The main problems with roses locally are not related to climate, soil, insects or disease. Warm and semi-arid climates of California happen to be some of the best places in the World for roses. Sure, many roses have problems with insects such as aphid, and diseases such as powdery mildew, but primarily because such pathogens proliferate among roses that are not pruned properly.
Yes, the main problems with roses are a direct result of improper pruning. Without adequate pruning, roses become overgrown thickets that shelter the pathogens that afflict them, but also lack the vigor to be resistant to damage. Like so many other domesticated plants, they were bred for maximum production of unnaturally big flowers, at the expense of natural resistance to pathogens.
Pruning eliminates superfluous growth and improves air circulation, which interferes with the proliferation of most types of pathogens. Most pathogens overwinter in fallen foliage that should get removed in the process. Pruning also concentrates growth of the next season into fewer new stems, which stimulates vigorous growth that hopefully grows faster than the pathogens that infest it.
Roses should be pruned while dormant in winter, after defoliation, and before buds start to swell at the end of winter. Hybrid tea, floribunda and grandiflora roses should be pruned back to only about three to six canes that grew from the base during the previous year. Older canes should be removed. Remaining canes should be only about two feet tall, and cut just above a healthy bud. Any growth below the graft union (where the basal canes originate) are genetically different suckers (from the understock or rootstock) that must be removed.
As growth resumes in spring, well pruned plants will produce fewer stems and blooms that are significantly more vigorous than those of inadequately pruned plants. Overgrown and inadequately pruned plants must spread their resources thin amongst more but significantly weaker stem growth that is much more likely to be damaged by pathogens. Aggressive pruning now pays off later.
Winter is for pruning. Any good native of the Santa Clara Valley knows that. It starts as soon as the first deciduous fruit trees defoliate and continues to the last minute rush to finish before the buds start to swell at the end of winter. It may seem like there would be no last minute rush now that all the orchards are gone, but there is so much in landscapes to prune that prioritizing and scheduling pruning takes a bit of effort. Just like we know that apples and pears can be pruned slightly later than apricots and prunes, in the landscape, we know that sycamores might be delayed until the birches are done. Naturally, I feel compelled to prune the flowering cherries and fosythias, but am almost content to wait until after they finish blooming in early spring. Of course, I cringe as I write this.
Now, before I commence with my rant and long list of problems with this picture, I should mention that this seemingly abused rose tree does seem to be appreciated. All the roses in this landscape seem to be very healthy, and they bloom constantly between spring and autumn. Their performance suggests that they are regularly fertilized and deadheaded.
Autumn really is the season for planting. That is the general rule. One generalization about general rules is that they generally do not apply to all of the specifics. In other words, there are likely certain exceptions. In this case, there are some types of plants that should not be planted in autumn. The next best season for planting is probably winter, which happens to be ‘bare root season’.
They compare to more traditional roses like instant coffee compares to real coffee. They are too easy and cheesy. However, even instant coffee can be rather good as long it is not expected to taste like the real thing. Likewise, carpet roses do not produce big and fancy flowers on long stems for cutting, but they have other attributes that are advantageous in the landscape.
Winter is no excuse to be less diligent in the garden. It would seem that gardening would be less demanding because there is less going on, and so many plants are dormant. However, dormancy is precisely why there is so much to do through winter. Bare root plants and bulbs are planted because they are dormant. Fruit trees get pruned because they are dormant. Now it is time for roses.
Christmas tree lots at nurseries come and go at a good time. Cut and live Christmas trees become marketable just as retail sales of other items is declining. Although autumn is the best season to plant many things, not many of us want to be out in the garden as the weather gets cooler. As Christmas trees get sold and relinquish their space, bare root nursery stock becomes available.