'Knockout' advice

sequoia54(z6a MA)August 6, 2010

The photos and comments about the Knockout rose prompts me to ask: why is mine looking so lousy? (I would post a photo but right now my driveway's being repaved--no place to stand and take a picture!) It's still puny after 2 years in that location--about a foot tall--the leaves that didn't get eaten by rose slugs are yellowing and/or spotty, and it only put out one or two blooms. It's in a relatively sunny spot (though shaded late in the afternoon by trees a hundred feet away), sandy soil, but near the spot where a peony thrived for many years. (The soil did get disrupted a few years ago when a sewer line was put in, so the richer layers may have been dispersed.) I'm sure I need to improve that soil now, and attempt to deal (organically) with the insects and/or disease; perhaps it needs to be moved to an even sunnier place. Are any of these factors more important than others, in people's experience? I'd like to hear what has worked for others--thanks!


Thank you for reporting this comment. Undo
sue36(Z5 Maine)

I don't have advice because my 3 look awful. I am considering getting rid of them. They look ok early in the season, then they get eaten by something that causes lots of little holes, then they get eaten by the Japanese Beetles (I mean, totally covered, really gross), then they turn yellow and dry up. My soil is excellent, everything around them does great. I think they are overhyped.

    Bookmark   August 6, 2010 at 1:39PM
Thank you for reporting this comment. Undo
vickima(z5 MA)

I'll come to their defense. A knockout was one of the first shrubs I bought as a new gardener. The pic below was taken on June 8. This one is about 4 years old, but did well from the first year it was planted. I cut it way, way back this spring because it was getting so big. I'm still not happy with the shape, but it's my test rose to learn how to prune.

We did have big problems with rose slugs and that was depressing. But I learned that one well-timed spraying with spinosad in the spring just as they are coming out will prevent damage. This year I didn't see any damage after I sprayed. Japanese beetles do swarm on them. I put milky spore down a few years ago, so we have them, but maybe not in as high quantities as elsewhere. This year the beetles came after the first flush of flowers, so they weren't so obnoxious.

This shrub will keep flowering, and heavily, until frost. I bought another one a few years ago that hasn't done as well. It almost died it's first year and it hasn't been as fast to take off as the other. I think full sun helps a lot. I keep them well watered and fertilize 3 or 4 times in spring and summer.

So, if you can't tell, I'm kind of fond of them. :)

    Bookmark   August 7, 2010 at 1:59PM
Thank you for reporting this comment. Undo
tree_oracle(z6b MA)

For all of my roses, I dig a hole 2ft wide, 2 ft long, and 2 ft deep. Then I take about a third of the soil that I dug out and mix it with equal parts compost and peat moss. The resulting mixture is very rich. After planting the rose, it needs to be watered regularly that first year. I also surround it with compost as a mulch. Your roses are either not getting enough water or food or both. Knockout is not as fussy as most roses but it is a rose nevertheless and all roses are heavy feeders and drinkers. Once Knockout is established, though, external watering is not needed very often as long as the soil is prepared properly and the rose is mulched. I haven't watered mine a single time this year and they haven't skipped a beat. I pruned them hard in the spring to no more than 2 ft tall and they are all 5-6 feet tall right now. Mine have a western exposure so they get sun basically from late morning on and needless to say it is very hot on that side of the house.

    Bookmark   August 7, 2010 at 4:17PM
Thank you for reporting this comment. Undo

Like Vikima, I, too, must come to the defense of 'Knockout'. . .over the past
few years I have planted dozens of them, and they have all done well - without
spraying, without undue watering, and with only one heavy pruning in earliest
Spring, way back to 2' minimum. Tree Oracle's advice about proper planting,
mulching and first-year watering is dead on; those K.O's that got less than
optimum treatment at the outset have ALWAYS shown their displeasure to me
by not growing robustly. . .most of the others have exploded into 4'-5' shrubs
(and as wide). When I go back and actively add compost, mulch and provide
sufficient water, these roses always respond - indeed, there is one in my own
garden which has been lifted and moved three times over five years, and it's
still thriving. The half-dozen K.O.'s we planted in our town's "signpost" gardens as you enter town, are so substantial and long-blooming, that we
no longer have to add very many annuals to the beds.

Do we get beetles? Sure, but one of our only maintenance chores is going
around town popping the beetles into cans of soapy water. . . and actively
dead-heading. My suspicion about the bad rap that Knockouts sometimes
get, is that they are so heavily touted as "strong" and "carefree" that many folks misinterpret that to mean they can be "abused" and/or "ignored" .
Really successful plants tend to result from really good care. . .oh, all right,
I can think of a few exceptions! . . .but you get my drift. . .


    Bookmark   August 7, 2010 at 9:32PM
Thank you for reporting this comment. Undo
kathyannd(Zone 9b)

I'm also a member of the Knock Out Fan Club. Carl said it best, I think. Like any other plant, they do need a nominal amount of care. Compared to some roses, they may seem to thrive on neglect, and while they need way less care than most roses, they do need SOME care and feeding.

We have them growing in sun and shade at home and in bright sun in the middle of the city at another location and they are all thriving. We give them a boost of compost and manure in the spring and fall, feed once and prune once, and we also use milky spore to help with the beetles. We have been rewarded with gorgeous blooms all season and well into November. Once, when the Japanese beetles get terribly nasty on all of our many roses, we added Neem to our regular totally organic/natural spray and that helped a lot.

We rarely deadhead. The only advantage is that pruning lightly when dead heading speeds growth and the rebloom cycle happens more quickly as well but it's not necessary. Even the plants we don't deadhead rebloom liberally.

We recently planted 15 of the double Knock Outs at the local Masonic Lodge which is in the middle of the city. They have not disappointed us - they are blooming, thriving, and have tripled in size since we planted them in May.

My advice is to amend the soil, feed it, prune it back, and lightly fertilize it again in the fall. We handle garden pests naturally. For slugs, we dust with food grade DE. Otherwise, we spray our entire garden with a mix of homemade peppermint tea and garlic oil, clear soap, baking soda, and canola oil in water.

I have them growing in bright sun and nearly full shade and while the shaded plants are a little less robust, I've never found any other rose that can handle nearly full shade, under pines, and still bloom as gloriously as these do. In my experience, with a minimal amount of time and attention, they easily outperform rugosas and even the hardiest, most disease and pest resistant tea roses every time.

    Bookmark   August 9, 2010 at 11:45AM
Thank you for reporting this comment. Undo
claireplymouth z6b coastal MA

Now is the time when I really appreciate the Knockout roses.

This is one of my classic Knockouts on October 19, 2010. It's about 5 ft tall.

My all time favorite is Blushing Knockout - blooming today (October 20, 2010). There are two roses here, each at least 6 ft tall.

I don't prune heavily, I just deadhead during the warm season. I stop deadheading at the beginning of September so as not to encourage new foliage growth. They're fertilized once a month with RoseTone - last feeding mid-September. They all have new unopened buds on them.


    Bookmark   October 20, 2010 at 8:49PM
Thank you for reporting this comment. Undo
claireplymouth z6b coastal MA

I should have included this photo taken yesterday (Oct. 19) to give an overall picture of the Blushing Knockouts.


    Bookmark   October 20, 2010 at 9:17PM
Thank you for reporting this comment. Undo

Well, dang, folks, I can see I need to go get some of these. I can certainly find the space for something that looks that nice at this time of year.

    Bookmark   October 20, 2010 at 11:12PM
Thank you for reporting this comment. Undo

Another Knockout fan from Costal, MA. The six planted here have been in continuous bloom since May 8 and still look lovely today. They received the proper love and care at planting and each plant has its own soaker connected to our irrigation system. In the spring I will be replacing the six Dorothy Perkins planted that same day in a different location with Knockouts!

    Bookmark   October 20, 2010 at 11:21PM
Thank you for reporting this comment. Undo

I am not such a Knock Out fan because I grow lots of roses and find the Knockout to be less interesting than my other roses but I think they are great en masse for landscaping. I give my Knockout the same treatment that I give all my roses: sun; Rose Tone once a month from spring to September; pick off and drown the JB's; water as needed.

    Bookmark   October 21, 2010 at 8:00AM
Thank you for reporting this comment. Undo
claireplymouth z6b coastal MA

I want to note two unusual things about my roses:

1. All of my reblooming roses, Knockouts and others, pretty much stop blooming when it gets really hot in the summer. When the weather gets cooler they pick up and start blooming again. I don't think it's a fertilizer issue since I feed them monthly. Maybe it's because they're mature and don't need to put out much new growth?

2. I don't have a Japanese beetle problem, probably due to the large number of birds I pander to, aided by skunks.


    Bookmark   October 21, 2010 at 8:49PM
Thank you for reporting this comment. Undo

I too sing their praises. Right now, end October, they are still pumping out blooms. And so is Betty Prior, another fabulous -- and hardy -- specimen. This is my advice. Like tree oracle said above, prepare well, and this will pay off. There is a rose saying to heed well: "Don't put a 25 dollar rose in a 25 cent hole." If there is anything I HATE, it's having an expensive plant die or not thrive. So I really prepare the hole carefully. I also think WHERE you get your roses matters a lot. I always buy bareroot -- ordered from reputable places, since I figure out in advance what I want, and use the internet to get them rather than driving around to nurseries in a hit-or-miss fashion, being subject to what they have. I think bareroot is the way to go -- you can see the healthy roots, and planted in early spring -- April here in NW CT -- the roots have time to develop first under the earth, and then later, the branches and flowers come in due course. I have given my knockout blush roses my tried-and-true treatment, and they have grown, bloomed beautifully, and been trouble free. They have some other drawbacks as far as roses go -- no fragrance at all, for one -- but their ability to thrive and resistance to disease and bugs are two of their strengths, at least for me. My suggestion would be to evaluate where you have put them and move them if need be next April to a 25 dollar hole after pruning way back. Mad Gallica is the rose expert on this forum -- maybe she will add her thoughts, altho I doubt that she has any knockouts in her gorgeous beds.

    Bookmark   October 24, 2010 at 10:30AM
Thank you for reporting this comment. Undo

I'm flabbergasted, and sad for you, since my three have had phenomenal growth and keep blooming as late as December, last year. In fact, I don't think I even amended the soil in the back for my first two, and I have clayish soil. I do feed them every six weeks and water them one or two inches a week through August. They were so huge this year (I planted them in 2007) that I had to severely cut them back.

A rose expert here said some of her roses were killed or damaged by voles eating the roots over the winter. Could that be the problem?

    Bookmark   October 25, 2010 at 10:49AM
Sign Up to comment
More Discussions
What Trees in Your Yard Look Prettiest Now?
We tend to fixate on Spring blooms. What trees in your...
Cold or not, it's THAT time of year again!
The infamous Philadelphia International Flower Show is...
Seaweed as mulch
I am thinking of using seaweed as mulch or add to my...
How are you guys holding up in this "Snowpocalypse"??
Hi guys, haven't been posting much, but still lurk...
Climbing hydrangea question
Green gardener here. This is kind of a silly question...
c_ coy 7aMA
© 2015 Houzz Inc. Houzz® The new way to design your home™