage to the roots can easily trigger them to begin growing, which in a garden sense is a bad thing, but when viewed from the survival of the plant, is exactly what you'd want. What benefit would a plant be if all you had to do is disturb the roots and it died?

    Of course you know if you get plants of Huey going from those roots, they'll have all the original growth buds you'll have to remove before being able to bud on it? Otherwise, you'll have suckers of Huey everywhere. If you want to try using what you already have, you can encourage long whips of the old root stock to grow, then process them as I showed in the longer cutting wrap entry here to create your own tree trunks. The benefits of using your Huey is you already have it and it is less prone to sun burning than IXL is. The downsides are you don't know if it is virus infected which could transmit the infection to the roses you bud on it; and Huey slows the sap flow much over three feet so you wouldn't be able to as easily make taller trees, if that's what you want.

    Hey Kimmie! Congratulations on the roots! Just be sure to poke enough drainage holes in the cups. I think it's wonderful your wanting to share the wealth with those so terribly damaged by the tornados. Thank you! I hope you get tremendous takes from the cuttings so their gardens can begin feeding their souls as the rest of their lives begin to also heal. Growing up with those storms, I well remember the terror while they happened and the devastation left in their paths. We have earthquakes (I HATE THEM!) and I'm honestly not sure which I could be more comfortable with. I guess it's the earthquakes as we really only have a "big one" every couple of decades where you have twisters every year. No thanks!

    Your higher humidity should help keep the plants actively growing while the roots form. I'm thrilled thinking of all those roses "seeded" around your area. That is NEAT! Thanks! Kim

  5. But I don't want 'Dr Huey'. I thought rose trees were IXL stock. I just want IXL. I know I can special order it from my favorite nursery, but that's over $50 and an 18 to 24 months wait.

    Sad about the beheading. A thought, though. Why would grafting fresh material to the old trunk stimulate new buds on the trunk? If it's food for the trunk, wouldn't the existing graft (in this case it was ('French Lace' which I find boring) have performed the same function? Or am I misunderstanding?

    Never the less... You're a true gem! Thanks for your advice.

  6. Hi Jedediah, unfortunately, AND fortunately, I don't know of any commercial producer who uses IXL for anything. It took too much room and is too susceptible to sun scald, causing losses in the fields and people complaining about "defective plants". There isn't anywhere I can tell you to special order one. You'll just have to make it yourself!

    IF the old French Lace was still atop that standard, it would have functioned like the remaining growth on the original plant. Thanks for the kind words! Much appreciated! Kim