In conjunction with research I began in 1968 on the feasibility of growing grass sods over plastic sheeting using contrived media, it occurred to me that it might be possible to design a method by which ground covers could also be grown as sods like turfgrasses. By ground covers I mean plants such as Ivy, Ajuga, Pachysandra, Euonymous, Vinca, and many other usually low growing, dicot creepers or spreaders that are used frequently in place of grasses, particularly in shady areas, by landscapers. I mentioned this idea in a 1975 article I wrote for the trade magazine "Weeds, Trees, and Turf".
It can easily be surmised that ground covers will root sufficiently to form and bind into a sod by simply observing the plastic flats filled with ground covers in a retail nursery. Ivy and Pachysandra, for example, are frequently sold in small plastic trays or flats containing a suitable growing medium into which 6 or more cuttings have been inserted or stuck. If these cuttings are cared for yet left long enough in the plastic trays without being sold, it can be shown readily that they will knit into a sod: one can remove from the plastic flats all of the cuttings, roots intertwined with the growing medium, in one piece--hence a sod.
The rooting capacity of Ivy was further confirmed by a student of mine who subsequently used the project to obtain an M.S. degree in Horticulture at Ohio State University. Cuttings of Ivy were simply stuck into wooden flats containing appropriate growing media placed over plastic sheeting, that is, essentially the same as growing it in plastic trays or flats. These were maintained under mist conditions in a greenhouse and after several weeks the cuttings, as expected just as in plastic trays in a retail nursery, rooted sufficiently to bind and knit the flat into a sod. Because of the extensive hand labor involved in sticking the cuttings, the repeated cost of the cuttings, and the special greenhouse conditions required, there was no commercial significance to these observations, that is no economic advantage over the conventional landscape system of establishing ground cover beds from rooted cuttings. For the grower it was much more profitable, given the premium of greenhouse space, to sell individual rooted cuttings rather than to wait for the cuttings in a plastic flat to mature into a knitted sod.
It occurred to me however that perhaps a novel growing system could be devised to minimize or to eliminate altogether the extensive hand labor, the repeated cost of cuttings, and the expense of greenhouse culture, and yet still produce a ground cover sod of commercial significance.
Many techniques were considered and tried and found unsuccessful until I conceived a novel, workable, process, described below, which I demonstrated in a series of experiments on my farm in Ostrander, Ohio. The results of the 1978 experiments were submitted as a Document Disclosure to the Patent Office and dated 8 Feb., 1979; and I further supported, expanded, and refined my novel growing process during the 1979 and 1980 growing seasons.