Crown your Roses to beat Black Spot

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

Good mulch brings good bugs

Leaves under butternut squash and tomatoes

A gentleman of my acquaintance asked me what to do about squash bugs.  I said that I never really have a problem with squash bugs.  Turns out that the people he is helping with their farm are using plastic mulch to control weeds and row covers to try to control insect pests. 

I pointed out that what controls bad bugs are good bugs, predators that eat the plant eaters, and the most effective ones require good mulch like leaves to live under.  When you have plastic mulch or bare soil, you lose all the spiders, centipedes, ground beetles, and soldier beetles, to name a few of the most effective predators in the garden.

Warming rocks under peppers.  They warm the soil at night, cool it during the day.

Almost all of these predators live exclusively under loose mulch and rocks.  Soldier beetles spend the spring month of their adult lives flying, eating aphids, mating, and laying their eggs under mulch, where their larvae live under the mulch the remaining 11 months of the year, eating anything they can catch and kill.  If you have no loose organic mulch, you will have no soldier beetles laying eggs, and few or none of the others.

He said that the plastic mulch is needed to keep weeds down.  I said that leaves do that.  Not only do they keep sun off the seeds that need light to sprout, but they are a poor sprouting surface, as they dry out quickly, so seeds that land on top cannot sprout either.  Only larger seeds can get through 2 inches of leaves, and they are easily pulled; it is the tiny seeds that need sunlight on soil that are hardest to control without mulch.

4x8 sand and rocks under peppers and melons.  Insects are not under sand, only under rocks.  Sand is too hot.  Walk-on fir bark is beyond.

Plastic mulch cannot feed soil, while leaves are the natural food of worms and other detritus eaters, who turn them into soil.  One eater of detritus is the earwig, which many think of as a pest.  They are rather creepy in their habit of hiding in flowers and foliage during the day and coming out when they are brought into the house, but they don’t generally eat live plants; they eat the fungus out of dead or living leaves and can actually eat fungus, like rust on hollyhocks, out of your plants. 

Wikipedia considers earwigs omnivorous and says that they eat insects and plants.  Scientists seem to have missed that they love the fungus-infected parts of leaves.  They are said to eat corn silks as well, but I always have many earwigs and no corn silk damage.  Without fungus-ridden rotting leaves to eat, earwigs have only the softer parts of live plants to eat.

Two inches of leaves is great for stopping weeds and feeding soil.  12 inches or more can make wonderful soil and grow huge plants as they decompose.  Start next year’s garden by gathering your leaves this fall, rather than giving them to the trash company for compost.  They will make wonderful compost in your garden if you just let them lie there, and add to them.