9 Reasons Roses Drop Their Flowers
Is your rose losing its blooms this season? There are a few causes for flower drop in roses. In this article, expert gardener and rose enthusiast Danielle Sherwood explains the most common reasons your rose might be dropping flowers, along with how to combat the cause!
If you’ve been anticipating beautiful spring flowers, seeing new buds and blooms drop from your rose bush is a major disappointment. While this happens for a variety of reasons, there are some clues you can use to narrow down the cause.
Identify the root of the problem so you can tackle it. Your rose might be a victim of pests, disease, weather fluctuations, lack of nutrients, or a recent move. Once the problem is identified, you can begin taking steps to bring back the blooms!
In this article, I’ll outline the most common causes of bloom and bud drop (called Bud Blast) and give pointers for bringing your rose back to its healthy self. Let’s get started!
Most modern roses produce multiple bloom flushes in 6-8 week cycles throughout the season. Starting in spring, your rose will burst into blooms that last 2-3 weeks on average.
As the first flush of flowers gradually fades, the petals will wither and drop from the bush. This is a natural cycle and nothing is wrong with the rose. After blooms are spent, the plant needs a bit of time to rest and refocus its energy to produce the next bloom cycle.
You can trigger new growth and tidy up your rose bush by removing spent blooms, a process called deadheading. In fact, unless you’ve planted a self-cleaning variety, deadheading is crucial.
Removing spent blooms tells your rose it’s time to work on producing the next bloom cycle. If flowers are left to drop on their own, the rose bush will think it’s time to work on the production of seed-bearing hips. Once hips appear, the plant is unlikely to bloom again that season.
Some Old Garden and rambling roses bloom only once per season in the spring. They usually flower for a longer period of 4-6 weeks rather than in multiple short flushes. If you’ve deadheaded and no blooms return, you may have one of these varieties.
Blooms have been present on the bush for 2 weeks or more and are beginning to lose petals and wither.
This is part of the rose’s lifecycle and completely natural.
Deadhead spent roses (snip off the stem just above a leaf node) to trigger new growth and more blooms. In addition to keeping things tidier, this tells your rose it’s not yet time to produce hips and enter dormancy, concentrating its energy for the next cycle of flowers.
Botrytis blight can cause blooms with brown speckles or larger blotches. Some buds may develop abnormally, withering and dropping from the bush.
The fungus behind blight, Botrytis cinerea, is most likely to appear during the mild temperatures and rainy conditions of spring or fall.
While some buds will drop, others will get brown and mushy. They remain on the plant but never fully open.
Botrytis blight likes to enter rose canes in spots where they’ve been previously wounded by pests, mechanical damage, or extreme weather. It then causes infectious cankers that slowly spread.
To prevent the spread of botrytis blight, good sanitation is key. Always sanitize your pruners between plants (I like to use a jar of rubbing alcohol to dip them in for this purpose). If you see a suspected infection, prune it out and dispose of it.
Check rose petals for softened brown patches or tan dots. Inspect canes for lesions (cankers) where the fungus has entered the site of prior injury. As infected plant material decomposes, it may become covered by a wooly gray coating.
Thoroughly sanitize your pruning shears to prevent inadvertently spreading the fungus. To mitigate wet and humid conditions, plant roses in full sun, water in the morning to let foliage dry during the day, and apply good pruning practices to maintain good airflow.
Monitor plants frequently during rainy weather. Prune off affected flowers, leaves, and canes to prevent spread. This is often enough to stop further infection. Botrytis blight is resistant to fungicides.
Like botrytis blight, balling is most likely to occur during the rainy season. Buds begin normal development, but excess moisture saturates the outer petals, causing them to fuse together and become dry and crispy.
Certain varieties are more prone to balling in the rain. Deep cupped and globular blooms (like those of many popular English roses) are most likely to ball. The affected buds can sometimes be salvaged. Other times they fall off the plant or develop mold.
After lots of rain (or intense overhead watering), the outer petals of the bud may look browned, crispy, or even feel a bit slimy. Buds will not open. If left on the bush, they can develop mold and rot.
If you have susceptible varieties with large, double blooms, consider providing some shelter from heavy rains with a tarp or propped umbrella. Plant roses in full sun where they’re likely to dry out quickly. Make sure you prune and space roses for adequate airflow.
See if affected buds are salvageable by gently prizing apart the brown outer petals. If it looks normal inside, removal of the outer petals may allow it to bloom. If the whole bud appears compromised, remove it before it develops mold that could spread to the rest of the plant.
The pesky Merhynchites bicolor, commonly called the rose curculio or rose weevil, is a small (quarter-inch long) beetle that targets pale-colored roses, especially yellow rose varieties and white rose varieties.
Roses plagued by curculios might have stems that are broken right under the bud, leading to dropped blooms. Roses that remain may have holes in the petals. Damage is caused by the adult weevils, who puncture buds and lay their eggs inside, as well as the larvae who chew petals once hatched.
Rose curculios have a pretty predictable life cycle that makes control simple. If they are left to feed and reproduce freely, they can cause significant damage.
Watch for weevils in April or May, when they emerge from the soil and climb rose canes to feed on new buds and flowers. They are shiny crimson and black, with long snouts. Total size is about ¼ inch. If bud stems are broken and petals have holes in them, look closely for the presence of small white larvae.
Rose weevils overwinter in the dirt and can be controlled via the use of beneficial nematodes that you can water into the soil surrounding your rose bush. If you create a biodiverse garden by surrounding your rose with companion plants, natural predators like wrens and warblers will be attracted to your yard and eat larvae and adults.
Badly-infested buds that remain on the bush should be snipped off and thrown away. Shake visible adults into a jar of soapy water, which kills them. Avoid the use of insecticides. They are often ineffective, require repeat applications, and harm natural predators and beneficial insects.
If you see colonies of visible bugs clustering around a tender new rosebud, you’re probably dealing with aphids. Frequently the first pest to show up in early spring, aphids feed on roses by using piercing mouthparts to suck out the sugary juices.
Fortunately, aphids are soft-bodied slow movers that make easy pickings for predators (and us!). They are also easy to spot. Pear-shaped and light green, you will see them huddled together on new growth and buds.
While you’re likely to see the aphids themselves, you might also notice their damage: distorted buds and curled leaves. There is sometimes a sticky, black substance called Sooty Mold that grows atop the honeydew aphids secrete onto the rose leaves.
Look for clusters of tiny (⅛ inch or less) light green, pear-shaped insects crawling on the new shoots and buds of your rose. You might also see deformed buds, curled leaves, and sooty mold.
If your garden is welcoming to natural predators, aphids are unlikely to last more than a couple of weeks. They are a favorite snack of birds, ladybugs, hoverflies, and lacewings.rnrnEncourage them to show up by making your garden welcoming with lots of companion plants, preferably native. You can also mask the smell of your roses or repel the pests by interplanting with rosemary, catnip, marigolds, and alliums.
Getting rid of aphids is easy. Aim at them with a strong, direct spray from your hose. This will knock them to the ground where they’re unlikely to crawl back up. If they appear in extreme numbers, an insecticidal soap may be helpful (always use with caution and apply in the evening to reduce harm to beneficial bugs).
Thrips are so small (less than 1 mm) that you won’t see them unless you’re really looking. The damage is often noticed first. Common indicators are wilted blooms with brown flecks and streaks, or petals edged in brown. Darkened buds that never open and fall from the plant occur when the problem is advanced.
If you suspect thrips, gently pull apart an open bloom to peek inside. If you see tiny rapidly moving insects at the interior base of the petals, they’re probably your culprit.
Thrips weaken roses by extracting sap from foliage and flowers. They most commonly attack light-colored roses.
Thrips burrow deep inside rosebuds and blooms. You’ll need to check for them moving at the base of interior petals if you see symptoms like brown-edged petals, streaks, and spots.
Keep the area immediately surrounding your roses free of their preferred habitat: long grass and weeds. Use blue sticky traps to lure them away from roses.
Removal of infested buds often takes care of the problem. Prune them off and throw them out. If further action becomes necessary, try a fungus-based insecticide. Consider releasing natural predators like pirate bugs and lacewings, and prevent future outbreaks by making your garden attractive to them in the long term with a diversity of plants.
Roses are sensitive to severe temperature fluctuations. If a late frost strikes after buds have appeared in spring, the new growth may die back (i.e. turn black, shrivel, or drop).
Dieback can also occur if the fragile new growth triggered by pruning is exposed to major temperature fluctuations in spring or fall. Prune when dormant, or when the danger of frost has passed.
Dieback can cause young shoots and canes to darken and become weak. Sometimes the site of injury provides a place for fungal infections to strike.
After a frost, new buds and young shoots may shrivel and turn black and fall from the plant. Look for damage at the tips of canes.
Don’t prune your rose in spring until 6-8 weeks after your last frost date. Apply the same rule in reverse to fall. Stop deadheading and pruning 6-8 weeks prior to the first frost to cue your rose to produce hips and go dormant for winter. If your rose has recently produced new growth, keep an eye out for frosts and provide winter protection as needed. Always plant cold hardy varieties appropriate for your growing zone.
Cut off and dispose of any damaged buds and canes, trimming them down to where you see healthy green growth. As long as the crown (or bud union in grafted roses) is healthy, your rose will soon sprout again.
Drought and heat stress
Just like cold winds and frost can damage roses, stress from drought and heat take their toll as well. Roses suffering from consistently dry soil and intense summer rays can wilt, have scorched brown leaves and petals, and drop buds.
Roses like warmth and sun, but they experience stress when temps rise above 85 degrees Fahrenheit. In fact, in extreme heat or drought, they may enter a sort of dormancy, focusing on survival rather than new growth and flowering.
Above 95 degrees, essential processes like transpiration and photosynthesis are compromised. Fortunately, you can ease the stress on your rose with some key practices, including starting with roses recommended for high drought tolerance and hot temps.
Roses may have brown and scorched yellow leaves. Whole plants may be wilted or dry. Test for soil moisture by inserting your finger deep into the soil. If it feels dry at knuckle level, it needs water.
Mulch heavily to keep roots cool and retain soil moisture. Up water intake when soil is dry at knuckle deep, and always aim irrigation at the soil level where it’s most needed rather than overhead.rnrnOn particularly hot sunny afternoons, move potted roses to a shaded area and consider placing them in a larger container filled with water, letting the roots absorb it fully from the bottom. Use a shade cloth or temporary screen for roses in the ground.
Drought and warmer summers are changing gardening for many of us. While you can’t remove the problem, you can conserve water if you reduce your lawn size and install drip irrigation, or hand water your most important plants. Once established, many roses will grow well with limited water.
If a recently transplanted rose is showing symptoms like wilt or dropped foliage and buds, it may be suffering from transplant shock. It sometimes takes roses a while to recover from the move and adjust to their new home.
Roses have two types of roots. Thick woody roots that stabilize the rose in the soil, and thin, fiber-like feeder roots that look like little white hairs. These fine roots are responsible for the absorption of water and nutrients. When moving a rose, they often get disturbed or damaged, causing the rose to go into shock.
If your rose has recently been moved (or newly planted in your garden), make sure to water it well. Remember that roses prefer to be moved during the mild weather of spring or fall. If your rose was moved in the heat of summer, it may take a bit longer to recover.
Watch recently moved roses for signs of stress: wilting, stunted growth, and dropping foliage.
Time your transplant when the rose is dormant in early spring or fall. If you purchased a container-grown rose, give it a week or two to adjust to your conditions before planting it in the ground. If moving a rose already in the garden to a new spot, minimize shock by watering it first, then digging out as much of the root ball as possible.
If parts of the rose look completely dead, prune them back to the next outward-facing leaf node so the plant can conserve energy.rnrnMulch to maintain stable soil temperatures, and water whenever the soil is dry a few inches down. For mature roses, an application of organic fertilizer (try a fish emulsion) can help. It may take a couple of weeks, but most roses will bounce back.
No one wants to see highly anticipated rosebuds wither or drop from the bush. This doesn’t mean your rose is a goner. Bud Blast can strike for many reasons, most of which are treatable.
First, identify the cause of the stress. Has your weather been fluctuating wildly? Have you been regularly fertilizing? Did you recently move the rose? Are signs of pests present? Once you know the reason Bud Blast is occurring, you can take action to get your rose back to blooming. Good luck, and enjoy your roses!