Red Double Knock Out® Rose – Tree Form

Rosa 'Radtko' (PP#16,202)

Red Double Knock Out® Rose – Tree Form

Rosa 'Radtko' (PP#16,202)

This product is currently out of stock and unavailable.


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


The Double Red Knock Out® Rose Tree is a stunning plant, with a short, upright trunk and a rounded crown of branches. It is about 6 feet tall, but only 3 feet wide – perfect for narrow beds and smaller spaces, where you want height, but not width. The crown of rich-green, glossy leaves is covered from early spring to the first frost of fall with a continuous display of large, rich-red, double roses. No other rose blooms continuously the way a Knockout Rose does. You don’t even need to remove the blooms as they finish, because they naturally fall, and disappear among the new leaves and blooms. This is also a great plant for boxes and planters, where you can plant flowers beneath it for a great three-seasons display.

  • Beautiful small tree with red roses all over the crown
  • Blooms constantly from spring to fall
  • Great way to have taller roses without taking much room
  • Bred to be resistant to all major rose diseases
  • Great for planters and boxes, or in narrow beds

Plant the Double Red Knock Out® Rose Tree in a sunny spot, with no more than a couple of hours a day of shade. Plant it in any well-drained soil, including even heavy clay and alkaline soils. In very sandy soils, give plenty of attention to regular watering. Use rose fertilizers during the growing season to give the best continuous flowering. Prune lightly in spring, removing any weak branches, and shortening the main one back to between 6 and 12 inches long. Be careful not to remove the upper branches from the stem completely, as the trunk is a different type of rose.

Plant Hardiness Zones 5-9
Mature Width 3-4
Mature Height 5-6
Sun Needs Full Sun, Partial Sun
Zones 5-9

Nothing says ‘roses’ like a double red rose, but growing roses in your garden involves a lot of work, you probably think. Well yes, or at least, it used to, but not anymore. Today we have the Knockout Roses, a breakthrough in rose breeding that has all but eliminated the need for disease control and given us a longer rose blooming season than was ever thought possible. An outstanding variety of the Knockout Rose is the Double Red, which has magnificent large, deep red fully-double flowers from spring to fall. This rose begins to bloom very early, and it flowers continuously until the first frost – a truly remarkable plant. It is one of our best sellers, and its compact size is a real winner for many gardens. Growing just 3 to 4 feet tall it is ideal for smaller gardens, the front of larger beds or the middle of smaller ones, and even for planters or large pots. But sometimes we simply want something taller, so what if we could have the Double Red Knockout Rose growing to 6 feet tall?

We talked to our expert growers, and they had a solution. They took a special rose used only by growers, that has vigorous roots and a strong, thick, upright trunk. Then they attached stems of the Double Red Knockout to the top, and wow, a rose tree reaching 6 feet tall, with fabulous bright red double flowers crowding the rounded crown all season. Just as tough, just as disease resistant, just as long flowering, and of course just as beautiful as the original.

Growing Double Knockout Rose Trees

There are many uses in the garden for the Double Red Knockout Rose Tree. In a smaller space, or a narrow bed, we often need some height without a lot of width, and almost all flowering shrubs are rounded, so a 6-foot shrub is generally 6 feet wide, or even more. The beauty of using this Rose Tree is that it is still only 3 or maybe 4 feet wide across the crown. It takes up so little room, and yet it brings those wonderful blooms right up where you can see them perfectly. Imagine a row of these plants lining a walkway, or that narrow space between a driveway and fence, that so many gardens have. It is also perfect for planters and large boxes, where you can plant smaller shrubs or flowers underneath for two levels of color for months. Indeed, take a look at our Drift Roses – they would grow perfectly beneath these rose trees and make a stunning floral display for months and months. Rose Trees also look great among other flowering and evergreen shrubs, in the middle part of a larger bed, with smaller shrubs in front, and larger ones behind.

Planting and Initial Care

Grow your Double Red Knockout Rose Tree in full sun, or in a spot with no more than a couple of hours a day of shade. Plant it in soil enriched with compost, manure, or other organic materials, and feed it regularly with rose food, for the best continuous display of blooms. It will grow well in almost all soils, including clays, if they are well-drained. Roses of all kinds are top choices for heavy, clay soils, thriving where many other shrubs just fail. It will not grow so well in very light, sandy soils, but both acid and alkaline soils are fine for it. Water regularly when newly planted, and also during drier periods. If your bush is growing in dry soil, and is well-established, it will be fine, but it may stop flowering for a few weeks, which would be a shame. To avoid that keep it well watered, but not flooded. An outstanding feature of all the Knockout Roses is their amazing resistance to the major rose diseases. Black-spot, Mildew or Rust will be things of the past, and spraying is no longer needed with these fabulous roses. You may see the occasional insect pest, but this rose is so vigorous, constantly sending up new shoots, that pests are very rarely any kind of serious problem at all.

History and Origins of the Double Knockout Rose Trees

When the rose breeder Will Radler gave us the first Knockout Rose over 20 years ago, he captured the 2000 All-America Rose Selections prize with it. That coveted trophy isn’t just for a pretty flower. Plants are grown across the country in many regions, to see how they react in different climates, and how people like them. So this prize is virtually a guarantee that wherever you are, this rose will perform just great. He called that first rose, with its open red flowers, ‘Radrazz’, and patented it. 

Plant breeding usually starts with a handful of carefully created seeds, and when they are grown there may be quite a bunch of seedlings, very similar in many ways of course, but also different from each other. Among the brothers and sisters of ‘Radrazz’ that Radler grew, he found another red one that was just as tough, but this one had more petals – about 35 – in every flower, and it was a fully double bloom. That one he called ‘Radtko’, or the Double Red Knockout Rose. It too was patented, and we asked the licensed growers to turn some into rose trees, by grafting stem pieces onto a sturdy, upright trunk. When the plants bloomed, we were thrilled by how gorgeous they looked.

We feel very lucky that we received these beautiful plants, and so do our many rose-loving clients. So if you want one or more for your garden, we suggest you order right away, because these specialty items never last long – don’t delay, get them right away.

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Red Double Knock Out® Rose – Tree Form

Rosa 'Radtko' (PP#16,202)