I bought plenty of own-roots from Heirloom nursery. They come in TINY band-size, took months to nurse them in pots, so they can be planted in the ground. All them died in 1st winter, except for 2 vigorous old-garden roses. Old-garden roses are vigorous to withstand actual environment of drought, flood, heat, cold, and pests in the ground.

Except for some VERY VIGOROUS hybrid-teas, most modern-hybrid-tea are better as GRAFTED to bridge the difference between soil/climate where they are bred, and the soil/climate of the purchaser. The problem with roses like Kordes that are bred in Germany? Consider that climate (from internet): "The climate in Germany is temperate and marine; cool, cloudy, wet winters and summers." Consider actual climate in regions of America: hot summers up to 90 to 100 F, and weeks of no rain.

I choose roses a shade darker than desired, for the reason that cool/temperate weather makes rose deeper color, but the same roses will be completely faded in hot & sunny weather. Also alkaline-tap water fade roses horribly, but acidic rain break down the trace elements in soil, to make blooms deeper in color. Abraham Darby can be gorgeous deep pink in cool/wet climate, but it's ugly beige in hot sun, or watered with alkaline tap water. Municipals put hydrated lime in tap-water to protect pipes from corrosion, and that zap out the deep & vibrant colors in roses. Horse manure with trace elements deepen the colors, but it's a real pain to get horse manure, even when it's less than 5 min. drive.

I spend $$$ to buy lots of SOLUBLE fertilizer to nurse these wimpy own-roots in pots so they can be big enough to planted into the ground. But they never can reach the woody-status of Dr.Huey-rootstock, nor the depth of Dr.Huey-rootstock to withstand drought. It's easier to choose VIGOROUS own-roots that are suitable for one's soil and climate, than nursing UNSUITABLE tiny-own-roots into big size in pots. And even when they get big, they will be diseased if the conditions are not the same as where they are bred: temperate and wet like Germany, England, or Oregon.

So many California folks complain about own-root Kordes being stingy and not blooming. Why? To stay healthy in a wet/temperate climate like Germany, there are 2 ways: 1) breed for vigor, and that's what you want, vigorous root that can be planted as own-root, deep-root that can go for months with no rain 2) or breed so that roots secrete less acid, to protect leaves from fungal infection. The problem with roots secreting less acid? It will be stingy and no blooms in regions with less acidic rain to break down hard minerals in soil.