This is not posted on our website but I dug it up from the crypt files. I thought it would be interesting for all who love hibbies to read.
Robert
Thoughts on
Own-root Hibiscus Rosa-senensis
By Barry Schlueter
Be advised that my long years of horticulture fun and profit have given me the belief that there are many paths to successful gardening, and many teachers from whom to learn. No two will have the same practices and the only certain way to fail is to learn nothing OR to try and do what EVERY mentor suggests, thereby killing your hibiscus with good intentions and chemical toxicity. More simply, if it ain't broke, don't fix it. My practices are very successful in Webster, Texas, 28 miles from Galveston Bay and one mile from Clear Lake. Your mileage may vary in your microclimate.
Every distinctive new seedling that arrives on a decent plant with reasonably close leaf nodes and attractive foliage and at least some natural branching by first bloom . . each gets assigned a number and working name. From viewing a few thousand of these new seedlings per year, we name and number a few hundred. The rest are discarded or given away. Next we clone each of the keepers, grafting 2 or more of each new one, and we create own-root clones using flats of Oasis #5005 Rootcubes. Ten or so cuttings go into Oasis, and we keep records in our database of the rooting percentage for each named seedling. If no more than 70% of the cuttings root, we eliminate that seedling from commercial consideration (sale to Hines Horticulture, which sells own-root clones of our creations in 47 states.) If the bloom is special but the plant roots poorly, it may be retained for breeding based on some other special qualities like outstanding color, form, size, growth habit or floriferousness. A few that root poorly will be grafted to give to local exhibitors or to friends who graft and sell them locally. We are normally breeders, not vendors.
In general, own-root Hibiscus rosa-sinensis root well, perhaps 80% of them, in our experience. The least successful cultivars on own roots tend to be yellows or the most exotic color blends. Nearly all seedlings with vigorous growth and lots of branching will also root well. Varieties with red or brown stems tend to root especially well. We grow our flats of rooting cuttings in Oasis under about 50% shade and overhead water them from one to three times daily, depending upon how hot it is. Each cutting has two or more tiny leaves near the top, and the bottom end is cut at a slant and dipped in rooting hormone before sticking it in the Oasis. The flat of Oasis must be pre-moistened for success. The callusing of the cut ends occurs within a few weeks, after which nearly no failures will occur, though roots take awhile to emerge from the callus, depending upon the season.
On average we harvest rooted cuttings from the Oasis within 8-12 weeks and pot them into 4" pots of our regular growing medium. After a few months in 4" pots the clones advance to one gallon pots. All hibiscus here are fed Osmocote with trace elements plus Magnesium sulfate, plus gypsum yearly, plus occasional supplements of soluble fertilizers including fish emulsion and Peters 20-10-20 or similar. Once a year we provide each pot with fritted trace elements (STEM.) At least once a year we give each pot an organic treat to feed soil bacteria: fish meal plus alfalfa meal and perhaps cottonseed meal with dolomite to buffer the acidity of the latter. However, very fine hibiscus can be grown using a much simpler regimen, such as a granular hibiscus food applied monthly.
NOTE: for years we added systemic insecticide Marathon to every pot, but now believe that it led to spider mite infestations and required use of Avid and supplemental miticides. We are now determined to use a minimum of poisons in our operation and we no longer use those two products.
Grafted plants tend to bloom sooner than own-root clones, and sometimes the enhanced plumbing of the grafting to rootstock results in larger blooms than on own root clones. Own root clones may take as much as a year longer to make pretty sale plants here, but we find that they are much better branched than grafted clones, are more bushy with closer leaf node spacing, and with more branching, tend to produce many more blooms per season than grafted clones. In addition, own root clones have a relatively unlimited life span compared to grafted clones. They renew themselves from the roots, and even if frost kills the above ground plant, the own root clone can and usually does regrow a new top with great vigor. Understand that we are experienced along the Gulf Coast, not making any hardiness claims more than perhaps 100 miles north of the coast, most winters. Grafted plants, by comparison, are easily killed (at least the exotic grafted top is) by cold weather, and if regrowth occurs it will be the rootstock, usually Pride of Hankins or Albo, not the fancy variety one purchased.
In addition, we find that grafted plants' life spans are limited by the very act of grafting. Eventually senility occurs in the graft zone because there is a limit in the effective plumbing available for good sap flow. Over time, we believe that constriction occurs in the graft zone as old, corky wood applies pressure to the graft zone and squeezes sap flow to the point that flowers get smaller and less satisfactory over time. I happen to be an expert in rose culture, and the attitudes of rose hobbyists are revealing on this issue. Rose exhibitors view the best years for showing flowers from a rose bush to be years four through seven. After seven years many hobbyists will want a newly grafted bush of the exhibition variety in order to continue to have the best possible show flowers of that variety.
As a hibiscus lover and sometime exhibitor, I'd like to regraft my favorite hibiscus at least every five years to have the best possible bloom quality from them. I don't presently have time for that luxury, but when I stop breeding hibiscus commercially for Hines Horticulture, that will be my goal. Those exotics I am able to plant directly in the ground will be on their own roots so as to give relatively permanent plantings.
Wishing you good health and beautiful blooms,
Barry Schlueter
