Double Knock Out® Rose

Double Knock Out® Roses are hardy in USDA zones 5 to 10 and bloom best in full to part sun — aim for at least six hours of direct light a day. They are not fussy about soil but want a spot that drains well; heavy, soggy ground is the main thing to avoid.

Planting

1. Choose a site with full to part sun and good air circulation, which helps keep the foliage dry and healthy.
2. Loosen the soil and work in compost if your ground is heavy clay or very sandy, improving drainage and fertility.
3. Dig a hole about twice as wide as the root ball and no deeper than the root ball is tall.
4. Set the plant so the crown (where the stems meet the roots) sits at or just slightly above the surrounding soil level, then backfill and firm gently.
5. Water in thoroughly to settle the soil, then spread 2 to 3 inches of mulch around the base, keeping it pulled back a few inches from the stems.

Care & maintenance

• Water. Keep the root zone evenly moist the first growing season while the plant establishes. Once settled it is quite drought tolerant; water deeply during prolonged dry spells, ideally at the base rather than overhead.
• Feed. Apply a balanced rose or all-purpose fertilizer in early spring as growth begins, and again in early summer. Stop feeding by late summer so new growth has time to harden before frost.
• Light. The more sun it gets, the heavier the bloom — full sun produces the most flowers, though it tolerates a few hours of afternoon shade.
• Prune. This shrub blooms on new wood, so prune in late winter or early spring before growth resumes. Cut the plant back by about one-third to one-half to a tidy mound; it responds with vigorous new shoots and a strong first flush. Light shaping between flushes is optional.
• Mulch & winter care. Maintain a 2-to-3-inch mulch layer to conserve moisture and moderate soil temperature. In colder zones, a deeper mulch over the crown adds winter protection.
• Pests & disease. Bred for strong resistance to blackspot and powdery mildew, it rarely needs spraying. Watch for aphids on tender new growth and Japanese beetles in summer; a strong jet of water or hand-picking usually keeps them in check.

When does it bloom and how long?

It produces flushes of cherry-red double blooms from spring all the way through fall — one of the longest bloom windows of any landscape rose. Because it is self-cleaning, it keeps cycling into new flowers without deadheading.

Why isn't my Double Knock Out blooming?

The most common reasons are too little sun, pruning at the wrong time, or over-feeding. This rose needs at least six hours of direct sun for heavy bloom. Since it flowers on new wood, prune in late winter or early spring — pruning hard in summer removes developing flowers. Too much nitrogen also pushes leafy growth at the expense of blooms.

When and how should I prune it?

Prune in late winter or early spring before new growth starts. Cut the whole shrub back by about a third to a half to a rounded shape; it blooms on new wood, so this hard cut fuels a strong spring flush. You can lightly trim between flushes to keep it neat, but it is not required.

Does it need full sun or will it take some shade?

It performs best in full sun and will bloom most heavily there. It tolerates part sun and a few hours of afternoon shade, but the deeper the shade, the fewer flowers you will see and the more likely foliage problems become.

Is it really low-maintenance and disease resistant?

Yes. It was bred specifically for strong resistance to blackspot and powdery mildew, the two issues that plague most roses, so it generally thrives without a spray program. Apart from one annual prune and occasional feeding, it asks very little.

Can I grow it in a container or as a hedge?

Both work well. Its compact 3-to-4-foot habit makes it ideal for a large patio container with good drainage, and planted in a row it forms a colorful, informal low hedge that blooms for months. It is also right at home in foundation plantings and mixed borders.