SPRING PRUNING of established roses in the Midwest is always a gamble. If you prune too early, late spring frosts can kill all the canes. If you prune too late, some of the plants' strength will be lost in the growth of the top shoots (spinach).
You and you alone must be the judge of when to prune your roses. All roses must be pruned in the spring--don't think you can skip this job.
Here are some suggestions:
1. A green cane does not necessarily mean the cane is alive. Cane color can vary from green to red.
The only way to check on cane life is to lightly knick the bark to see if the green cambium layer of cells is alive. Start at the top of the cane and knick off chips of bark. Continue down the cane until you see the green cambium layer just beneath the bark layer.
Cut off cane portion which does not show the cambium coloration this pruning height may or may not be the proper spring pruning height -but it's a start in the right direction.
If the entire rose cane fails to show green beneath the bark down to the soil level-and your rose bush was properly planted with the graft union two inches below the soil line, don't despair as the wood beneath the soil is alive and will send up new shoots soon.
However, if the canes are "dead" down to an exposed graft union, the entire plant is worthless. Rather than wait for any possible future life (which usually shows up as nine leaved wild shoots from the under stock) dig up the plant and discard it.
2. Use a sharp pruning tool. If you know how to handle a knife, use it. Pruning shears are the next best tool and kitchen or sewing shears should be avoided.
3. Treat all pruning cuts with commercial plant wound paint. For temporary protection, use fingernail polish-any color. Wound treatment is necessary to prevent cane borer damage and possible disease attacks.
4. Prune canes to keep center of plant open to receive sunlight and air. Make slanting cuts directly above a cane node. Try to select a node which faces the "outside" of the plant.
5. Burn all cut off cane portions immediately do not use them as compost material.
6. Stagger pruning cuts at different heights.
7. To reduce the spread of "die-back" or canker, a dreaded fungus disease, disinfect pruning tool blades after each cut. Dip blades in strong solution of either potassium permanganate or 10 per cent hydrogen peroxide (both are available from your druggist).
For the most part, these suggested pruning heights for each type of rose are elastic. The natural growth of many rose varieties must be considered. Some varieties produce a "horizontal" or sprawling growth and these should be pruned back more severely than those types which normally send up extra-strong or lengthy canes.
Most of the pruning heights listed are higher than you may previously have followed. Higher pruning leaves more plant "food" in healthy canes to supply necessary energy for the first flush of spring growth.
Hybrid Teas, Floribundas,
Polyanthas and Grandifloras
Cut back extra-strong canes to a 12 to 18 inch height. Other canes ( as large in diameter as a lead pencil) should be cut back to within ten to 15 inches of the soil line.
It is seldom wise to leave more than six canes on any rose plant.
Remove completely any canes which rub each other by crossing.
All twiggy or weak growth should be cut back flush to a strong shoot.
Hybrid Perpetuals and Landscape Roses
Thin out old canes and keep only the largest. Prune these back to within two or three feet of the soil line.
(Read this section carefully as there are several different classifications, each with pertinent suggestions.)
1. Ramblers-Do not prune back any canes which are unbranched, smooth-barked or arise from the plant base-some of these shoots could arise from old canes very low on the plant. These canes just described will bear rose blossoms in 1958. If removed or even tipped, flower production will be reduced.
Dark-colored canes, usually wellbranched and constituting most of the plant mass, bloomed last summer and will never bear flowers again. All of these canes and branches should be removed completely.
Better plan to untie all canes from trellis or fence before pruning and I lay the canes on the ground. This action will make the pruning easier.
Once all the old wood is removed, tie up the remaining canes. Note the word "tie"-do not try to twist, twine or interlace rose canes into a trellis or fence partitions.
2. Climbing hybrid teas, floribundas and other everblooming pillar types Prune as described for bush types of these same rose varieties; but leave about one foot more of cane length than listed under previous suggestions.
Do remove all twiggy and excess growth.
Make pruning cut just above a bud.
To reduce height of fast growing rambling rose on an upright trellis, try looping and tyinge the flowering canes as shown.
When pruning is completed, before new growth has started, apply a dormant spray to canes and soil, to kill some of th eoverwintering spores of black spot.