Rooting Tips From Curt (Version (THML 7/24/2011)
Here is some info that I hope will help those of you that are rooting cuttings. As most know Bobby DuPont and I root most or all of our hibiscus. Depending on the variety and conditions, figure 4 to 6 weeks.
1. Healthy plant material is a big factor on what will root well. When you can, pinch the tips out of the plants you want to root several weeks ahead of time. This way the whole plant is responding to the 'cut' and it's hormones are kicked in. Wood with already sprouting baby leaves at the base of large ones will root much better.
2. Use hard green wood or the light brown wood just below it. At least two to three leaves or eyes is best. Cut the leaves back about 2/3 as energy (food) is stored at the base of leaves. If you have a little sooty mold under the leaves (black spot), that means you have a healthy plant with extra sugar (food) to sustain the plant till the roots can form. Just stick it in far enough so that it can stand on it's own.
3. Peat with 40% perlite works well as does any sterile medium that drains well. Just keep it moist and not soaking wet.
4. Bottom heat at a constant 85 is a big plus. Some of the worse bacteria and fungus are more active at lower temperatures. If you cannot spring for a heat mat, try using the top of your frig if the wife or husband will let you. I think the hot water heater has to many pipes in the way. Spring time is great for rooting cuttings but if you have a source of heat, the winter will work just as well. During cooler weather, the top of the plant is more dormant while the heat kicks in the bottom of your cutting with new roots. They just do not need as much energy to survive.
5. Individual or grouped in a larger pot both work. I get pretty much the same % with either method. Individual pots or cells take up more space and you need to watch the watering closer so the smaller cells do not dry out. I have had no problem with putting cuttings all over the larger pot and not just around the edges as was mentioned earlier. The key is all cutting should be the same size which is hard to do. The other key is to put smaller cuttings on the outer edges and taller ones in the middle. If you mix the sizes (length), the taller ones will 'shade out' some of the smaller ones and they will die. One draw back with larger pots is separating all those roots when you are ready to pot them up.
6. Old grafted varieties do not root as well as new ungrafted varieties or seedlings. If you have been experimenting with older varieties with not much luck, it is not your fault. They have picked up tiny viruses from the root stocks that does effect the plants ability to root and sometimes even to bloom as well as it used to.
7. You can use bleach (table spoon to a gallon) or peroxide to greatly improve your take by getting rid of the bacteria and or fungus that kills your cutting.. No bacteria or fungus and it will root. You must use bleach right away because after and hour or two, it has lost all it's punch. Peroxide used at 50% strength can sit on the shelf for several days and also adds oxygen to the medium which roots need. A little drench at least twice a week will help. I have it in my mist system and they get treated every ten minutes all day long.
8. Most will not have a mist system or green house so just keep them in the shade and out of the wind and sun. If all this seems like to much, just stick some cuttings in a pot of whatever, keep it moist and check on it in 4-6 weeks. You will probably have some new plants to enjoy! Good growing to one and all.
Question to Curt from Udi from Illinois:
Now, what do you say about cvs that seem to improve a lot the size and shape of the bloom after grafting?
Curt's reply:
I think it is more the exception then the rule. U may have a seedling or plant that has a poor root system or even just a poor plant (planted in wrong place or in need of some care) that will seem to improve after grafting on the short term. The rest is more perception. Remember, we treat our new grafts like royalty! New potting mix and, in general, great growing conditions and they respond in kind. I have seen no real difference in a rooted or grafted plants grown in the same conditions in the short term. Rooted plants in general do much better in the long run. If your root stock does not grow at the exact same speed as your grafted part, it will slowly create a restriction at the graft and the plant slowly tends to go down hill in the long run. That is one of the reasons so many older varieties that were grafted are now rare and disappearing. They have died off!