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How to Prepare Roses for Cold Minnesota Weather

Here at Gertens, we have a few tried and true tips for how to prepare roses for cold Minnesota weather. Read on to learn about our "Minnesota Tip” and other proven methods of protecting roses against early freezes in the fall, the bitter cold of winter, and the dangers of thaw-freeze cycles in the spring.

Winter

Protecting your Roses is neccesary in winter in Minnesota.

Winter protection actually starts with work you do during the summer to bring your roses into the fall season in the best of health. The last of the summer steps would be an application (around August 15th) of a rose food rich in potash and phosphorus, but free of nitrogen. A good food would be 0-20-20. Here are the steps to follow to protect your roses during the winter and early spring. A good starting date would be about October 20th, and certainly before the temperature threatens to reach 20 degrees Fahrenheit. A drop below that temperature would kill or severely damage unprotected roses.

  1. Water generously to keep the soil in good, moist condition.
  2. Give your plants a good dormant spray. Some of the popular sprays for this purpose are Phaltan, Mildew King, and liquid lime-sulphur.
  3. Tie the canes of the bushes together to make them easier to handle.
  4. PRUNING: Most growers avoid fall pruning, because the open wounds on the canes may not heal properly. Cold weather may prevent the formation of a protective callus.
  5. Dig a hole, starting away from and working toward the base of the bush. Dig the trench as long as the bush is high. Dig it wide enough and deep enough to accommodate the bush or bushes. (You can put more than one bush in a good-sized trench.) Pull the soil away from the shank (the root stock just below the bud union or graft – see figure below). Dig carefully so as not to damage the bush or its roots. Use a spade or shovel for the trench. Use a spading fork in loosening the soil around the roots.
  6. When the trench is ready and the roots of the bush are loosened, use a spading fork to push the bush into the trench. (See figure below) Use the spading fork (or wire loops or weights) to hold the bush down while you cover it with 2 or 3 inches of soil. If the soil you removed in digging the trenches is not enough, add soil from your annual garden or elsewhere. REMEMBER: In the tipping method, only the roots bend. Pull the soil away from the shank, and it will be easy for the roots to bend.
  7. Cover the soil with about 1 to 2 feet of loose leaves or other covering such as marsh hay.
  8. Place rodent repellent such as Repels All among the leaves to discourage the visits of small (but destructive) field animals.
  9. Water the leaves well. The water cuts down on the danger of fire and also formed ice crystals to help the plants stay in a dormant state. Use fencing (chicken wire is good) around the rose bed (or lay it on top of the leaves) to keep leaves from blowing in a strong wind.

Spring

Start spring care around April 1.
  1. Remove the leaves in easy stages as leaves thaw.
  2. Remove soil gradually as the ice crystals thaw on remaining leaves and the soil thaws.
  3. On or around April 15, raise the plants to an upright position, very gently.
  4. Water the plants and keep sprinkler going on them. The water will keep the canes wet and protect them against drying winds.
  5. Spray with a good all-purpose fungicide and insecticide like Infuse and insecticide such as Eight.
  6. Work into soil generous amounts of organic matter during the latter part of April.
Note: For each of the methods listed below, follow steps 1, 2, 3, and 8 described in the preceding section. Do no pruning in the fall except when specified.

Variation of the "Minnesota Tip"

  1. Using a spading fork, gently loosen the soil all around the base of the bush. Then still using the spading fork, push the bush gently over onto the ground. The plant should bend at the roots (below the shank); the soil should be very loose around the shank. Use wire loops or stakes to hold it down.
  2. Cover rose bushes with 2-3 inches of soil and about 1 to 2 feet of leaves or marsh hay, holding in place by fencing around entire rose bed. Water the leaves well. Another variation would be to cover with just 2 feet of leaves or hay, using no soil.
  3. In the spring follow the same procedure as for the Minnesota Tip.

Bend, Hill and Cover

  1. Bend the bushes over very gently and carefully in an arch; pin or tie down with wire loops or stakes. Great care must be taken to avoid breaking canes off at the roots. Don’t try to bend short bushes. Mound up base of bush with soil (about 9-12 inches).
  2. Cover the bushes with about 2 feet of leaves or marsh hay, held in place by fencing or chicken wire around the entire bed. Be sure the leaf cover extends out at least 1 to 2 feet from the center of the bushes. Water leaves well.
  3. Follow the same procedure in the spring as recommended for Minnesota Tip

Hill and Cover

  1. Mound up the base of each bush with soil – about 9-12 inches. A wire cylinder may be used to hold the soil in place. Very tall canes, which would whip too much in strong winds, may be cut back and the cane ends sealed.
  2. Cover entire bed with about 2 feet of leaves or hay, held in place by a fencing. Water.
  3. In the spring, gradually remove the leaf cover, starting around April 1. Then gently wash the soil off the bushes in stages, beginning around April 10-15. If additional soil was brought in to mound in the fall, be sure to remove the excess soil.

Polystyrene Cones

  1. Prune back the bush to accommodate the cone. Then place the cone over the bush and tightly seal the bottom of the cone with soil. Weight the base of the cone down with more soil, gravel, stone or some other weight material.
  2. The cones with detachable tops (for ventilation) are best; with these on warm days in late winter, the rose bushes can and should be given some air. The cones get like a miniature greenhouse with the warmth of the early spring sun. Mold can be a very serious, severe problem then; if unchecked it can cause death of the canes.
  3. In the early spring, remove the cones when temperature gets above freezing. Keep them handy to put back as necessary, for the plants will be very tender and sensitive to sun and drying winds in addition to the cold.

Winter protection is essential for Minnesota.

It must serve two functions:
  1. To keep temperature high enough to prevent winterkill.
  2. To keep temperature low enough to keep the roses dormant and prevent active growth.
Covering also serves to keep the sun and wind off the bushes. The sun and wind during the colder months can dry and wither the canes, a common cause of winter damage.