Evergreen roses in a zone 6/7 winter

Climate conditions this year caused more leaf drop than in any previous years. Usually I depend on dormant strength Limesulphur in early January to force leaf drop, but this year an early very cold spell in December led to deleafing, and warm temps in January weren’t enough to cause leaf out before temps in the lowest teens for an extended period in February.

Some of my evergreen roses have retained their leaves through this period.

Rosa laevigata doesn’t seem to have dropped many leaves. Temps down in the species beds were probably upper single digits…laevigata has simply ignored the cold.

R. wichurana has also kept its leaves, although it’s a ground hugger so that might be easier to explain.

R. bracteata has lost some leaves, but canes added late last year still have bright green leavs.

R. multiflora watsoniana has its leaves; for something that looks as ill as it does, I wouldn’t use this for squat.

R. sempervirens is as advertised and may have even grown a bit since fall.

R. virginiana has leaves, but isn’t heavily leafed out. Same with R. x. fortuniana.

And among other roses, I have several clones of Old Blush. One from a cold )top of a mountain) cemetery in Virginia is still leafed out. Others from commerce are less so.

Laevigata continues to surprise me.

Ann, the more I think about it the more I am inclined to believe that we as breeders should make an effort to breed roses that are either evergreen OR deciduous.

Many of the problems we experience with disease is in my opinion a direct result of incomplete or partial senescence.

Robert,

I agree. And the more often a plant replaces its leaves in a year, the less energy goes into the overall strength of the plant.

I think this may be a long term potential for dealing with Rose Rosette Disease as well. I have a Brother-in-law who’s a PhD in Microbiology; his solution is to find RRD resistant roses and genejockey resistance into new roses. I try to tell him the money isn’t there, but he comes from pharmaceuticals and limited funding isn’t in his vocabulary.

RRD comes in and is a problem when the mites can find either active apical meristems or active leaf axilary buds so that the mites’ very short feeding stylets (ten microns) can reach into undifferentiated tissue. If the plant is not putting on growth, year round, then there is a real break in disease transmission.

Mite populations surge at certain times of the year-sometimes that’s when roses are regrowing leaves lost to summer fungal problems. (RRD also spurs growth year round- a multidedged sword of a problem.)

I’ve never seen RRD. I’m sure we in CA will eventually experience it. Scary stuff!