Cultivating Roses: Planting, Pruning, and Winter Care
Cultivating roses is a gratifying endeavor that comes with its own set of challenges. On one hand, there are the vivid, flourishing shrubs that enhance any landscape; on the other, there are ongoing battles against lingering diseases and pest damage. Additionally, the labor-intensive efforts required to safeguard these delicate plants from freezing temperatures can be physically demanding. The varied requirements for planting, pruning, and winterizing roses necessitate adapting techniques based on the specific type of rose and the local climate conditions.
Planting: Grafted Roses and the Bud Union Controversy
When introducing a new rose to your garden, the initial planting and winter preparation depend largely on whether you are dealing with an own-root rose or a grafted rose. Own-root roses grow on their inherent root systems, whereas grafted roses consist of a particular cultivar attached to a more resilient rootstock. The swollen area where this graft occurs is called the bud union.
There is a significant debate among experts regarding how deep to plant the bud union. Renowned rosarians have differing opinions on this issue, each with their own rationale. Some advocate for burying the bud union below the soil level at planting time, reasoning that it serves as a natural insulator, eliminating the need for winter protection later on. Others argue against this practice, preferring to keep the bud union above the soil line, which requires more effort in the fall but offers lower maintenance during the winter. If you prefer a less labor-intensive fall, consider burying the bud union, but remember that this approach is highly controversial among top growers.
Late Summer and Fall: Signaling Dormancy
Preparing roses for winter is a biological process that begins well before the onset of freezing temperatures. Understanding these biological processes explains why some methods fail and others succeed. Rather than abruptly forcing a plant to endure cold conditions, gardeners must allow the plant to naturally transition into dormancy.
You should cease fertilizing roses by August and stop deadheading by Labor Day. By allowing the plant to set hips (the seed pods of the rose), you signal the rose to enter dormancy before the freeze sets in. Autumn is also the time to tackle the less appealing aspects of rose maintenance: disease control and sanitation. In harsh climates (zones 3-4), it is crucial to remove blackspot debris before winter to prevent carry-over disease.
Once the cleanup is complete, a common misconception is that roses should be heavily pruned in the fall. However, you should wait for two hard freezes before taking the garden to bed.
The Pruning Debate: Spring vs. Fall
When it comes to pruning, experienced gardeners have differing opinions on the timing. These disagreements are closely tied to climate conditions and the potential risks to the plant.
One school of thought suggests waiting until late winter or early spring to prune. The rationale is that pruning stimulates new growth, which would be vulnerable to frost damage if done too early.
In contrast, others argue for pruning by a third in the fall to prevent a phenomenon called "wind-rock." Wind-rock occurs when harsh winter winds cause tall, unpruned canes to whip back and forth, loosening the roots. This method is often preferred by Southern gardeners or those in highly windy areas to secure the root system.
Pruning Techniques and Rose Classes
The techniques used for pruning vary depending on the specific class of rose. Repeat-blooming roses, such as floribundas and hybrid teas, require a different approach from old-fashioned, once-blooming climbers. Old-fashioned climbers bloom on old wood, and heavy pruning before they bloom would remove all the flowers for the next season.
When pruning, look for the signs of a healthy cane. A solid, creamy-colored interior indicates that you have cut past any borer damage. If the center of the cane does not exhibit this color, the cane has been compromised by insect damage, and you must cut further down the stem.
The severity of the pruning and the number of canes left on the plant also vary by region. In cold climates, rosarians might advise leaving only three canes per hybrid tea rose. In warmer zones, up to nine canes might be left. If you prefer a full, sprawling shrub in a mild climate, leave more canes intact. In harsh climates, pruning down to just three canes can help the plant focus its energy on a few strong blooms.
Related on Landscaping Bible: Ground Covers for Shade: What Actually Thrives Under Trees, Prepare Your Garden for Winter, How to Create a Native Pollinator Garden in Fall, Overseeding and Aeration in October for a Thicker Spring Lawn.
Winter Care: Wraps and Unearthing
Once pruning and garden cleanup are complete, the final winterization can begin. The methods used can range from straightforward to highly complex, depending on the type of rose.
For container roses, specialized wrapping is needed to insulate their roots, as they do not have the same level of protection from the surrounding soil. For standard tree roses in harsh winter climates, the winterizing process can be labor-intensive. One method involves unearthing half of the rootball, laying the plant flat on the ground, and covering it for insulation. While this method is physically demanding and time-consuming, it uses the earth to protect the vulnerable trunk and graft union from severe winter temperatures.
Cultivating roses involves navigating a variety of horticultural techniques, biological realities, and contentious practices. By understanding the specific needs of your rose classes, recognizing the importance of biological signaling, and considering your local climate, you can make informed choices to keep your plants healthy through winter and thriving into the next year.
