Betty Boop, October 2014, after being crowned in the spring. Note the black spot starting at the base. This rose is nearly thornless on young parts and blooms all summer into late fall.
When roses are starting to break bud and grow leaves, it is time to crown
them, to stop black spot fungus from taking them over and making them pretty
flowers on an ugly bush. The spots are
on the stems, and they infect the leaves after they mature. Removing all the stems, down to the crown,
the hard knot of wood from which both roots and stems grow, takes all the
fungus off the plant and stops black spot from showing up until fall.
2016 Betty Boop rose, ready to crown. Note the purple new growth. It never quite stopped growing this winter.
You do not want to crown them in late fall or in winter
before bud break, or they won’t grow until months later, as they then feel only
the temperature of the soil, and wait until the soil warms up, much later than
the air does. Once they begin to grow leaves, the plant is already growing and cannot stop; it will grow new stems very quickly, though they will bloom no sooner than if you did not cut
them.
Betty Boop rose buds breaking red, ready to crown. Notice the black spots starting.
Some roses bud green. The black spot fungus grows and spreads all winter.
Nearly all tea roses get black spot in this area, as our
winters are not cold enough to kill the leaves or even stop blooming. The way we were taught to prune roses in spring
in Landscape Management class was to wait until the photinia bloomed, to
prevent freezing of tender new growth, and cut them down only to a foot tall,
cleaning out spindly growth on what is left.
But I found that black spot took over the plant before it even bloomed,
as soon as the new leaves were mature. And roses start breaking bud before the
photinia blooms, earlier in recent years, so leaf growth before that point was
wasted, and blooming was delayed.
Betty Boop, cut the classic way roses are normally pruned in spring.
Our teacher taught us that the way to bring any old, ugly
shrub back to youth and beauty is to cut it to the ground. When I applied this to roses, I found that it
works for them, too; it grows back beautiful, with no black spot and great
blooms.
Betty Boop, crowned for the third year. It was about 10 years old before the first crowning, a large, upright shrub rose; trunks 2-3 inches across, the whole crown about 8".
But cutting to the ground is not far enough if the crown is
buried. If you stop at ground level and
don’t cut back to the crown, the underground stubs will grow small stems that only crowd the bottom of the plant. You have to dig down to and around the crown
and cut flush with it, filling back in afterwards. Stems that grow directly from the crown grow
back thicker and longer than from stubs, often to their maximum height for that
kind of rose.
If that maximum height is too tall for your taste, you can
crown it again after the first flush of flowers and it will grow back half as
tall and bloom again. One can crown a
rose anytime during spring or summer and may want to if it grows mold on new
growth. But crowning in fall can cause
new growth to freeze while it’s still tender and might kill it.
Revised 12-10-24, published online at GardenGrantsPass.blogspot.com
Gardening
is easy if you do it naturally. Litter
is tagging, marking the territory of the disorderly.
Rycke Brown, Natural Gardener 541-955-9040 rycke@gardener.com