There’s nothing quite so lovely in a summer garden than a rosebush in full bloom. Roses are truly the quintessential flower. With their characteristic unfurling bud and timeless scent, you’d be hard-pressed to find a bloom more beloved the world over.
As is often the case with something so delicate and beautiful, cultivating roses comes with its own set of challenges.
From pests to diseases and environmental stress, it can feel as though Mother Nature is out to get your roses. Each of these problems can have a major impact on the health of your plants, leaving you with few to no blooms or, worse, a dead plant.
But as they say, knowing is half the battle, which is why we’re going to take a look at the most common rose-growing problems you’re likely to encounter. We’ll look at how to identify and treat each issue. Hopefully, knowing what to look for before it reaches your rose bushes will help you maintain gorgeous, thriving roses covered in blooms each year.
Powdery Mildew
Powdery mildew is by far the most common affliction roses face each year. This airborne fungus affects many other plants and flowers, as anyone who’s been gardening for a few years can tell you. Thankfully, our southern gardening expert, Fawn, has figured out how to deal with it. (We’ll get to her method shortly.)
Symptoms:
Powdery mildew appears as white powder or grayish blotches on the leaves, stems, and buds of roses. Once infected, leaves may curl up or drop prematurely. You’ll likely notice it begin to show up during periods of hot, humid, rainy weather.
Treatment:
First, prune off as many of the affected parts of the rose bush as possible. While you’re pruning, you may want to make some thinning cuts to improve air circulation within the plant and around the bottom of the plant. This is especially important if you have rose bushes growing close to one another. If need be, prune them to open a bit more space between the plants.
Finally, use Fawn’s powdery mildew go-to, hydrogen peroxide, to rid your roses of this fungal menace. Skip all the other home remedies out there and start with her method first. You won’t be sorry. You can read how she mixes it and when and how to apply it here:
My Foolproof Powdery Mildew Remedy That Works In Two Weeks
Black Spot
Another fungal disease, black spot, is quite common during periods of warm, rainy days. (Have you noticed a trend?) Much like powdery mildew, black spot is unsightly but usually won’t kill your rose bush. However, the stress of the infection weakens the plant, making it more susceptible to other pest and disease damage.
Symptoms:
The name says it all, black spot shows up as small dark brown or black spots covering the leaves and sometimes the stems of your rose bushes. Left untreated, it can cause the leaves to yellow and drop off. Again, rarely will black spot kill your plant, but it significantly weakens the shrub, opening it up to other issues.
Treatment:
The treatment for black spot is the same as for powdery mildew. You’ll want to remove affected portions of the plant and prune to open it up more. Again, Fawn’s hydrogen peroxide solution is highly effective in eliminating black spot from your roses and is much less harsh than a commercial fungicide.
Aphids
If you grow roses for any length of time, eventually, you’ll deal with these annoying little bugs. If left unchecked and the infestation is bad enough, they can kill off a rose bush.
This is especially true for new plantings that aren’t established yet.
Symptoms:
Aphids are tiny green, pear-shaped insects that hang out on new growth, buds, and the undersides of leaves. They suck plant sap, causing distorted growth and yellowing leaves.
You’ll often see the evidence that aphids were there before you notice the insects themselves. Shiny, sticky dots on leaves are a hallmark of aphids. They produce a sticky substance known as honeydew. Ants, which feed off the honeydew, on your roses is another sign you may have an aphid infestation. Finally, you can often find their shed exoskeletons stuck to the honeydew on the plant. It looks like fine, white sand or dust has been sprinkled on the plant.
Treatment:
Lindsay has more to say on these little green pests here, including ten different ways to get rid of them. However, the easiest way to keep aphids in check is also the simplest – spray them with water. Use a garden hose with an adjustable nozzle that will allow you to spray your rose bushes with a powerful blast of water.
Unfortunately, this method requires repeat spraying to keep the aphids under control, which is why Lindsay offers more than one method of control, including encouraging some of their natural predators to hang out in your garden.
Spider Mites
These pests are a thorn in any rose grower’s side, whether you grow your roses indoors or out. Luckily, they’re pretty easy to get rid of.
Symptoms:
You’ll often notice splotchy yellow-green leaves. Upon closer inspection, it will appear as though the leaves have yellow stippling or pinpricks all over them. Look in the space where the leaflet meets the stem, and you’ll likely see a web of incredibly fine webbing. Spider mites thrive in dry, dusty conditions. (You can’t seem to win with the weather and roses!)
Treatment:
Just like with aphids, the easiest treatment for spider mites is to spray the plant with water. Again, use a garden hose with a powerful spray nozzle to blast the little buggers out of your roses. Don’t stop there. However, you may want to mist your roses occasionally if the weather continues to remain dry, as the extra moisture can prevent spider mites from returning. Neem oil spray or an insecticidal soap made by mixing a couple of drops of liquid dish detergent with water are also great ways of ridding your roses of spider mites.
If you’re growing roses indoors, consider adding a pebble tray or a small humidifier to raise the humidity near your roses.
Rose Rosette Disease
This funny-sounding disease is only found in North America. (For now.) However, despite its name, rose rosette disease is no laughing matter. Discovered back in the 40s, it has slowly spread throughout the states and into Canada. It only affects roses, but it is devastating when it does.
Symptoms:
Rose rosette disease, or RRD, causes abnormal growth, including witches’ broom-like clusters of shoots, bright red discoloration of leaves that don’t turn green, and distorted flowers. You’ll likely notice an excess of thorns as well. It is spread by eriophyid mites.
Treatment:
Unfortunately, there is no treatment, and once infected, roses with RRD need to be removed and destroyed to prevent the spread of the mite and the virus it carries. Dig up the plant, including the roots and surrounding soil and burn or put it in the garbage. Under no circumstances should it be composted.
Rust
Oh, look, another fungus that affects roses. I think it’s safe to say that roses do not do well in damp weather. This is one of the reasons why it’s so important that they be planted in a space where they receive plenty of sunlight.
Symptoms:
Rust appears as orange or rusty brown spots on the undersides of leaves and sometimes on stems. It weakens the plant, making it more susceptible to other diseases and pest damage and can lead to fewer blooms.
Treatment:
You probably already know what I’m going to say here, so I won’t repeat myself. If you need a refresher, see the treatment for both powdery mildew and black spot.
Thrips
Another insect that loves to feast on your beautiful rose blooms are thrips. And like aphids and spider mites, they can find your roses both inside your home and outdoors.
Symptoms:
Thrips are tiny, slender insects that feed on rose buds and flowers. Once the thrips have fed on the bud, it may not open at all, or if it does, the resulting flowers can be discolored or oddly streaked.
Treatment:
Prune and dispose: As soon as you notice thrips or evidence of their damage, remove infested buds and flowers and dispose of them.
Apply insecticidal soap (again, the best insecticidal soap is often the simplest, a couple of drops of liquid dish detergent mixed with water) or neem oil: These products can help control thrip populations.
Encourage natural predators: Introduce beneficial insects like predatory mites or minute pirate bugs.
Rose Bush Not Flowering
This one is a bit tougher to diagnose, as it can be caused by any number of issues or a combination of them. The most likely causes, however, are not enough sunlight, pruning issues, nutrient deficiencies or stress from pests or disease.
Symptoms:
Well, this one is kind of obvious.
Treatment:
Pruning: Properly prune in the late winter or early spring to encourage healthy growth and flowering. During the blooming period, deadhead roses often stimulate new growth and more blooms.
Fertilize: Apply a balanced fertilizer formulated for roses in spring and after the first bloom cycle.
Ensure adequate sunlight: Roses generally require at least 6 hours of direct sunlight daily for optimal flowering. If your bushes are in a spot that isn’t getting enough light, you may need to wait for them to go dormant and move them.
Winter Damage
Depending on where you live, severe winter weather and freezing temperatures can cause damage to your rose bushes that show up the following spring. While there isn’t a whole lot you can do after the fact, there are steps you can take to prevent your roses from sustaining damage during the colder off-season.
Symptoms:
Winter damage often shows up the following spring when portions of the plant die back or show cracks in the canes from frost.
Treatment:
Prevention, prevention, prevention. If you live in a growing zone with cold weather, protect your roses in the fall by applying mounding soil around the crown of the plant. Then, apply a thick layer of mulch around the base of your roses. This will protect the roots from freezing. You may also wish to wrap the plants in burlap to shield them from heavy winds.
Prune roses in late winter to remove winter or cold-damaged canes and to encourage new growth and blooming. Cheryl can walk you through late winter rose pruning here.
Nutrient Deficiencies
Roses are heavy feeders. They need plenty of the right nutrients to provide blooms throughout the growing season continuously. If you aren’t replacing lost nutrients each year, you can quickly run into problems with your plants. Different nutrient deficiencies show up with different symptoms.
It’s generally good gardening wisdom to test your soil, especially if you aren’t actively adding compost or other organic matter to the soil each year.
Symptoms:
- Nitrogen deficiency: Pale green or yellow leaves, stunted growth.
- Phosphorus deficiency: Poor root development, dark green or purple tinted leaves.
- Potassium deficiency: Weak stems, yellowing and curling leaf margins.
Treatment:
Fertilize: Apply an organic balanced fertilizer with micronutrients, adjusting based on soil test results.
Organic matter: Add compost, leaf mold, well-rotted manure and other organic matter each year. As it slowly breaks down, it will improve the soil. You may also want to try inoculating your plant with mycorrhizae. These beneficial microbes can make nutrients in the soil more readily available to the rose bushes.
Foliar feeding: Some liquid fertilizers can be applied directly to the leaves for quick nutrient uptake. However, some nutrients are more readily absorbed through the leaves than others. Lindsay has everything you need to know about foliar feeding, separating the fact from the fiction.
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