Rose care and info for Fall in the Bay Area
By Royal Krieger, Morcom’s Rosarian
September and into October is usually our Bay Area’s “Indian Summer,” a period of warm weather that often brings increased bloom. The coloring of some roses may be somewhat different than earlier in the year. The sun, being lower in the sky, casts a different light angle which influences color.
If needed, now is the time to do an end of year fertilizing with no nitrogen, some phosphate, mostly potassium. However, if adequate fertilizing was done when the winter pruned roses first leafed out and a second fertilizing around 4th of July was done, generally there is adequate potassium in the soil so this final fertilizing may not be needed.
If I have not been cleaning rose beds of debris I do so now. It is important to remove diseased leaves on plants as well as on the ground. This will pay disease reduction dividends next year. I also remove dead and weak canes and “open up” the plants. I want to allow more air through the plant for disease reduction. However, this does not mean completely removing all canes or growth in the center of the plant. This is especially true for floribunda class roses. I mainly just decrease the interior growth density.
Regarding grafted roses, it is not uncommon for these roses to have a cane growing from below the bud union starting around seven to nine years of age. These unwanted canes are called “sucker shoots” or “suckers.” It is important to remove these suckers because they are actually new canes emitted from the root stock graft and can rob the grafted rose of nutrients and in time may seriously weaken or kill it.
I avoid pruning off suckers at their base because this just stimulates a return. Instead, I pull down on the sucker at its base. With luck this will tear out the sucker and usually no sucker will reappear. Sometimes I have to dig down into the soil to be able to pull down. If suckering is a major problem I consider replacing the plant.
So why do growers graft roses rather than let a cutting develop as “own root?”
1) Some roses do not do well on their own roots and need the vigor of root stock to develop a larger and more robust plant,
2) Using root stock a grower can develop the rose for market in as soon as18 months versus three years,
3) Some rose varieties are difficult to root from cuttings. Generally ‘Dr. Huey’* or a ‘Multiflora’ is used for root stock in northern climates and ‘Fortuniana’ in most southern climates.
September is often the time I evaluate my garden to determine what I’ll do later in the year. This includes deciding which roses to remove or transplant to a better location, easier to determine now when the garden is still in bloom than November when fairly spent.
Finally, this is a good time to clean and sharpen tools if I haven’t been doing so. I find that removing pitch from loppers and hand pruner blades is easier by rubbing with an auto bug remover or good old WD40. I use a fine grit sandpaper for especially stubborn pitch removal.
Happy gardening.
* Dr. Robert Huey fought in the Civil War on the Union side, was captured and escaped. After the war he became a dentist in Philadelphia and an avid rose hybridizer and researcher. A fellow rose hybridizer/researcher created-a-once a year blooming five petal deep red vigorous climbing rose and named it in Huey’s honor. During the 1950’s some of the major rose growers tested various roses for use as root stock. Dr. Huey was found to be the best root stock for California grown roses.