Mutant rose bush?

March 6, 2009 2:53 PM

What's up with my rose bush?

One of our "Knockout Rose" bushes has sprouted a large and straight runner that has blossomed in less than two months. The leaves and stem are much larger than the older part of the plant, and it just looks a bit weird. What happened here? Was the rest of the plant a graft and this is the original stem re-establishing itself? It does look rather unsymmetrical now. Would I be hurting the plant if I nipped it? (Please excuse the poor light balance in this picture)

posted by Burhanistan to home & garden (7 comments total)

According to some quick google searching, knockout roses -do- have a root/body graft. This would make sense since they seem to be advertised mostly for disease resistance, and roses which do well root-disease wise are not always the most scale/rust/whatnot resistant above-ground.

Sucker offshoots like the one you've got will make it harder for the upper graft to flower, so I'd recommend removing it. You want to get as close to the main stem/branch/root (whatever it's growing out of, basically) as possible, as if you leave a bud behind it'll just shoot right back up. Cut it off flush, and hope for the best.
posted by Phineas Rhyne at 3:30 PM on March 6

Can't quite say from the photo, but roses and other "rambly" plants like raspberries tend to put out canes - fast growing thick shoots that go looking for something to sprawl on. In the tropics, bougainvillea is a common one to do that. You have a nice tidy bush and then *bam* a 3 meter tall cane goes shooting off into the sky looking for a perch. It could also be a cultivar reverting to type. It is not necessarily a graft (though I'm not familiar with that variety and it could well be): variegated cultivars in particular have a tendency to produce a normal-leaved shoot from time to time, don't ask me why. Bottom line, no harm whatsoever in cutting the cane back if you don't like it.
posted by BinGregory at 3:40 PM on March 6

It's a little hard to tell from the photo. Is it the same kind of rose as the rest of the bush? If so, welcome to spring, roses are weird, flowers are pretty. If it's a different kind of rose, it's from the rootstock.
posted by desuetude at 4:10 PM on March 6

Tread carefully, grasshopper!

If the growth came from below the graft, and is a "basal" or "sucker shoot" of the root-stock, then DO prune it. With a sharp knife and extreme prejudice. If, however, it has grown from above the graft, it is likely a "water shoot" and should, according to rose expert types, be greeted with glad cries, pampered and treasured, and never ever pruned.

You might have more success googling for some of these terms. With the different foliage, I would say it is a basal sucker, but - I Am Not A Rose Expert, IANYRE, etc.
posted by Catch at 4:13 PM on March 6

Oh, yes, and water-shoots DO tend to be sudden, vigorous, and exuberant so that doesn't help distinguish them from t'other type, and at least your bush is 'normal' in that regard.
posted by Catch at 4:17 PM on March 6

Looks like the same flower to me- shoots like this are normal, both from rootstock or the named variety. It looks stronger and healthier than the rest of the plant, so if it's not from below the graft, keep it. You want strong, thick canes. Prune it to an outside bud if it's really bugging you, but don't cut it all the way off, especially since "Knockout" blooms on new wood.
posted by oneirodynia at 5:06 PM on March 6

Thanks for all the considered advice. The mutant just let loose with around 8 more very fragrant and large blooms so I'm a bit reluctant to prune now even though the bush looks imbalanced. Next time my mother (family botanist) comes over we'll take a close look and make ijtihad then.

Also, I just planted another rose bush in our backyard in honor of Mawlid an Nabi.
posted by Burhanistan at 7:25 PM on March 9