update on the latest rootstock options
for growing your roses
Most people who grow roses know that their rosebushes are budded or grafted onto the rootstock of another rose. Basically, a bud‑eye is taken from the desired rose plant, such as 'Peace', and grafted to the stem of a growing rootstock plant, below the bottom set of leaves. After the bud‑eye produces adequate growth, the top of the rootstock plant is cut away entirely, leaving 'Peace' growing on the roots of the understock.
There are several advantages to this method of propagation, for both professional and amateur growers. To begin with, it is the most efficient and cost‑effective way to produce a large number of roses of a single variety. Many growers sell up to 5,000 plants of a new cultivar; if it is an AARS Award Winner, the introducing nursery needs to have 250,000 bud‑eyes available to all participating AARS nurseries two years before introduction. Budding requires only one bud-eye per plant, whereas each cutting would require 3 or 4 bud‑eyes. Also, budding tends to improve vigor (more so with the older varieties of the 1940s and '50s), and produces more uniformity in the quality of the plants. In backyard propagation, budding is considered to be an easier means of reproduction than by rooting cuttings, according to Justin Ekuan of Dana Point, CA, a rosarian who has spent many years experimenting with a variety of rootstocks. Also, he says, "There's no question that grafted roses are far superior in size and bloom production – at least twice that of own‑root roses."
The most commonly used rootstock is the Climber 'Dr. Huey'. Tom Carruth at Weeks Roses says that, except for the Miniatures, MiniFloras, and Shrubs that are grown on their own roots, "we use 'Dr. Huey' exclusively. It propagates easily, it has a long budding season, the plants harden off and ship well, they store well when bare‑rooted, and the general adaptability to the broad area of climates and soils that we ship to is pretty good." Also, it does well in the growing fields of Wasco, California, which produce about 80% of this country's roses (other than Minis and MiniFloras). Unfortunately for the rosarian maintaining rootstock in the garden, 'Dr. Huey' tends to mildew (a trait that is not passed on to the budded rose).
For standards, or tree roses, some nurseries use a separate inner stock, such as 'De La Grifferaie', for the stem between 'Dr. Huey' rootstock and the grafted rose. However, most nurseries now use a full-length cutting of 'Dr. Huey': for a 36" tree, a 38" cutting is stuck in the ground, staked, and covered by a long, plastic sleeve (for protection while rooting), then de-thorned and de‑eyed by hand, and grafted twice (on opposite sides of the cane) with the desired cultivar.
Multiflora is not used much in California as it is inclined to pick up salts and is not "happy" in alkaline soil. Phil Edmunds, formerly of Edmunds Roses in Oregon, said he used 'Burr's Multiflora' for locally grown roses because it is a good, all‑around fast performer for their shorter growing season; it's winter-hardier than 'Dr. Huey', it grows faster, and roots quickly in Oregon's colder climate.
Hortico in Canada uses 'Rosa Multiflora' seedlings for most of their stock, one seedling per grafted rose, in order to minimize the incidence of mosaic virus (a disease that is transmitted from the rootstock to the rosebush, or vice versa). Chances are only 1 in 10,000 of getting an infected seedling.
Ekuan states that Multiflora is very sensitive to virus; when an infected bud‑eye is grafted onto it, even the mildest case of virus will show substantial infection. He uses it to test questionable bud wood. 'Fortuniana' is an understock that was originally used mainly for Florida gardens. According to Keith Zary of Bear Creek Gardens, "Fortuniana is a very vigorous rootstock, but extremely cold sensitive and doesn't respond very well to freezing weather; it dies quickly."
However, researchers at the University of Florida have concluded that 'Fortuniana' is resistant to gall, nematodes, and stem dieback, as well as many root diseases, performing better than all other rootstocks tested. 'Fortuniana' is also purported to live and produce years longer than any other rootstock.
Kitty Belendez, Southern California Master Rosarian, orders virus‑free 'Fortuniana' cuttings from the University of California at Davis to root them and chip bud her favorite varieties of all types of roses, including Minis and Minifloras. She says that plants grown on 'Fortuniana' do very well in her sandy soil: "They grow really fast, the bushes get really big, and they produce lots of blooms."
For these reasons, many Exhibitors prefer to grow 'Fortuniana' rootstock roses. Cool Roses and K&M Roses, located in the warm climes of the south, grow and promote 'Fortuniana' grafted roses, touting enhanced performance in more moderate climates. 'Manetti', a light pink Noisette, was once the preferred rootstock of some growers, but has been largely replaced by the old favorite, 'Dr. Huey'. Wayside Gardens, whose roses are grown in California, now uses 'Dr. Huey' on everything (English Roses, Old Garden Roses, Hybrid Teas, etc.) except for some Shrub Roses and a few varietals which are extremely vigorous on their own roots.
And Edmunds Roses, which once used indexed (virus‑free) 'Manetti' for their California grown plants, was bought by the Jung family of J.W. Jung Seed Co. in 2007. With all of their growing fields currently located in California, they now grow all of their budded roses on 'Dr. Huey'. 'Odorata' was a favorite of hybridizer Joe Winchel until his source‑plants succumbed to Downy Mildew. 'Odorata' works well for "bench grafts", where the graft is done at the same time as rooting the cutting of the rootstock. Justin Ekuan claims it is a vigorous rootstock but "it suckers like crazy – the champion!" And it is susceptible to crown gall.
Ekuan's current favorite is a hybrid multiflora, 'De La Grifferaie', which he acquired as a sucker from a tree rose. He claims that it does not sucker if the bud‑eyes are properly removed. It has big, thick canes that bud easily (the skin separates from the wood "like butter"), few thorns, and it roots fairly well; "You could root a 7-foot cane!"
The rootstock that Joe Winchel preferred is known as "069", a winter‑hardy variety developed by Griffith Buck. The plants are disease‑resistant, thornless, and grow quite tall. Winchel said, "I would like it even better if the whips [canes] got bigger in diameter – its maximum size is pencil thick."
Justin Ekuan discovered a vigorous root system on the Mini 'Pacesetter' when trying to remove the plant. When used as an understock for the Hybrid Tea 'Lynn Anderson', the grafted plants did as well as those on 'Dr. Huey'. He also tried the Floribunda 'Iceberg' (which had survived a flood in his garden), but found it to be inferior as a rootstock.
Whatever rootstock is used, once the plant has been budded and is growing on the understock, it takes its inherent qualities from the grafted cultivar. No rootstock can improve disease resistance or intrinsic vigor; if a cultivar is inferior, it will not do well on any rootstock.
Although some cultivars do better than others on certain rootstock varieties (e.g., 'Odorata' is said to work better with yellows and yellow-blends than red-family roses), generally, rootstock is chosen for its performance (before it is grafted) in the region where it is grown and propagated. Even with so many choices, Carruth says, "You'll find there's no perfect rootstock, just as there's no perfect rose."
This article was provided to the TVRS as a courtesy by the American Rose Society.