Knockout roses care is low-maintenance. This hardy rose is an ideal shrub even for gardeners with limited experience. This family of roses produces vivid red, yellow, or pink rose blossoms starting in late winter or early spring.
Bred for disease-resistance, this member of the Rosaceae family is also known to generate very few hips. So, when do Knockout roses bloom, and how long do knockout roses bloom?
When Do Knockout Roses Bloom?
With ideal conditions, Knock Out rose bushes start to bloom in the early spring. These roses’ normal bloom cycle is around five to six weeks and can begin as early as late winter.
From April to November, it is possible to see up to seven bloom cycles of blooms from the Knock Out rose. This growth rate is only somewhat dependent on the care and weather conditions they experience during the growing season.
How Long Do Knockout Roses Bloom?
The Knockout rose is disease resistant and with a self-cleaning nature allowing petals to fall off on their own tidily. This trait reduces the number of rose hips that form after the flowers drop.
Rose hips are seed pods that contain hormones that let the plant know that it can stop blooming. Because of the smaller number of these rose hips, Knock Out roses continue to produce new blooms throughout the entire season.
Tolerating both desert heat and a minimum temperature of negative 15° degrees Fahrenheit, this plant is ideal for states in the US’s southern region. Once the initial bloom occurs, Knock Out roses will repeat the blooming cycle through the summer season until the first hard frost.
To Prune or Not to Prune?
Pruning and deadheading the Knockout rose can be helpful but is not necessary in most cases. It can grow up to 5′ feet tall when left to its own devices.
Once the frost threat passes, pruning with hedge loppers to about 12″ will allow for 3′ to 4′ feet worth of growth throughout the season. Pruning at least once at the start of the season is a good rule of thumb. Make sure you wear heavy gardening gloves when pruning.
Since the Knockout rose is self-cleaning, the need for deadheading is minimal to none. While the plant will grow without removing the faded blooms, it can help keep it looking clean and tidy. The removal of old buds can potentially encourage blooms as well.
Having Trouble with Knockout Roses Blooming?
Like other Rosaceae family members, Knockout roses are susceptible to issues with healthy or adequate growth. The first step to solving any problem is to find the source, which can be anything from inadequate care of rose plants to pests.
Fertilizer & Water
The best fertilizer for Knockout Roses targets both the root zone and the upper areas of Knockout roses to assist with growth. Additionally, too much nitrogen can encourage too much foliage and few blooms.
Deep, regular waterings are ideal for keeping this plant healthy. Overhead watering, however, is something to avoid. Hot days with not enough water can cause KnockOut roses to go into shock.
Overwatering is a problem as well, so it is best to find a balance. A long, saturating drink of water every once in a while is better than frequent watering.
Knockout roses need at least 6-8 hours of full sun. Keep this in mind when deciding on a location. For days with intense heat or sunlight, some partial shade can help provide some relief.
Pest and Disease Control
Both animals and insects can feast upon Knock Out roses. Missing buds and foliage can indicate that deer or even squirrels are helping themselves to the plant. Repellents and fencing can help ward them off.
Rose slugs, beetles, or thrips can also find a home in Knockout roses. While hardy and resistant, deal with these pests by picking beetles off one by one or using insecticides.
Knockout roses are resistant but not immune to powdery mildew fungal disease, black spot, and even rust can cause stress. More on Knock Out Rose diseases.
Leaving black spots alone, along with proper watering at the plant’s base, can discourage any more from forming. Some leaves may drop, but black spots do not generally affect the plant’s health overall.
Trimming back powdery mildew or applying a Neem oil spray to your roses or a horticultural oil at the first sign can reduce the spread.
But, humidity, mild temperatures, and overcast skies can be the cause. , and the problem may go away when the weather conditions improve.
To keep Knock Out roses safe during a harsh winter, add 2″ – 3″ inches of mulch around the plant’s base.
Related: Preparing Knockout Roses For Winter
Burlap wraps or heavy snow cover can help protect Knock Outs during snowfall and cold temperatures.