Winterize Hybrid Roses

Abrupt temperature changes, especially from very mild to very cold, can cause severe damage to roses. The amount and type of protection given depends on the type of rose and its location. In our climate, dieback of canes is common during many winters. A little dieback is of no great concern. However, severe kill-back and damage to the bud union near the base of the plant can seriously weaken or even kill plants.

Because vigorous start in spring, they can developed into some very tall plants. Start winter preparation by removing excessive top growth. Cut back tall canes to about half their total length. At the same time, remove thin or brushy growth. Tall or brushy growth catches strong winter winds, causing plants to whip back and forth. This movement can cause the root system to be torn loose and weakened. The base of the plant is then more exposed to weather conditions as the plant moves and soil is pushed away to from an open hole around the base. This exposed stem is easily damaged. It is especially serious, since the union of the rootstock and the hybrid variety is open to the elements.

In addition to cutting back the tops, a mulch over the base of the plant is the best method for protecting it. A mulch insulates the base of the plant against rapid temperature changes and also against drying. Its greatest benefit is the protection of the bud union where the plant was grafted. A mound of some material placed over the base of each plant is one of the most dependable methods for protecting roses. Soil is very effective, inexpensive and easily available. Do not dig up soil for mounding from between plants, particularly if they are very close together.

It is best to bring soil from another area of the garden. Aged sawdust, bark, chips, straw, ground corncobs, or other such materials may also be used to form a mound. The mound should be made about 12 inches high and about 18 inches broad at the base. As many of these materials settle, they may drop a few inches. But if any settle to less than 8 inches in height, more should be added. The mound should be made about 12 inches high and about 18 inches broad at the base. As many of these materials settle, they may drop a few inches. But if any settle to less than 8 inches in height, more should be added.

Before making a mound on a plant, fall cleanup is important. Remove all plant debris and diseased parts. Black spot was a serious problem of roses this year. Collect any fallen leaves that may still be around the base of the plants. Infected leaves that remain in the garden are a source of infection for next season. If no disease was present, this step is less important. Mounding should be done now with no danger of other problems. Mounds made too early sometimes keep stems too warm and moist. This can allow infection by stem canker disease if any are present. Even though this is not a serious problem, spraying lower stems and the base of the plant with a fungicide before mounding is a good precaution. Fungicides normally used for black spot control are useful for this purpose.

Rose plants close to buildings, fences or other structures, that give wind protection, particularly from the north or northwest, often survive with less winter protection than those in exposed locations. In northern areas or where plants are exposed, windbreak protection added over the mound is necessary. Branches of evergreens, straw, or other loose materials among the canes help reduce die-back. Wooden containers, baskets, or wire cylinders around the plants and filled loosely with leaves can be helpful. Even tying branches together, and wrapping the plant with a pliable material used for home insulation has been successful for some home gardeners.

http://en.wikipedia.org/wiki/Hybrid_Rose