Hi Jessica: I saw your garden posted in Rose Gallery, very nice !! So glad to have another sticky-alkaline-clay gardener to compare notes with.

Potassium leaches out more in clay soil, see this abstract: http://onlinelibrary.wiley.com/doi/10.1111/j.1475-2743.2004.tb00355.x/abstract

"A set of lysimeter based experiments was carried out during 2000/01 to evaluate the impact of soil type and grassland management on potassium (K) leaching. The effects of (1) four soil textures (sand, loam, loam over chalk and clay) ... K applied as inorganic fertilizer, dairy slurry or a mixture of both sources were tested. Total K losses in the clay soil were more than twice those in the sand soil (13 and 6 kg K ha−1, respectively)."

The research done by Cornell University stated that in sandy soil, calcium and magnesium leaching is a problem. But in rainy weather, potassium leaching is most severe.

The link below by University of Wisconsin-Madison contradicted with the abstract, by stating that potassium-leaching is worse in sandy soil, compared to clay soil. The researchers also noted that potassium is best in readily available form, via SOLUBLE. They also noted that the amount of potassium in a plant decreases as it matures, thus the need for more potassium as the plant gets larger.

Thanks to Sharon asking me questions in the thread "Where do I start?", I researched on the ratios of fertilizers to use: It's equal ratio of potassium to nitrogen. Since blood meal has NPK 12-0-0, and sulfate of potash has NPK 0-0-50, if you multiply 12 by 4, you'll get 48, that's almost 50. So it's 4 times more blood meal than sulfate of potash. If you give your roses 1 teaspoon of sulfate of potash, you would need 4 teaspoons of blood meal for best growth. But that depends on the rose, if it's a too-many-leaves, too-big, then twice more blood meal than sulfate of potash is enough.

For potassium, calcium, and magnesium ... it's 4:2:1 ratio. Which means twice more potassium than calcium is recommended. My alkaline clay have plenty of magnesium & tested by EarthCo. to be exceedingly high in magnesium, but deficient in potassium. Magnesium is what makes clay soil sticky like mud.

The above ratio of 4:2:1 for potassium:calcium:magnesium is established in a hydroponics setting. For potassium to phosphorus, the ratio of 2:1, and 4:1 are recommended by Purdue University, even on severely phosphorus-deficient soil.

But the above ratios vary with the type of roses: Some Old Garden roses produce nothing but leaves, like my Le Rire Nias and Jacques Cartier ... these need more potassium & phosphorus than nitrogen to promote blooming.

My Pat Austin is own-root, it had droopy neck for 3 years, until this 4th year, I gave it sulfate of potash and chicken manure. Since I already put down 2 applications of chicken manure (high in nitrogen), I gave it 2 watering of SOLUBLE sulfate of potash, at 1 teas. per 1 gallon of water. This year the stem are thicker, and no more droopy necks, even after 3-days of heavy rain, see picture below:

Here is a link that might be useful: Soil and applied potassium by U of Wisconsin