Knockout roses yellowing leaves

I receive a huge amount of questions about growing The Knock Out® Family of Roses and it’s easy to understand why they are so popular.

The original Knock Out® Rose was introduced in 2000 by The Conard-Pyle Co./Star® Roses. Created by Wisconsin rose breeder William Radler to reduce the rose gardener’s to do list with a plant that was cold hardy, disease resistant and incredibly floriferous. Knock Out® is cold tolerant to zone 5, heat tolerant throughout the U.S., reliably resistant to disease and produces a bevy of blooms every 5 to 6 weeks from spring until the first hard frost. I’d call that success! No wonder it won the AARS Award that year.

P. Allen Smith now has a dedicated place for all your Knock Out and Drift Roses. View it here

There are seven beautiful members of The Knock Out® Family of Roses in a wide range of colors ranging from cherry red to creamy yellow.

The Knock Out® Rose

The Double Knock Out® Rose

The Pink Knock Out® Rose

The Double Pink Knock Out® Rose

The Blushing Knock Out® Rose

The Sunny Knock Out® Rose

The Rainbow Knock Out® Rose

The natural inclination of The Knock Out® Family of Roses is to grow to about 3′ wide x 4′ tall, but they are easily maintained at a smaller size through pruning. They are ideal for growing in mixed borders, in containers or as a hedge.

Just like other roses, The Knock Out® Family of Roses perform best when planted in full sun. The soil should be well drained and fertile.

Plant the roses 4 feet apart to allow for room to grow and good air circulation.

To keep the flowers coming feed your roses with a fertilizer blended especially for roses. This should be done after each bloom cycle. There is no need to remove faded flowers because these roses are self cleaning – another task you can remove from your to do list!

Prune in late winter or early spring, while the plant is still dormant. Remove any dead or damaged wood, do a little shaping if necessary, and take out some of the interior stems to improve air circulation. Every 2 or 3 years remove about one third of the old branches to stimulate new, fresh growth. If you are trying to keep the roses at a certain height, you can cut them back hard with hedge shears. No need to worry about usual rose pruning rule of cutting back to an outward facing leaf bud – just lop them down to the desired size. I’ve even seen Knock Out® Roses spring back beautifully after being cut down to 6-inches.

Blooming and Fertilizing

My Knock Out® Roses are starting to get black spot.

In some very humid, black spot prone areas, you may see some black spot. Don’t worry—while the plant may drop some leaves, it won’t be detrimental to the overall health of the plant. Make sure when you water your roses, that you water at the base of the plant. Watering overhead (with a sprinkler or hose), leaves water on the foliage which is an invitation for fungal disease. Your Knock Out® Roses will be much happier if you water at the base of the plant. Also, they prefer a long drink of water every once in a while rather than frequent small watering.

What steps can be taken to treat powdery mildew?

Powdery mildew can be a common problem of roses, particularly when conditions are favorable in spring and fall. Powdery mildew is a fungal disease that appears as a soft white coating on stems, leaves, and buds of rose bushes. It commonly occurs when there are many overcast days with high humidity and mild temperatures. Generally speaking, powdery mildew becomes less of a problem after the arrival of summer which typically brings with it long, hot, sunny days. The mildew problem will go away with improved weather conditions. There are a few options for correcting the problem.

  1. An application of horticultural oil should smother the spores and reduce spread of the problem. It is best to try this as soon as possible upon visible symptoms. An early sign of powdery mildew is a slight curling upwards of the foliage.

  2. You could try trimming back the worst affected areas and wait for new, clean growth to flush out.

Voles are eating the roots of My Knock Out® Roses. What can I do?

Traps and poisons are the two most successful methods of controlling voles. If you want to try the organic route, there is a product called Shake-Away Rodent Repellent which uses the scent of fox urine to discourage voles from burrowing into the soil beneath your roses. The product is in a powder form that can be sprinkled around the roses you wish to protect.

Japanese Beetles are attacking my Knock Out® Roses.

Pick each Beetle off and drop them into a bucket filled with warm soapy water. Putting a bird feeder nearby may also help. Japanese Beetles won’t be detrimental to the overall health of the plant so if you can stand them, it’s fine to leave them alone too. You may want to try a product like Milky Spores to control them—we recommend just pulling them off one by one though (not fun but effective).

There are holes in the leaves of my Knock Out® Rose and I don’t see any beetles or other bugs. Any tips?

The leaf damage you are seeing could be from what’s called rose slug (also called sawfly). Look on the underside of the leaves. Do you see any tiny green inchworm looking critters? Rose slugs will chew the leaves of plants—leaving trails where they’ve munched through, but they won’t be detrimental to the overall health of your Knock Out® Roses.

Do we need to protect our Knock Out® Roses from being eaten by insects?

Knock Out® Roses are not pest-resistant, but they are extremely tough so even if bugs get after them, they should be fine. You can use a spray product formulated for roses if the bugs are particularly bad in your area. The best way to remove Japanese Beetles is by hand though—pick them off one by one and put them in a container of warm soapy water. Placing a bird feeder nearby can also be effective!

The deer have eaten most of the blooms on my Knock Out® Roses. Will they bloom again or are they a total loss?

Knock Out® Roses are not deer resistant and unfortunately, as you probably know, when deer are hungry, they’ll munch on anything. Don’t worry though, Knock Out® Roses are really tough. They bloom repeatedly throughout the season, so hopefully when it’s time for them to bloom again, you will see more flowers. You may want to try a product like Liquid Fence to keep the deer away.

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Yellow Blooms + Carefree Knock Out® Growth in Tree Form

Why Sunny Knock Out® Rose Trees?

Setting the standard for carefree color and adaptability, the Knock Out® Rose Tree has raised the bar for disease resistance and carefree upkeep. It’s got all the hardy, reliable growth of the Knock Out® shrub in an even more versatile growth habit…and rich yellow blooms for up to nine months.

The Sunny Knock Out® Rose Tree can be container planted to place beside entryways, on porches and even indoors if temperatures drop. No matter where you place it, though, it’s a unique showcase plant that delivers reliability and masses of full yellow blooms without any effort on your part.

Why is Better

Typical roses grow rather slowly and require lots of pruning, deadheading, and cleaning. But when you order your Sunny Knock Out® from Fast Growing Trees, you’ll soon be rewarded with months of colorful blooms, without all the fuss.

You’ll enjoy instant impact for your yard and garden rather than waiting years to see results. Because your tree has been grafted and then nurtured for months before shipping, it leaves our nursery with a well-developed, healthy root system.

The Sunny Knock Out® is grafted with proven rootstock to combine the benefits of the Knock Out® shrub with a versatile, easy-growing tree form.

This is the hottest rose introduction in years. And these trees will sell out quickly, so order yours now!

Planting & Care

1. Planting: Select a well-drained planting site in full to partial sun (3 to 6 hours of direct morning sunlight with afternoon shade).

Dig a hole twice as wide and twice as deep as the root ball. Backfill the soil until you have a hole the same size or slightly larger than the container the rose is in.

Plant the rose at the same depth as it is in the container. Mulch around the base of the tree to conserve moisture.

To container plant, select a pot that’s twice the size of your tree’s shipped container and ensure it has drainage holes. Then, use organic soil mix and place your tree in its pot. Put your planted tree in a sunny area on your patio or porch.

2. Watering: Water around the roots rather than overhead, and water about once or twice weekly. If you’re not sure when to water, simply check the surrounding soil about 3 inches down. If the soil is dry, water until the ground is moist, or water container trees until you see water escaping the drainage holes.

3. Fertilizing: Feed with a rose fertilizer once a month.

4. Pruning: You won’t have to prune for the first few seasons, but when you do prune, sterilize your pruning shears with rubbing alcohol and always prune at an angle. Start by pruning back a little in the spring after the last hard freeze to your desired shape. You can remove dead or old canes at any time. 79.95 Fast Growing Trees bestsellers check out these plants that look great right now disease resistant disease resistant roses easter plants fall blooming shrubs fall color shrubs and hedges flowering trees fragrant plants fragrant roses gift trees indoor patio plants popular knockout rose trees knockout roses mothers day gift ideas ornamental trees patio plants and trees plants for bad soil rose bushes rose trees roses shrubs and hedges small trees for small spaces spring blooming plants summer flowering shrubs top rated plants Tree Spikes valentines day gifts // // 13940803272756 2-3 ft. 59.95 79.95 // InStock 2-3 ft. 13940803305524 3-4 ft. 89.95 89.95 // InStock 3-4 ft.

Sunny Knock Out® Rose Tree

Show off your happy personality with a wonderful tree-form Rose carefully crafted by the expert growers at Nature Hills Nursery. You’ll adore the unique flair of a Sunny Knock Out® Rose Tree (Rosa ‘Radsunny’).

The deciduous Sunny Knockout shrub produces an abundance of fragrant, single, vivid yellow blossoms that age into a lush, warm vanilla cream. The sunny blooms stand out against the dark, semi-glossy foliage.

Sunny Knock Out Rose Tree blooms prolifically from spring until the first frost. How nice to see those happy little flowers performing for you all through the entire growing season!

Love the smell of citrus? Sunny is one of the most fragrant of the Knock Out® family of Roses. The blooms are infused with a wonderful, fresh scent of lemons and limes.

This bushy Shrub Rose sits atop a sturdy standard trunk. You’ll truly enjoy the fragrance and sight of the blooms, as they are raised up for easy inspection.

These plants are butterfly and hummingbird magnets. You’ll love watching these “flying flowers” flutter and flit in your garden!

Faded blooms will self-clean, so there is no dead-heading required. Lush, shiny green foliage makes a wonderful foil for the brilliant flowers.

Developed to be carefree and extremely hardy, Sunny Knock Out Rose Tree is both disease and pest-resistant. It would love a sunny location in your yard, but would be equally at home in a container on your patio.

We honestly can’t think of a better gift to give someone you love than this cheery little tree. What a fun housewarming present, or a nice way to celebrate a friendship. It’s perfect for one of those “Big Birthdays”, and a wonderful plant for celebrating a healing or sharing sympathy after a loss. It’s easy enough for anyone to care for.

You’ll love this petite accent tree and can tuck one or two in sunny spots all around the yard. They’ll make a great focal point wherever you choose to use them. Order yours today!

How to Use Sunny Knock Out® Rose Tree in the Landscape

The sweet little tree has such pretty yellow blooms and keeps roses growing all through the season. People notice it right away, so use it where you want to draw attention.

If you have the room on your porch or portico, place one on either side of your front door in large, exterior pots for a sophisticated, yet cheery greeting. They’ll appreciate the yummy citrus scent as they approach your home.

Use a single tree in your foundation planting as a small accent near the front walk as a welcoming beacon for your front entrance. Plant in the ground, or use a fun container to coordinate with the exterior finishes of your home.

Underplant the tree with spring bulbs, perennials and groundcover for a textured look that works beautifully throughout the season. Add short, dwarf evergreens to extend the interest over winter.

They’ll make the perfect plant to decorate your patio outdoor entertainment areas. They look fetching in pairs flanking an entrance, or try an odd number placed in a curve behind seating areas.

March a series of them down the length of a garden path to add structure and charm. Or, try this same look as a lovely backdrop for perennial gardens.

For a marvelous look, try using 3, 5 or 7 of these trees as regular punctuation through a long hedge of Sunny Knock Out Rose bushes. Adding the trees brings vertical height to your hedge to easily increase the dramatic impact.

Increase the formality with a disciplined planting plan. For instance, you can plant 3 bushes, then add a tree, then 3 bushes, then a tree and so on. Start and end with bushes for a nice finishing touch on either end. It will look like a million bucks, but the low maintenance level of care stays the same.

#ProPlantTips for Care

Choose a well-drained site for planting in your garden. Rose root systems won’t tolerate wet soil. If you see puddles that last a long time where you hope to plant, you can “mound up”. Add additional soil to a height of 18” and plant directly in the mound.

Elevate containers up off the ground. Use 3 or more bricks in a wide triangle to give a steady base. You want to position the drain hole over the opening in that triangle. Rose trees grown in an outdoor container should not have a saucer underneath, please. Keep the soil drained.

Sun loving Roses perform at their best in full sunlight. Knockout roses in particular are able to handle long, hot days spent baking in the full blaze of the sun. 6 – 8 hours of direct sun are recommended.

New plants will require a moderate amount of regular water to get their roots established in your native soil.. Test before you water by using the “Finger Test” by poking your finger into the soil up to the second knuckle. If it’s getting dry, time to apply water. If it’s still moist, you can skip watering that day. (Pro Tip: use the Finger Test on houseplants, too!)

Knock Out Roses will display drought tolerance once their roots are well established. However, we recommend you baby your Tree Form plant a bit, especially if you are growing it in a container. Set up a drip irrigation system on a schedule to keep things really easy for yourself.

While not required, you can give a balanced Rose bloom fertilizer twice a year, following the directions on the label. Usually, it’s recommended to wait for the first application until after the first flush of blooms are passed. Give the second application no later than mid-summer. Each formula will have different application rates, so be sure to check the instructions.

Knock Out roses are well known for their rugged nature, and disease resistance to black spot, rust and powdery mildew. Give your tree plenty of sunlight for the best results. Diluted organic Neem Oil can be sprayed on the foliage in the evening, if you ever feel like it’s needed. Chances are great you’ll never, ever need to worry about it.

You’ll want to study your tree in early spring once the new growth is leafing out. Remove any crossing, damaged, or “wild” canes that have a mind of their own all the way back just above a new bud.

Make selective pruning cuts to open up the interior of the canopy for more sunlight and air circulation. You can also hard prune the entire canopy back with tip pruning to control size, if desired.

If you’re looking for a happy-go-lucky, easy care Rose with a fresh, modern twist, the Sunny Knock Out Rose Tree is for you. You’ll feel like you captured the sunshine with this pretty selection. Don’t miss out on your chance to own one of your own, order today!

Soil: Prefers medium moisture, slightly acidic, well-drained garden loam. Roses benefit from the addition of compost, aged manure, or leafmold to the planting soil.
Light: At least 5-6 hours of direct sun per day is preferred, though this variety will grow very well in part shade locations with excellent disease resistance.
Water: One inch of water per week throughout their first growing season. A generous layer of organic mulch (compost or composted manure) helps keep the soil evenly moist. If weather is dry in the fall, be sure to water Roses well. Never allow the foliage to remain wet into the evening; water early in the day.
Spacing: 3 – 4 ft.
Fertilizing: To keep the flowers coming feed your roses with a fertilizer blended especially for roses. This should be done after each bloom cycle.
Winterizing: If you live near a rose’s cold limit, and you garden on an exposed site or in an area where rapid temperature fluctuations are common, you should mound two shovelfuls of composted manure, garden soil, compost, or shredded leaves over the base of the plant in late fall after the ground freezes. Covering these mounds and the lower parts of the bushes with evergreen boughs will add protection. Pull the mounding material away from the stem as new growth emerges in spring. Prune branches injured over winter when new buds emerge in spring.
Maintenance & pruning: Cleaning up old foliage is important for disease control. Prune to remove deadwood, to control or direct growth, and to promote flowering. Wait until growth breaks from the canes in early spring before pruning. Every 2 or 3 years remove about one third of the old branches to stimulate new, fresh growth. If you are trying to keep the roses at a certain height, you can cut them back hard with a hedge shears. No need to worry about usual rose pruning rule of cutting back to an outward facing leaf bud; just lop them down to the desired size. There is no need to remove faded flowers, because these roses are self cleaning.

Question for Dan Gill: Last year I noticed the yellowing and brown spotting of some of the leaves on my Knock Out roses. The same thing is happening this year. Can you diagnose and suggest what to use? For some reason I thought Knock Out roses were virtually disease free. Also, a few of my daylilies are showing rust spots on the foliage. Should I dig them and discard? —Debora

Answer: The yellow leaves are likely the result of black spot disease. Knock Out roses, in general, are quite resistant (not immune) to black spot disease. During wet weather conditions, however, even resistant plants can be attacked to some degree. That’s what’s happening now to your Knock Out roses. Still, there is no need to spray. The rose will get over this disease on its own without your intervention and look better eventually. Rake the fallen leaves regularly and dispose of them.

Blame the wet spring for the bad outbreak of daylily rust this year as well. Daylily rust was first reported in the Southeastern U.S. in 2000 and has spread rapidly to many states including Louisiana. The disease causes the foliage to yellow and brown. Turning an infected leaf over you will see orange raised spots on the back of the leaf. The rusty orange spores will rub off on your finger.

Knock Out roses add no-fuss beauty to the landscape

Susceptibility of daylily cultivars to this disease varies, some are very susceptible and others seem fairly resistant. Gardeners have the choice of eliminating the very susceptible cultivars that show the worst symptoms and retaining those that don’t seem to be bothered as much by the disease.

Should a gardener decide to treat the disease, the infected plant should be cut within an inch of the ground, and it and all the plants around it should be sprayed regularly with a fungicide. Recommended fungicides include mancozeb (Dithane, Fore), chlorothalonil (Daconil), azoxystrobin (Heritage), propiconizol (Banner Maxx) and triadimefon. Application may need to be repeated as often as every seven to fourteen days – follow product label instructions.

Since most of us will not want to cut our daylilies back just as they are blooming or spray constantly, it is likely that the solution to this problem will be to eliminate highly susceptible varieties and utilize existing and develop new cultivars that are resistant to the disease. More information can be found online here.

How to pick the right rose for your garden

Dan Gill is a horticulturist with the LSU AgCenter. Email questions to [email protected] or add them to the comment section below. Follow his stories at

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