How to Grow Red Knockout
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Red Knockout
Rosa 'Red Knockout'
shrubRed Knockout is a disease-resistant landscape rose known for its prolific clusters of deep red, semi-double flowers that bloom continuously from spring through fall. This vigorous shrub rose is low-maintenance, hardy, and requires minimal deadheading, making it an excellent choice for borders, hedges, and foundation plantings. It was introduced in 2000 and won the prestigious All-America Rose Selection award.
When should you plant Red Knockout in your zone?
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Example Red Knockout timeline · Pittsburgh, PA (Zone 6b)
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Plant Red Knockout
Around Apr 17Near Pittsburgh's average last spring frost.
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Tend & protect
Late spring–summerWatering, feeding, and pest-watch reminders.
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Harvest Red Knockout
Late summer into fallBefore the first fall frost (≈ Nov 8)
Sample dates for Pittsburgh, PA. Sign up to get exact Red Knockout dates for your own zip code.
Growing Conditions
Soil
Growing Zones
Find your zone →Thrives in zones 4b-10a; most vigorous in zones 5-9
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Establishment
2-4 weeksFresh transplant with initial leaves and shoots; plant is actively establishing root system
Water regularly and deeply to encourage root development. Apply 2-3 inches of mulch around base. Avoid fertilizing heavily for first 2-3 weeks.
Early Growth
4-6 weeksVigorous vegetative growth with abundant foliage; canes lengthen and branch prolifically
Begin fertilizing every 4-6 weeks with rose fertilizer or balanced formula. Prune out any diseased or damaged wood. Monitor for pests.
First Flowering
3-4 weeksInitial flower clusters appear at branch tips; flowers are deep red, semi-double blooms in clusters
Minimal deadheading needed; the plant drops spent flowers naturally. Continue regular watering and feeding schedule.
Continuous Bloom
4-6 months (spring through fall)Persistent flowering throughout growing season with abundant clusters of deep red flowers; strong fragrance
Maintain consistent moisture and fertilize every 4-6 weeks. Light shaping or pruning of long canes encourages bushier growth and more blooms.
Dormancy & Winter
2-4 months (November through February)Foliage yellows and drops; canes go dormant. In cold zones, canes may die back partially or completely
Prune back by one-third in late winter/early spring. In zones 4-5, apply 12 inches of mulch or use rose cones for protection. No watering needed during dormancy.
Companion Planting
Plan your garden →Plant with:
Avoid planting near:
Common Pests
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Hand-pick in early morning, use Japanese beetle traps away from roses, apply neem oil or insecticidal soap
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Increase humidity with regular misting, spray with strong water spray, apply insecticidal soap or horticultural oil
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Spray with water, apply insecticidal soap, neem oil, or introduce beneficial insects like ladybugs
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Remove affected flowers, spray with neem oil or insecticidal soap, improve air circulation
Uses
Landscape screening and borders
OrnamentalRed Knockout's vigorous growth, disease resistance, and continuous blooming make it ideal for creating color-filled hedges, foundation plantings, and border displays. It can reach 3-4 feet tall and wide, providing excellent landscape structure. [source]
Rose hip tea and edible flowers
CulinaryThe deep red hips that form after flowering contain high levels of vitamin C and can be dried for herbal tea. Individual petals can also be used as an edible garnish for salads and desserts. [source]
Pollinator and wildlife support
WildlifeThe semi-double flowers provide pollen and nectar for bees, butterflies, and hummingbirds. Fall hips serve as food for birds during winter months. [source]
Herbal remedies
MedicinalRose petals and hips have been used traditionally to support immune function and reduce inflammation. Rose water and petals are used in various herbal preparations. [source]
Fragrance and aromatics
HouseholdFresh cut flowers release a pleasant fragrance indoors and can be used in dried flower arrangements, potpourri, or to infuse oil for natural fragrance products. [source]
This is not medical advice. LizPlants is not a medical resource. Always consult a qualified healthcare professional before using plants medicinally.
Harvest Tips
Red Knockout is primarily grown for ornamental display. Cut flowers can be harvested in early morning by cutting at 45-degree angles with sharp pruners, cutting at least 12 inches of stem. Cutting for arrangements encourages additional blooms. For hip production, stop deadheading in late summer to allow hips to form for fall color and wildlife food.
Fun Facts
- 🌱 Red Knockout won the All-America Rose Selection award in 2000 and spawned an entire Knockout series including Pink, Yellow, Double Pink, Double Red, and Coral Knock Out varieties.
- 🌱 Unlike many ornamental roses, Red Knockout requires virtually no deadheading because the plant naturally sheds spent flowers and continuously produces new blooms, earning it the 'low-maintenance' designation.
- 🌱 The rose is exceptionally disease-resistant, showing strong resistance to blackspot, powdery mildew, and rust—three of the most common rose diseases—due to its strong genetic disease-fighting genetics.
Gardening Terms
New to gardening? Learn about terms used in this guide:
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