It is silly to be infatuated by potting soil, but we are. Thanks to Dave Andrews and the magicians at Pro-Gro Mixes & Materials, FRCC now has eight yards of our custom blended potting soil, perfect for clematis in containers. When the collection was housed at Gutmann Nurseries, the generous Bob Gutmann allowed Brewster and his volunteers to experiment with soil blends, using raw materials the nursery kept on hand.
Brewster suggested we blend our own mix after getting a shipment of happy little clematis plants from LaPorte Avenue Nursery in Ft. Collins, CO. The plants, mostly Colorado natives, arrived in a gritty soil with amazingly well developed root systems. It occurred to Brewster that most clematis would enjoy a coarser soil mix, and that such a mix might hold up better than regular potting soil, which starts to degrade and acidify, becoming “wet chocolate cake”, after only a year or two.
Gutmann’s basic potting soil from Pro-Gro is the #9B blend, containing some bark, pumice and a touch of peat moss. Our favorite blend (pretty much perfected by volunteers Rick Meigs and Sharon Kaito) starts with 50% Pro-Gro #9B, to which we add: 25% pumice (chunks the size of kitty litter), 15% coir fiber (coconut fiber), and 10% washed sand. The resulting alchemy is gritty and sturdy, not light and fluffy, and if I were clematis roots, I would love winding my way through it. Imagine stretching and having your back scratched at the same time, while being comfortably moist but not drowning. Mmmm…
FRCC now uses this soil blend for all of our potted clematis, including those we sell. We have also started using this soil in our “weaning” blend, the soil that newly rooted cuttings are moved into when they come off the perlite. Our weaning blend is now 33% coir fiber, 33% perlite, and 33% our potting soil. This is topped with 1/4 inch of #2 poultry grit, to keep the soil surface clean and move water away from developing crowns. (Don’t use the finest, #1 grit, as it has fine particles that can form a crust on the soil surface.)
If you have a nursery in the Willamette Valley or SW Washington, and need custom blended soils, let us recommend the folks at Pro-Gro. And if you need a lot of good soil for growing clematis in containers, just call ‘em up and ask for the Rogerson Clematis Collection mix. Visit their website,
www.pro-gromixes.com for more information.