Hybridizers: It can be fun to breed your own zinnias - Part 3, 1 by Zen_Man

Zen_Man wrote:
EM,

"I wish that would work for Echinaceas."

That technique might work with Echinaceas. I sterilize the cutting in "standard strength" Physan 20 (1½ teaspoons per gallon), and treat the cutting with a rooting hormone (Dip 'n Grow is my favorite because it contains both IBA and NAA and it lets you control its strength by how much you dilute it). The treated cutting is then inserted in a pot containing medium that has been pre-moistened with a dilute solution of nutrients and "half strength" Physan 20 (¾ to ½ teaspoon per gallon). The potted cuttings are placed under a humidity dome to keep the humidity at 100% until the cuttings have time to root (about two weeks). If the dome has vents, make sure they are closed.

The advantage of this method is that the roots grow naturally into the medium in which they will grow, so that you remove rooted plants from under the humidity dome, and they are are already established conveniently in their pots. When those pots become slightly rootbound, I repot them to larger pots. I currently root the cuttings in 3-inch square pots and repot them to 5-inch square pots, which involves minimal disturbance to the roots. I have some 10-inch pots for when the 5-inch pots start to become rootbound.

The 10-inch pots are really too big a step, and I plan to get some pots intermediate in size between the 5-inch pots and the 10-inch pots. The 10-inch pots have been capable of growing some pretty full-sized zinnia plants indoors. I do use plant growth regulators to try to keep the indoor plants from growing too tall.

"The only way I've seen them root from cuttings is in aeroponic cloning devices (EZ Clone or bubbler) of some sort."

Those devices would probably also work with zinnias. But once the roots are formed, there would be the problem of getting them inserted into and arranged within growing medium without injuring the roots.

"If you root cuttings of that particular zinnia, will the blooms look the same or will they be different? I think you had some bloom different after you rooted the cuttings."

Wow! You have been paying attention. Yes, I did have some odd different blooms on some cuttings a couple of years ago. Zinnias sometimes do some crazy things. I have also had zinnia plants that had significantly different flowers on different branches of the same plant. But, yes, it seems that the stress of becoming reborn as a new plant from a cutting has on occasion produced some odd results. However, in general, the clones are pretty much identical. For example, all of the zinnias in the attached picture were cuttings from the same purple scabiosa flowered zinnia, and they seemed to be pretty much identical.

ZM (not associated with any product or vendor mentioned)