Roses for Florida
Looking for a low-maintenance rose for your landscape? Researchers from the University of Florida/IFAS may have the answer. A statewide study recently looked at rose performance in order to determine which rose varieties will perform best in Florida with minimal inputs.
The study looked at twelve rose varieties that were grown using their own roots (they were not grafted). The research beds were amended with Black Kow (a composted cow manure), mulched heavily, and fertilized twice a year with a 15-9-2 Osmocote 6-month fertilizer.
The plants were irrigated with drip irrigation; this keeps water off the leaves and discourages fungal problems. Each plant was watered with one gallon of water two times a week. No pesticides were used on the test roses and each plant was pruned only once a year during the dormant season.
For a little background on how roses are classified, roses are often divided into two groups: old garden roses (OGRs), also called antique or heritage roses, and modern roses. Modern roses are varieties that were introduced after 1867, while old garden roses are those that came before. Roses are further divided into classes. Shrub, hybrid tea, polyantha, grandiflora, and floribunda are some of the classes of modern roses that are most common in Florida.
Some common classes of OGRs are China, tea, and Bermuda mystery. Bermuda mystery roses have an especially interesting history. These roses have been grown in Bermuda for at least a century and are thought to be old garden roses brought to the island by European settlers. Their true names are unknown, so they have traditionally been named after the owners of the gardens in which they were found, such as the 'Miss Atwood' and 'Emmie Gray' roses. As a group, they are interesting for Florida gardeners because they tend to be nematode- and disease-resistant, as well as tolerant of hot and humid conditions.
Gardeners in Florida often contend with different challenges than people in the rest of the country. Rose disease problems, such as black spot and Cercospora leafspot, are amplified here by the heat, high humidity, and rainfall. Black spot and Cercospora cause defoliation and a general decline in rose bushes that are untreated. Roses are also a favorite of chilli thrips, tiny insects which feed on and distort leaves and flowers. To date, chilli thrips are most problematic in Central Florida.
Selections for Florida
Selecting the best rose means looking at how well it deals with our particular climate and soils, as well as our insect and disease problems. For growing roses in Florida, the study found that the best performers were 'Mrs. B. R. Cant', 'Spice', 'Louis Philippe', and Knock Out®.
'Mrs. B. R. Cant' – This OGR is classified as a tea rose. With a medium pink color and 3- to 5-inch double blooms, this rose bush gets quite large, growing to between 8 and 10 feet tall and wide in the Florida test gardens. The lightly fragrant blooms from 'Mrs. B. R. Cant' hold up quite well as cut flowers. This particular rose bush has intermediate susceptibility to black spot and cercospora leaf spot, and low susceptibility to chilli thrips.
'Spice' – This Bermuda mystery rose is a great choice for Florida gardens. With 3-inch double flowers that start out white and turn the lightest pink, 'Spice' is a smaller rose shrub reaching about 4 feet tall and wide. For all its virtues, 'Spice' is also highly susceptible to black spot, intermediately susceptible to Cercospora leaf spot, and susceptible to chilli thrips. However, this rose perseveres through these problems and maintains a compact form and nice foliage year-round. 'Spice' likely gets its name from the peppery fragrance that comes from the continuously present flowers.
'Louis Philippe' – Another OGR, 'Louis Philippe' is a winner throughout the state. This China rose is also called "Florida Cracker Rose" and is one of the few crimson roses that does well in Florida. The charming 2- to 3-inch double blooms of this plant have a lovely fragrance, making them a treat for multiple senses. 'Louis Philippe' is resistant to black spot and chilli thrips, making it particularly good for many Florida gardens. 'Louis Philippe' can get somewhat large, reaching 7 to 8 feet, and can be a bit gangly in the eyes of some.
Knock Out® – The only modern rose on this list, Knock Out® roses have become popular nation-wide due to their resistance to black spot. These single-petaled roses are about 4 inches and come in a beautiful cherry color. While they are resistant to black spot, they are highly susceptible to Cercospora and intermediately susceptible to chilli thrips. This rose bush continuously flowers and the blooms make great cut flowers. With a nice form, this shrub grows to about 4 feet and will look lovely in many landscapes. For added interest, the new foliage of Knock Out® is maroon, turning green as the foliage matures.
Roses, particularly OGRs, need time to start making an impact in the landscape, so don't fret too much if your roses start off slow. It is said that old garden roses "sleep the first year, creep the second year, and leap the third year." So while it may take time, waiting for your roses to reach full stride can really pay off.
When caring for your old garden roses, be sure to prune lightly; tea roses in particular will not appreciate the vigorous pruning given to hybrids and will often "sulk" if over-pruned. So don't prune unless you have to—and remember to mulch your roses as well.