What is wrong with my knock out roses? (pic)

krisx2September 10, 2012

I planted 4 knock out roses from the farmers market in August of last year. This past spring, they looked great. I treated with Bayer 3-in-1, once in May, once in June. We sprayed with Sevin one time in June to prevent Japanese Beetle damage. I watered them regularly last year but not as much this year. We have had a good amount of rain this summer. All was well.

Since August, they have gone downhill. They have dropped a considerable amount of leaves. There is some new growth on them and they are flowering out, but they look bare. I have not fertilized since June.

I have 6 additional knock out roses in the yard that I planted two years ago. I bought these from a nursery. They got the same treatment as the farmers market roses. For some reason, they look great while the farmers market roses look bad.

There is no black spot or rust that I can see on the leaves. Does anyone have any ideas about what the problem is and if I can/should do anything to help it? Here's a photo -

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jerijen(Zone 10)

How much water have they had?
If these were in my garden, I would worry that the water-emitters weren't delivering enough water.


    Bookmark   September 10, 2012 at 12:59PM
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Did you plant the farmers market roses without spreading out the roots? In a pot the roses could of become root bound. If simply placed in a hole the roots may not spread into the neighboring soil,

    Bookmark   September 10, 2012 at 2:44PM
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michaelg(7a NC Mts)

The happy set has been in the ground two years, the unhappy set one year, so the unhappy set has shorter, shallower roots and would be more susceptible to drought and heat. Expanding on Henry's point, potted roses purchased in August may be pot-bound with circling roots. They have been in the same pot for 5-6 months.

    Bookmark   September 10, 2012 at 3:28PM
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I don't think we spread out the roots when we planted them. This could very well be the problem. Will they recover? My plan was to let them be until spring, then prune them down and give the new growth a chance to fill in. Is this a good plan?

It was very hot here in Raleigh, NC, reaching 100 degree temps from about May - July, then cooled off in August. The heat may have been too much for the shallow-rooted plants. The water situation should have been decent between rain and us watering but the roses may have suffered because I figured they were established, and I wasn't giving them any special attention.

    Bookmark   September 10, 2012 at 3:41PM
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You cant always count on the same plant, planted far from one another, to react to growth habit the same way.
Like children, each has it's own way. The soil is/likely not of the same structure and therefore, takes up moisture in a different way. Cultivation should be done shallow...to not bother the roots. Instead of fertilizing in a hit and miss way, try to feed the plants on a scheduled program....every 2 weeks with a water soluble type, or as the label directs with a granular type. Work in with your hands....you can usually feel the soil at the plant's base and tell if it needs water.
Roses....its the old story---do not like wet feet...they don't appreciate heavy watering; rather regular watering is better with good drainage.

If you feel you have damaged areas, cut that back to good growth to an outward facing bud. Any damaged stems cut it out. Don't leave damaged or weak canes to spread whatever is causing a problem.

Keep watering to mid morning or late afternoon to let the sun dry them.
Spray only the leaves and/or the soil at the base of the plant. Spray can be a general purpose one or one designed for specific rose problems and that can be done too on a regular basis and not wait for a problem before you get to it

    Bookmark   September 10, 2012 at 11:25PM
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Will root bound plants recover?
My answer: yes, no, and maybe.

Since you have 4, I would suggest digging one up (possibly the smallest) in late fall to check the root situation. If O.K. I doubt if the replant will set it back very much. If there is only a root ball, spread out the roots before replanting.

    Bookmark   September 10, 2012 at 11:34PM
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diane_nj 6b/7a

Also, rock the plant to see if it is firmly in the ground and hasn't been shaken loose by critters or wind. But, I also think it isn't taking up enough water.

    Bookmark   September 11, 2012 at 5:09PM
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Cut it to the good growth. It is having a moment. I have 2 gorgeous knockouts in my front entrance way. I have clay soil and I NEVER water anything in the front (mostly because I don't use that door). My KOs are HUGE. I have never put fertilizer of any kind on them. I whack em down in late fall so I can get up the darn sidewalk. I can't control them but they are lovely. OK.. I ramble. Cut em and give em a chance to do what they do best.

    Bookmark   September 11, 2012 at 9:11PM
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Thanks so much for all of your feedback. It is enormously helpful. I thought of cutting them back but is it okay to do this now when are having cooler temps? It is getting down to about 55 at night and up to 85 during the day. I am in Raleigh, NC so we have milder winters but usually it cools off by November.

    Bookmark   September 12, 2012 at 2:30PM
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pembroke(6--Louisville KY)

I have one knock out rose that didn't fare very well because of drought in my area. As soon as it started raining and the weather got a little cooler that rose started blooming and looking better. Pembroke

    Bookmark   September 12, 2012 at 3:41PM
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michaelg(7a NC Mts)

I wouldn't prune off much if any healthy wood at this time. Heavy pruning could force new basal growth that might not make it through winter, if it drops below 10 degrees.

    Bookmark   September 12, 2012 at 5:18PM
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