One of the benefits of being chair of our Chapter plant sales is that sometimes I know in advance what people are bringing. I talked with a member today, and she is bringing some Epimedium cantabrigiense. But I don't have room in my garden if it runs too much. How does it compare with Orangekönigin (which I have), regarding this quality?
An excellent topic Rick, one that should always be considered when choosing and planting Epimedium. Basically there are two types, those that run (be careful, some can romp and invade other plants), and fortunately the majority of epimedium are clumpers. In both categories, it is good to be aware of the degree of spread in a certain number of years. The Garden Vision Epimediums nursery is quite useful (and rare) in supplying the average annual spread for any species/cultivar that runs. A few are lacking that info.
I do not grow the type E. x cantabrigiense with salmon orange sepals, but do grow
E. x cantabrigiense "Red Form" with red sepals, and yellow petals, that more closely resemble the first parent (E.alpinum x E.pubigerum). This is an interesting combo, as a romping spreader with tiny flowers (
E. alpinum) is crossed with an evergreen clumper (
E. pubigerum), possibly "tamed" by the E. pubigerum influence. The "Red Form" is a sweet little thing, tending not to spread at all... but the caveat is, it was growing under Stewartia pseudocamelia, with surface roots so dense that almost nothing grows under this fine tree. I show a photo where I moved the plant to a new area, a cutie in flower, but I can't give defacto experience in the running habit at this point.
E. x warleyense is a slow-to-moderate spreader (also sterile), but a strong and determined "tight spreader". In 10 years it might be 3' (1 meter) across. The cultivar
E. x warleyense 'Orangekonigin' is a very fine plant, but here again, I salvaged the plant from the dense roots of Stewartia, where it was surely terribly constrained by root competition, and I recently gave it free reign in a new location where it'll hopefully be more plentiful with its fertile orange flowers... I anticipate it'll be a slow but strong spreader much like regular E. x warleyense.
So, I haven't really answered your question, but in terms of the "Red Form" of E. x cantabrigiense, it seems well-behaved, although you may need to ask me again next year. Other running Epimedium, I have already relegated to wilder parts of the garden where they are allowed to romp; this includes one of the parents of E. x cantabrigiense;
E. alpinum, which Darrell says spreads 12" (30 cm) in each direction each year, and
E. alpinum 'Shrimp Girl', a miniature form that is much shorter and supposedly has shorter rhizomes that spread 4-5" (10-12.5 cm) a year, but I find it spreads much faster... easily at the 12" pace. Epimedium alpinum should be treated like Vinca, or Pachysandra, only in areas where they can spread into large colonies as a groundcover, suitable for covering many square yards under a dry steep wooded area as an example. But possibly
E. x cantabrigiense is tamed by the excellent behavior of
E. pubigerum... that's my guess, thus more suitable for better company in the garden.
