Pruning Knock Out Roses
Knock out roses are gaining popularity because they are easy to care for and fairly disease resistant. One of their selling points is that they are “self cleaning” meaning the petals fall clean, and while that may be true this article discusses why you should regularly deadhead them and explains the simple process of pruning Knock Out roses annually.
Deadheading Knock Out Roses.
During the growing season it’s worth your time getting rid of any spent flowers by deadheading the rose bush. Deadheading on a regular basis will help the plant maintain its compact bushy habit and encourage prolific flowering. It is promoted as “self cleaning”, however, lightly pruning knock out roses is beneficial to the plant. If you don’t remove the spent flowers, they will develop into rose hips and the energy the rose uses in forming these hips greatly reduces flower production.
If you like the look of the orange coloured hips on the rose as some do, then just realise that you wont get masses of flowers on your knock out rose. When deadheading you just cut the spent flowerhead back a couple of inches – nothing too severe during the growing season as the flowers bloom on new wood. This encourages new growth and an abundance of new flowers. You also want to trim any wayward branches to help keep its shape.
When to Prune Knockout Roses
Knockout roses benefit from an annual prune. For those living in a warmer climate zone, for example in zones 7+, you’ll want to prune knock out roses in mid to late Winter. For those living in colder climate zones, early to mid Spring once the frosts are over, is more ideal. Though you are always better off asking a local plant nursery, local garden club or rose society the ideal rose pruning time for your particular location, so you get the timing spot on.
Pruning Knockout Roses
Because the knock out rose is a landscape shrub rose, it doesn’t need the detailed pruning that some other species need. Remove any dead or damaged wood and if there is a lot of overcrowding of branches in the centre of the rose you can remove a few of these branches if you wish, to open the rose plant up a little and improve air circulation. This is not necessary however, and some people are happy to leave them as is. It won’t hurt the plant if you don’t.
Knockout Roses Pruning
You can easily prune knock out roses annually by reducing their height by half to two thirds. This way you will end up with a knockout rose that is around 12-18 inches high after pruning. You don’t need to fuss with each stem individually, cutting to an outward facing bud either; you can use hedge trimmers or loppers to prune the knock out roses down to size.
Some folk don’t prune down to 12 inches as they prefer to have taller knockout rose bushes so it’s up to you. You can afford to experiment a little with this plant so one year you might prune it 12 inches and see what height you end up with at the end of the growing season; the next annual prune, you could prune a little higher; 18 inches or more, and see how tall they grow from that pruning height.
There’s no hard and fast rule with this easycare rose, though knockout roses do benefit from an annual prune. After experimenting, you can just decide on the pruning height you prefer.
Every couple of years remove some of the older woodier branches at the base of the plant to encourage the development of new branches which will produce much better blooms. Doing this will keep your knock out rose blooming for many years. Pruning Knockout roses is an easy garden task and one more reason this rose is so popular with gardeners.
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I have 3 knockout rosebushes. One is growing in a sunny location, it is growing tall, some of the stems are really thick an some are brown like there dead, but new growth and roses seem to flurrish, they really bad.
Hi Jean
If the rest of the rose bush is growing well as you say with new growth just cut out the dead stems. Also have a good look at the plant to check for the presence of any pests or diseases that may have caused the dead stems in the first place. If present you may have to spray with a suitable pest or disease treatment.
I planted my first knockout roses this summer….I live in Tennessee….the plant appears very healthy and gets afternoon sun mostly….I have been “deadheading” it regularly…the blooms are beautiful….but it is starting to produce alot of red leaves that appear healthy as well….what causes this and what should I do about it if anything….thanks in advance!
Hi Joe
as new leaves develop on roses they can appear reddish in color until they grow out and green up. This sounds to me like what is going on here as you say the “red” leaves are healthy. Enjoy your first season of knock out roses.
I was not able to prune my knock out roses in late winter as recommended due to my husband being in the hospital off and on all summer. Now my knock outs are very tall and leggy. I really want to cut them back because I see a lot of stem at the bottom with no foliage. Is it ok to prune them even though it is late September?
If you live in the southern hemisphere and are in a warm climate you could still prune them now but I wouldn’t be too severe with it, maybe just reduce them by one third. If you live in the northern hemisphere it would be fall and it may be best to leave it if you are in a cold zone as they would be starting to slow down their growth as they approach dormancy. If in a warm zone though, I would still give it a shot, but again, I’d only prune a third off the plant.
I planted a single double knock out rose this Spring. I live in Missouri. It has grown so huge that it’s overtaking my landscape. I want to cut it down so it goes more with the rest of the plants. Is it okay to cut it back now (Oct) or should I just wait until late Winter or early Spring and worry about managing it next year?
Hi Joan
I’d be interested to know how “huge” your knock out rose has grown in your area and what you’ve been feeding it:) Missouri has a USDA climate zone ranging from 4 to 7, so I’d wait to cut it back until early spring after the last frosts. Prune it down to about a foot then and see how high it grows through summer. Pruning that low might keep it from growing too large. Knock out roses usually grow 3 to 4 foot in height and width but if this is too large for your landscape you may want to either replace it with a lower growing landscape rose or you could just give it a light prune every few weeks during the growing season. This will help to keep it to the size you want, but you’re only going to get a flush of flowers every few weeks if you choose to to this.
Hi,
I planted 4 (5 gal) double knockout rose plants this past July, and had enjoyed blooms since.
(I did not know that it needs to be deadheaded or pruned. Just started gardening…)
I have read different articles of ways to deadhead but I am not sure which way would give the best result, ie a couple of inches from the spent flowers or 4rth of an inch next to the first 5 leaf of a stem, etc.
I also do not know if I should prune in the first year since I want to keep th current height(3ft), but if needed, not sure whether to prune now or wait mid to late winter (Feb?).(I live in Georgia)
Hi Rossana
with these type of roses you don’t need to be overly concerned with how you deadhead them. A couple of inches from the spent flowers is fine, even 3 inches would be fine if you are trying to keep the plant at a particular height – you don’t have to be too particular. I would prune them in their first year though, as in your area knock out roses can grow quite tall, and you mention you want to keep them around the 3 foot mark.
Prune them next February down to about 18 inches in height, and then see how tall they grow through the season. If they grow taller than the 3 foot you prefer, you might want to prune them down to 12 inches the next year you do the annual prune. The wholesalers of these roses reckon they will usually triple their pruning height during the growing season, but just experiment the first time with 18 inches seeing it’s the first yearly prune and if it gets too tall, prune down to 12 inches the next time around. With regular deadheading of the spent blooms during the growing season, you can usually keep them at around the 3 foot mark at any rate.
I live in middle Tennessee what month do I prune?
Hi Sandra
March would be the time to prune in Tennessee, after the last hard frost.
I am in Raleigh, NC when should I prune my Knock Out roses?
Thanks
Joy
Hi Joy
the best time to prune your knock out roses in Raleigh North Carolina would be March, after any hard frosts and when the buds begin to swell and break their dormancy.
I have 2 knock out bushes planted side by side. One seems to be growing much larger than the other. Should I move one to give the other more space? Also, when should I prune in Illinois? Thank You.
Hi Sharon
How far apart have you got them planted now? Knock out roses should be planted about 3 feet apart, so if they’re planted any closer than this it may be a good idea to move it. The best time to do this is when it’s dormant, so either transpant it in fall as it’s going into dormancy to establish some roots before winter or wait until spring as it’s just coming out of dormancy and after any heavy freezes if you live in the colder climate zones of Indiana to do this.
If they are already planted 3 foot apart, then it’s up to you; you can either move it a bit further apart or when deadheading spent blooms, cut a few inches further down the stems than you normally would to keep it at the height of the other one.
In Illinois the best time to prune knock out roses is in spring; when the forsythias start to bloom is a good rule of thumb.
I live in Indiana, when should I prune my Knock Out roses?
Hi Kelly
the best time to prune your knock out roses in Indiana is in late March/early April after the last freeze.
I am in Silver Spring, Maryland, when should I prune our Knock Out roses?
Hi LInda
Late March or early April is the best time to prune your knock out roses in Maryland; around the time the forsythia blooms.
I cut my bush down to 12 inches in November,,,Will itreturn in the spring? Will be a burlap bag protect it thru our harsh winters..I am in the Boston area of Massachusetts. I’m new at this and I dont really know if my bush is a knock out rose but I’d liek to plant one in the Spring…Thanks Jeni B
Hi Jeni
unfortunately you pruned your rose way too early; the best time to prune a rose in your area is late April, after the last frost. The best thing to do so it survives the harsh Boston winter and returns in spring is to use one of the collars I suggest here and pack it with mulch or soil or leaves. You may need to join two together if the rose is largish. If you can’t get the collars then just mound soil or mulch to a height of 12 inches around the plant. Remove the mulch and rose collar in spring. Let me know how it survives the winter following this advice. I’d be interested to know if the too-early pruning did it any great harm over the winter if it was mulched heavily. Good luck with it
We live in Atlanta and planted a number of these beautiful bushes last season. Given our climate zone,when should we prune? They need to be cut back substantially, but we don’t want to damage them.
Hi Scott
given your climate zone in Atlanta, you should prune your knock out roses in early March. You can safely prune them down to about 18 inches if you like, without causing damage to them.
I live in the Corpus Christi Tx area. When should I prune my knock out roses?
Hi Shirley
February is the best time to prune your knock out roses in Corpus Christi Texas area
This will be my second year with my ko roses. The problem I’ve been having is they are all scragly, only growth mainly at the top of the branches. I pruned them a little during the growing season but they didn’t fill in.They were repeat bloomers and are still producing. I want a prettier fuller bush. What can I do to make this happen? ( Panama City Fl.)
Hi Amber
the reply I have for you turned into an article on scraggly-looking knock out roses and is located here.
Hi,
I live in Florida in The Villages an hours drive south of Ocala. I think we’re in zone 9 but not totally certain. I have several double knockouts in their second year of growth and doing well. We do get frost sometimes in the winter & even had a freeze last winter. When is the best month to prune?
I also have a knockout rose tree that now looks a little wild & not as compressed &full as I feel it should. As a note this tree was adopted by a mama bird & she made her nest in it this past spring & I did not notice it until later in the summer when the center of the tree started to look a little bare & discovered the used & abandoned nest. How should I go about trying to trim this tree back so the form & size of the ball will look good?
Thankyou
Hi Joan
you’re right, you are in zone 9 and the best month to prune knock roses in your area of Florida is February.
With your knock out rose tree, give it a decent prune back in February, measuring about 12 inches out from the center all the way around, pruning it into a ball shape. That should allow it to bush out again once growth commences.