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White Knock Out® Rose

Rosa 'Radwhite' (PP #20,273)

White Knock Out® Rose

Rosa 'Radwhite' (PP #20,273)

This product is currently out of stock and unavailable.

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How are the heights measured?

All tree, and nothin' but the tree! We measure from the top of the soil to the top of the tree; the height of the container or the root system is never included in our measurements.

What is a gallon container?

Nursery containers come in a variety of different sizes, and old-school nursery slang has stuck. While the industry-standard terminology is to call the sizes "Gallon Containers", that doesn't exactly translate to the traditional liquid "gallon" size we think of. You'll find we carry young 1-gallons, up to more mature 7-gallons ranging anywhere from 6 inches to 6ft.

How does the delivery process work?

All of our orders ship via FedEx Ground! Once your order is placed online, our magic elves get right to work picking, staging, boxing and shipping your trees. Orders typically ship out within 2 business days. You will receive email notifications along the way on the progress of your order, as well as tracking information to track your plants all the way to their new home!

Why are some states excluded from shipping?

The short & sweet answer is: "United States Department of Agriculture Restrictions." Every state has their own unique USDA restrictions on which plants they allow to come into their state. While we wish we could serve everyone, it's for the safety of native species and helps prevent the spread of invasive disease & pests. We've gotta protect good ole' Mother Nature, after all.

About Me

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The White Knock Out® Rose is amazing in so many ways. The purity and beauty of the pure-white blooms is outstanding, and this rose, considered to be perhaps the longest blooming rose of all, is in flower from late spring all the way into fall, without a break. Clusters of white flowers contrast against the exceptional dark-green of the smooth, matt foliage, making a striking mound of beauty that really will knock you out. Growing no more than 4 feet tall, it is perfect to brighten all your shrub beds, or grow along a path or fence. Spectacular in pots and planter boxes too, there is nowhere in your garden it won’t transform.

  • Large white blooms in abundant clusters
  • Flowers from late spring continuously into fall
  • Beautiful contrast of very dark-green foliage
  • Considered the rose with the longest bloom season of all
  • Disease resistant and cold hardy

Full sun will be best for your White Knock Out® Rose, but it will be just fine in an hour or two of shade each day as well. Plant it in well-prepared soil that is rich but well-drained. It grows well in clay soils, and in ordinary garden conditions, with much better drought resistance than most other roses. It continues to bloom through hot, dry weather, but always benefits from regular watering. Prune and fertilize in spring for the best results. Resistant to both blackspot and rust.

Plant Hardiness Zones 4-10
Mature Width 4
Mature Height 4
Zones 4-10

The gorgeous purity of white makes it one of the best and most effective colors in any garden. It doesn’t matter what colors you already have, it blends perfectly. A scattering of white through a shrub bed will unify all the other things going on, turning a random collection into an Insta-ready shot you will be proud of. It brightens dull areas, looks great against dark brick or wood, and doesn’t fade into the background as darker colors often will. So imagine if you could add white from late spring into fall, all through your garden, what a transformation it would be. Well now you can, without trouble, by adding the magnificent White Knock Out® Rose. Don’t worry, this isn’t one of those old-style roses that needs tons of work and then produces just a few flowers. No, this is a fabulous shrub that is easy to grow, endlessly in bloom, and that can be grown anywhere in the country. Featuring very dark green foliage on a dense bush, it is studded with a profusion of open, white, cup-shaped blooms 3 inches across with a soft floral fragrance. These are produced in clusters from late spring all the way into fall, in a continuous display of beauty. Wow! Bring it on!

Growing the White Knock Out® Rose

Size and Appearance

The White Knock Out® Rose is a deciduous shrub that grows to between 3 and 4 feet tall and wide, making a dense, bushy plant with foliage to the ground. The leaves are divided into between 3 and 7 smaller leaflets, each about 1½ inches long, oval, with serrated edges. New leaves are such a rich dark green they are almost black, and they mature to a wonderful deep green, with a smooth, matte surface. With excellent disease-resistance you can sleep easy, knowing that the leaves aren’t going to yellow and fall off – your bush will be leafy and bushy all through the season.

The first blooms will begin to appear by late spring, not long after your bush puts on it’s leafy coat for the year. Flowers are in clusters of about 5 at the ends of every shoot, and each soft-pink bud opens into a 3-inch bloom of 10 open petals, forming a bowl surrounding a center of bright-yellow stamens. At first the petals are pale creamy-yellow, and give off a soft floral perfume. As they open fully they quickly turn pure, icy white. Your bush is smothered in blooms more-or-less continuously from then, flowering right into fall. This rose has one of the longest blooming periods of any rose-bush, so endless flowers are going to be yours, every season.

Using the White Knock Out® Rose in Your Garden

Fill empty spots in your shrub beds with the White Knock Out® Rose. Plant a row along a path, drive or fence. Grow it on banks, and at the foot of walls. Plant a group in a special bed out on the lawn. In warmer zones, grow it in planter boxes and pots on a terrace, up the sides of steps or on your porch. Use it among perennial flowers too, in front of tall grasses or surrounded by annuals. Wherever you plant it you will love it, you can be sure of that.

Hardiness

The White Knock Out® Rose has amazing hardiness, growing without winter protection in zone 4, and also growing right into the hottest places, in zone 10 and 11. It can literally be grown successfully anywhere in the country. From zone 6 you can grow this rose in planter boxes left outdoors for the winter.

Sun Exposure and Soil Conditions

Like all roses, the White Knock Out® Rose grows best in full sun. Avoid shady places, where it won’t bloom much, but an hour or two of shade each day is not going to harm it. It grows best in rich, moist but well-drained soils, and is happy in clay soils too. Plenty of organic material, dug in before planting, and used as mulch, will always give the best results when growing roses. This variety has been tested for drought resistance, and performs well, continuing to bloom during summer heat and dryness much better than most roses will. Regular watering, though, will give the best results.

Maintenance and Pruning

So vigorous it shakes of any minor pests, and very resistant to blackspot and rust, you won’t need to use harsh chemicals to grow the White Knock Out® Rose successfully. Use rose-food in spring, and use a liquid rose-food through the season when growing in planters or pots. Remove spent flower clusters back to the first full-size leaves, once they are over. This will stimulate new growth, but this rose is so vigorous new shoots will come even if you don’t get round to dead-heading. In later winter or early spring remove weak branches and shorten back the stems, leaving a framework of sturdy stems about 12 to 18 inches long. This will stimulate vigorous new shoots and give you the best bushes for many years.

History and Origin of the White Knock Out® Rose

It is over 20 years now since Will Radler introduced his first ground-breaking Knock Out® Rose. It became a big hit, and transformed rose growing. Since then he has introduced more, all just as good. He began his creation of the White Knock Out® Rose by collecting some seeds from an older shrub rose called Carefree Beauty® (‘Bucbi’). Among the seedlings was one he named ‘Radmom’. He then used pollen from another of his roses, called Alaska or Pink Beauty (‘Radsweet’) and used it on ‘Radmom’. Among the seedlings of that cross was one that stood out for its beautiful blooms and non-stop flowering. He named it ‘Radwhite’ and in 2009 he was granted a patent on it. It is made available as White in the Knock Out® range of roses.

Buying the White Knock Out® Rose at the Tree Center

We love making different Knock Out® Roses available to our customers – we know how well they perform, and how loved they become. If you like white you will simply adore the White Knock Out® Rose, and be so glad you planted it. But order now – we can never keep these roses in stock, they are so popular they just fly off the farm.

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White Knock Out® Rose

Rosa 'Radwhite' (PP #20,273)