April Advice By, Barbara Kemp Master Rosarian
The March blizzard (the fourth largest snowstorm on record in Denver) still has lingering patches of snow in my yard as we continue to get smaller snowstorms going into April. These storms brought the much-needed moisture to our roses and to the many drought areas of Colorado. Will the snowy weather pattern continue into April? This is Colorado and anything can happen! During April, our roses require attention!
- Clean Rose Beds: This is an ongoing task removing winter leaves and debris; do not compost, dispose into the trash as there could be diseased leaves.
- Bare Root Planting: There is still time to plant bare root roses through mid-April. When plants arrive, they can be planted within a couple of days, depending on the weather. The rose needs to be hydrated by placing the roots or complete rose in a bucket of water, using fresh water each day. Go ahead and dig your hole (18 to 24 inches by 14 to 18 inches deep). Place the rose in the hole to check for ample space for the root system and to ensure that the graft (bud union) of the rose is three to four inches below the soil level or that own root roses are planted with the branching point one or two inches below the soil level. How do you determine the soil level? Place the handle of a shovel across the top of the hole, and when the rose is placed in the hole, you then can visually identify the depths needed for a grafted or own root rose. For more details on planting roses, refer to Growing Roses in Colorado.
- Transplant Roses: This is a great time to transplant roses using the similar or same planting guidelines as bare root roses. (If soil falls away from root ball, plant as a bare root rose.) After planting, protect the transplanted rose by mounding soil around canes, using burlap strips to keep soil in place and cover with burlap, as needed, until new growth becomes visible.
Other Items: Pruning shears need to have sharp blades. Long-handled loppers have more leverage for cutting larger, thicker canes, so sharpen those blades too. A small pruning saw is optional, but it is great to remove larger dead wood at the base of the rose.
A good pair of leather gloves protects from thorns and scratches. Use waterproof glue or colored fingernail polish to seal canes after pruning. Waterproof, Titebond III ultimate wood glue is a good product to use for sealing canes.
Pruning: We recommend pruning the last week of April into midMay. If you begin pruning before the last hard frost, there is always a risk of damage to the rose and additional pruning would be needed that could delay the first “bloom” of the season.
Pruning rejuvenates the health of roses each season by taking out the dead, damaged canes and, of course, removing diseased canes (known among rose growers as the “three Ds”). Sometimes hard pruning is necessary to reach healthy tissue where the pith (the central portion of the cane) is healthy, white or cream colored.
Older mature rose bushes may have older canes that need to be pruned out to allow light and air circulation. A small pruning saw is very helpful for removing these thick canes. If the bush is extremely large and you cannot prune out all dead wood in one season, it can be completed the following year.
Roses planted one year or less will have minimal pruning. They need to grow and gain strength, so just remove diseased canes and those canes in the center that cross or rub on other canes. This also will open the center and allow good air circulation.
Again, all leaf and pruning debris should be removed from the garden and discarded. It should not be composted or used as mulch as there is always the potential to carry disease to healthy roses.