Rosa ‘Ballerina’ – A hybrid musk rose, introduced in 1937, showing small single flowers in domed clusters. Each flower is light pink with a white center and yellow stamens. (Tom Karwin)
This year, with its unique weather pattern, roses are blooming in May, which is a little late for this very popular garden plant. We can forgive its adjusted schedule, and still enjoy the blossoms as in previous years.
Roses are members of the Rosaceae plant family of over 90 genera that includes woody trees, shrubs, climbers and herbaceous plants. Some of the family’s members produce edible fruits, such as apples, pears, quinces, apricots, plums, cherries, peaches, raspberries, blackberries, loquats, strawberries, rose hips, hawthorns and almonds. Other members include ornamental trees and shrubs, such as Pyracanthas (Firethorns), Photinias, and – no surprise – Roses.
The Rose genus includes 140–180 species divided into four subgenera.
The sub-genus that includes garden roses, includes too many varieties of roses to explore – or even to list – in this brief column. For a full exploration, see the references in “Advance your knowledge” (below). For a quick overview of this varied genus, the three broad categories are wild roses, old garden roses (once-bloomers), and modern garden roses (varieties developed after 1867).
Garden roses are available in tens of thousands of cultivars. The large and growing number of cultivars reflects the hybridizers’ responses to gardeners’ great appreciation for this plant.
Roses satisfy almost everyone’s concept of a beautiful flower. We say “almost” because some gardeners will have a different first choice, but he or she is likely to choose the rose as a close runner-up.
The appeal of this plant derives from the blossom’s color, form and fragrance, and the plant’s size.
Roses have a wide range of colors and blends, with every color in the white to yellow to red part of the color spectrum. lacking only true blue. Color variations within each blossom add to the appeal of this plant to rose aficionados.
The forms of rose blossoms are also quite varied. The American Rose Society defines “singles” as roses with four to eight petals. These have much appeal, but other popular forms are “semi-doubles” with nine to 16 petals, “doubles” with 17 to 25 petals, “full blooms” with 26 to 40 petals, and “very full blooms” with 41 to 100+ petals.
The fragrance of roses is an important attraction to gardeners as well as to pollinators. The fragrance or “rose perfume” is based on the essential oils in the rose’s petals. According to www.fragrancenet.com, roses have five key smells: myrrh, fruity, old rose, musk and clove. For lists of the most popular fragrances, search the Internet for “rose perfumes.”
The sizes of rose plants also vary over a garden-worthy range. All roses technically are shrubs, with the most common type being the bush rose, a rounded plant from 2-7 feet in height. Above that height, there are roses in the “climbing and rambling” class, both of which need support. There are also miniature roses and low sprawling ground-cover roses, both up to about 15 inches tall.
The accompanying photos from my garden suggest the wide variety of colors and forms of garden rose blossoms.
Care for your garden roses
Rose cultivation and care involves a great range of opinions and generates volumes of advice, with an emphasis on pruning. For useful references, see “Advance your knowledge,” below.
Still, roses famously care for themselves, and have earned such reputations as “cemetery roses.” These are often older varieties that have maintained healthy lives despite the absence of regular irrigating, fertilizing or pruning. This is not a recommendation to neglect roses in your garden, only to suggest that roses can grow on their own with remarkable persistence. This is particularly true of wild and old garden roses.
Most modern roses are propagated by grafting a desirable bloomer on a rootstock (which is closer to wild species) that brings vigorous rapid growth to the plant. That method yields positive results in several respects, but leaving such a rose to grow unattended would allow it to be taken over by “suckers” rising from the rootstock.
An option for gardeners is to favor “own root” roses, i.e., those that have not been grafted on a rootstock. This is not to encourage neglect of the plant but to appreciate the character of a pure variety and enjoy the freedom of not removing suckers.
Encouraging new rose blooms
When a bloom fades, cut the cane about a one-quarter-inch inch above the first five-leaf junction with the cane. If the stem seems weak or not well-placed, make your cut above the next five-leaf junction. New blooms will appear in a few weeks, depending on local conditions.
Another approach, a favorite of some gardeners, is to snap off the old spent bloom with your fingers.
Creating new rose bushes
A friend wanted to add Rosa ‘Polka’ to her garden but hasn’t found a source to buy this plant. The alternative: propagate a softwood cutting of this rose, which is already growing in my garden. Right now – late spring to early summer – is the ideal time to make a cutting. Here’s the basic method.
Select a flexible new, pencil-size stem with a withered bloom. Cut the stem to at least eight inches long, with four or more leaf nodes. Remove the bloom and the stem tip. Retain the top leaf and remove all the other leaves. Prepare the planting area, either a spot in the garden or a container with planting mix at least 6 inches deep. In either case, provide bright indirect light.
Insert the cutting into the soil with at least the bottom two nodes covered, and firm the soil around the cutting. Option: dip the bottom of the cutting into rooting hormone.
Keep the soil moist, but not soggy for up to two weeks while the cutting develops roots. Option: provide a light dose of rose fertilizer. Once the plant has established roots and shown new growth, transplant it to its new garden home.
Mark your garden calendar
The Monterey Bay Rose Society is planning a series of visits to local rose gardens, to provide opportunities for growers to show their achievements, and for other gardeners to appreciate the blossoms of well-grown plants and landscaping concepts. For planning purposes, visitors could identify varieties to add to their gardens, either because of singular appeal or desired contribution to garden design.
This column will include those events when the information is available.
You can also visit nearby large public rose gardens to see well-grown plants that are in peak bloom this month.
The San Jose Municipal Rose Garden is named “America’s Best Rose Garden.” Hardly a day passes when some species are not in full bloom, with more than 3,500 plantings and 189 varieties featured over 5.5 acres. For info: www.sanjose.org/attraction/municipal-rose-garden.
The Berkeley Rose Garden is a terrace hillside covered with 3,000 bushes and 250 varieties. This 3.64-acre garden includes a 220-foot-long redwood pergola whose preliminary design was suggested by the famed architect Bernard Maybeck. See berkeleyca.gov/community-recreation/parks-recreation/parks/berkeley-rose-garden.
The seven-acre Morcom Amphitheater of Roses has nearly 5,000 rose bushes flanking a 10-tier waterfall, with winding paths of tucked into a green canyon in a residential Oakland neighborhood. This 1930s-era formal garden is on the National Register of Historic Places and has been accredited by the American Rose Society. Visit friendsofoaklandrose.org/.
When you see roses that you would like to add to your garden, make a note in anticipation of bare root season (January through May), when roses are naturally dormant. Roses planted during their dormancy establish quickly in the garden and will flower in their first year. Some mail-order rose nurseries will accept orders throughout the year and deliver plants during bare root season.
Advance your knowledge
The Monterey Bay Rose Rose Society’s website (montereybayrosesociety.org/) provides advice and event information specific to the Monterey Bay area, including its display garden at the Santa Cruz County Fairgrounds. For information: montereybayrosesociety.org and check out its Facebook page: www.facebook.com/Montereybayrosesociety/.
Explore the website of the American Rose society (www.rose.org/) for articles and videos about rose cultivation.
For an overview of the genus Rosa, visit Wikipedia.org and search for “rose” or “garden roses.” For a quick read on the topic, visit simple.wikipedia.org/wiki/Rose.
Enjoy roses in your garden.
Tom Karwin is a past president of Friends of the UC Santa Cruz Arboretum and the Monterey Bay Iris Society, a past president and Lifetime Member of the Monterey Bay Area Cactus & Succulent Society, and a Lifetime UC Master Gardener (Certified 1999–2009). He is now a board member of the Santa Cruz Hostel Society, and active with the Pacific Horticultural Society. To view photos from his garden, https://www.facebook.com/ongardeningcom-566511763375123/ . For garden coaching info and an archive of On Gardening columns, visit ongardening.com. Email your comments or questions to email@example.com.