Fertilizing, Pruning and Winterizing Roses
[B]Fertilizing, Pruning and Winterizing Roses[/B]
HYG-1205-96
Cindy Welyczkowsky
*Jane Martin
Throughout history roses have captivated the hearts and minds of gardeners and non-gardeners alike, inspiring the creation of numerous poems, legends, and books on their uses and care. They are one of the most popular garden flowers grown on the face of the earth as evidenced by the several garden clubs, societies, organizations, and businesses devoted to them. There are countless species and cultivars available in a wide range of colors and forms, with new cultivars being introduced each year to improve on the previous year's selections.
With the abundance of information available on roses and rose care, there is still some mystery about their proper care and maintenance. For every different type of rose available, there is probably a gardener with a different approach to caring for roses. It is as much of an art as it is a science to growing beautiful roses, but the following information will give you some important basics to help demystify the process. This fact sheet will discuss fertilizing, pruning and winterizing roses.
[B]Fertilizing[/B]
Because roses are heavy feeders, a routine fertilization program is important for plant health and vigor. To provide the proper nutrients for your roses in the amounts needed for optimum growth, it is important to first test your soil to determine its pH, texture (i.e., clay loam, sandy loam), and existing mineral nutrient content before adding fertilizer. A soil test kit can be obtained by calling your county Extension office. The amount of fertilizer and types of amendments you apply will be determined by the results of the soil test. Following the recommendations will assure you will neither over nor under fertilize your roses. A soil test should be done prior to planting and every two to three years thereafter.
Roses grow best in the pH range of 5.5 to 7.0. Soils testing below 5.5 will need an amendment of dolomitic lime, 7 to 8 pounds per 100 square feet, to raise the pH into the desired range. Powdered sulfur can be used to lower the pH. For soils with a pH between 7 and 7.5, add one pound of sulfur per 100 square feet; for a pH between 8 and 8.5, add two pounds of sulfur per 100 square feet; and for soil with a pH over 8.5, add three pounds of sulfur per 100 square feet. Ohio soils are often deficient in iron when the pH is above 6.5. Iron sulfate can be used instead of powdered sulfur to decrease the pH and provide the needed nutrient. Also, chelated iron products are available for foliar feeding or soil application.
Soil texture, which is the relative percentage of sand, silt and clay composing soil, will influence the amount and frequency of fertilizer application. Sandy loams, for instance, will require more frequent applications because they drain rapidly, leaching essential nutrients. They contain little clay (and possibly organic matter) that would normally hold nutrients.
It is always a good idea to amend your soil with organic matter, such as humus, peat moss, manure or composted sewage sludge for an added source of slow release nutrients. The addition of organic matter will also improve the soil's drainage and nutrient holding capacity. It is recommended that two to four inches of organic matter be added and worked into new beds to a depth of 12 inches. Many gardeners find the combination of organic materials and a fast release, complete, inorganic fertilizer, such as a 5-10-5, 10-10-10 or 12-12-12, works best to produce beautiful roses.
In general, roses do well with an application of 3 pounds of actual nitrogen per 1000 square feet (or 0.3 pounds of actual nitrogen per 100 square feet), divided into three applications per year. To calculate how much fertilizer to apply depending on the formulation, use the following example.
[B]Example:[/B]
Using 5-10-5 fertilizer at the rate of 3 pounds actual nitrogen/1000 square feet.
3.0 pounds actual nitrogen divided by 0.05 (5% nitrogen in 5-10-5) = 60.60 pounds divided by 10 (1000 square feet to 100 square feet) = 6.0 pounds of 5-10-5 fertilizer per 100 square feet.
Using the above example, a total of 6 pounds of 5-10-5 fertilizer will be applied to a 100-square-foot rose bed per year. The 6 pounds will be divided into three applications (2 pounds each); the first in mid to late May (for spring planted roses the fertilizer should be applied after new green vegetative growth begins), the second in mid-July, and the third in the autumn after a killing frost, or very early in the spring before new growth begins.
[B]Pruning[/B]
An area of concern for many gardeners new to growing roses is pruning. Why do you have to prune roses? What kind of tools do you need? When is the best time to prune? How do you prune? Does it matter what type of rose it is?
Basically, pruning is done to improve the appearance of the plant, to remove dead or diseased wood, to let in sunlight and air to the center of the plant and to control the quantity and quality of the flowers produced. Deadheading, or the removal of spent blooms during the season, encourages more blooms (on continuous blooming varieties), improves the appearance of the plant, and removes potential harboring sites for disease organisms.
Prune rose bushes to a uniform height, between 12 and 24 inches; remove suckers below the soil line.
The tools essential for pruning roses are pruning shears, long handled lopping shears and a fine toothed curved saw. All should be sharp to produce clean cuts and to avoid tearing or crushing the stems. When buying pruning shears, look for the hook and blade type, which have two cutting edges like a pair of scissors. The anvil type pruners, with one cutting edge, will crush the stem. Long handled lopping shears are best used on thick canes or ones difficult to reach with pruning shears. A fine toothed curved saw is used for larger climbing roses. You might also want to invest in a pair of heavy duty gloves to protect your hands from sharp thorns.
In general, roses should be pruned just before growth begins in March or early April. The exceptions are old (heirloom) roses and some climbers that produce blooms on the previous year's wood. They should be pruned after they bloom.
[B]Pruning Bush Roses[/B]
Following a logical sequence of steps while pruning will help make the job seem less complicated. The first step is to remove any dead, diseased or damaged wood. Cut the stems one inch below darkened areas, making sure you are cutting back to green wood. Make the cut at a 45 degree angle about 1/4 inch above an outward facing bud. Inspect the pith (center of the stem). It should be white. If tan colored, continue pruning sections of the stem until the pith appears white.
The second step is to remove branches that grow toward the center of the plant. This opens up the plant for better air circulation and allows sunlight to penetrate the inner portion of the plant.
The third step is to locate crossing branches and remove the weakest one. Crossing branches may rub against each other, causing abrasions that may serve as openings for disease organisms to enter the plant. Remove sucker growth, which is growth coming from below the bud union. Sucker growth is from the root stock and is a different rose variety; if not removed, sucker growth will crowd out the desired variety.
Finally, prune to shape the plant. Hybrid teas, grandifloras and floribundas can be pruned 12 to 24 inches in height, leaving up to 9 to 12 large (1/2 inch diameter), healthy canes. Old, shrub and species roses should be pruned lightly, removing no more than 1/3 of the growth. Miniature roses need only minimal pruning.
Many rosarians add one extra step to their pruning routine. After pruning, a water soluble, white glue (i.e., Elmer's) can be applied to the cut surfaces of the stems to prevent rose cane borers from entering.
[B]Pruning Rambling and Climbing Roses[/B]
The procedures for pruning Rambling and Climbing roses will vary depending on the type of rose it is. A pruning basic that remains constant, though, is removing dead, diseased or damaged wood whenever noticed. This improves the appearance of the rose and removes places for disease organisms or insects to overwinter.
The characteristic that distinguishes a Rambling and a Climbing rose is their pattern of flowering. The Climbing rose blooms continuously throughout the summer, while the Rambling rose blooms once. The Rambling roses can be subdivided into three groups, all of which are pruned differently.
It is important to note that the shoots of all Ramblers and Climbers should be tied to a support in a near horizontal position. These shoots will produce flowering laterals along their length and provide a generous display of flowers. Vertical shoots will tend to produce flowers only at their tips.
[B]Rambling Rose: Group 1[/B]
Ramblers in the first group are derived from Rosa wichuraiana, including the cultivars 'American Pillar,' 'Dorothy Perkins,' and 'Excelsa.' They flower on one year old shoots produced from the base of the plant. When planting new bare root plants, prune the canes to 9 to 15 inches. Train the vigorous new growth horizontally on a support. There will be no flowers the first season, but profuse flowering the next. Strong young basal shoots will develop, too. In late summer or early autumn cut the stems that flowered at their base and tie the new growth horizontally. A few old canes can be retained, if pruning all would leave the plant looking too sparse.
[B]Rambling Rose: Group 2[/B]
Group 2 differs from Group 1 only in the position of the new canes. The new canes for Group 2 grow half way up the old canes, not at ground level. Like Group 1, flowers appear on one year old wood. The plant is pruned after flowering by removing old wood up to the new growth then securing the new growth horizontally to the support. Examples of cultivars in Group 2 are 'Alberic Barbier,' 'Albertine,' 'New Dawn,' 'Paul's Scarlet Climber' and 'Veilchenblau.'
[B]Rambling Rose: Group 3[/B]
Included in this group are roses that are extremely vigorous, capable of growing 20 feet in one season. Examples are Rosa filipes 'Kiftsgate,' 'Francis E. Lester,' 'Wedding Day' and 'Paul's Himalayan Musk.' These roses are best used as a ground cover or to grow up into trees. Very little pruning is necessary, except when a plant begins to overwhelm a tree. Pruning can be done to reduce the size of the canes or whole branches can be removed at the base.
[B]Climbing Roses[/B]
Climbing roses bloom continuously on the current season's growth. They are moderately vigorous and their flexuous stems lend themselves to supports, such as, fences, pergolas, arbors, and walls. Examples are 'Handel,' 'Iceberg,' 'Meg,' Rosa banksiae 'Lutea' and Rosa 'Mermaid.' When planting new bare root plants, trim the roots only, not the shoots. Tie the shoots to a support system to train. Early the following spring, while the plant is still dormant, shorten flowered laterals to four or five buds. If pruning an established climber, prune the flowered laterals in the spring, the same way you would a new plant. Remember to remove any dead or diseased wood or stems arising from below the bud union. For climbers that are several years old, some of the oldest wood can be removed at the base to encourage new growth.
[B]Deadheading Roses[/B]
Removal of spent blooms, called "deadheading," is an important summer maintenance practice for roses, especially the continuous blooming varieties. Removing the spent blooms conserves the energy the plant would normally use for seed production, encourages repeat flowering, and removes potential disease harboring sites. Spent flowers may not be removed from species such as Rosa moyesii and R. rugosa because their large colored hips add another ornamental feature to the plant in the autumn.
To deadhead, remove the flower by cutting back, at a 45 degree angle, to the first outward facing bud in the axil of a leaf with five leaflets.
The continuous blooming climbing rose is deadheaded a little differently. Remove the spent blooms just above the foliage, making sure not to remove any of the foliage since new blooms will be produced from the leaves immediately below old flower clusters.
[B]Winter Protection[/B]
Winterizing roses is a very important maintenance practice to ensure vigorous growth from year to year. There are several things you can do to make sure your roses survive Ohio winters long before the cold winds blow. First, choose the most winter hardy roses available to plant in your rose bed. Next, make sure your roses are healthy and not under stress because they have a better chance of surviving winter than weak plants. Reduce stress on roses going into the dormant season by irrigating adequately in late autumn and discontinuing nitrogen application in late summer or early autumn.
For minimum winter protection, tie canes of bush roses together, then mound soil 8 to 10 inches high around canes.
Hybrid Teas, grandifloras and floribundas should be protected from winter damage after a killing frost but before the soil freezes. In Ohio, that would be late November or early December. Reduce breakage of tall canes by winter winds by cutting them back to 30 to 36 inches and tying tips together. Remove dead and fallen leaves around the plants. Hill soil over the center of the plants in broad rounded mounds at least 12 inches high and 12 inches wide. Cover the soil mounds with a mulch of leaves, straw, boughs, or some similiar material.
Another method includes using all mulch, such as, wood chips, sawdust, shredded hardwood, or pine bark, instead of soil, mounded to 15 to 18 inches. Some gardeners prefer to construct wire mesh cylinders to surround each plant, which they fill with mulch. Still others use rose cones, baskets with bottoms cut out or burlap to wrap the plants.
For maximum winter protection, cover the rose bush with a protective cylinder. Use straw, leaves or similar material to insulate the bush inside the cone. Puncture several one inch holes around the top of the cone for air circulation.
To winterize climbers, remove them from their support. Lay them on the ground and cover with 3 to 4 inches of soil. If this cannot be done, gather the tips of the stems together, tie them, and wrap in straw with a wrapping of burlap over that. The base of the climber should be covered with 10 inches of soil.
When severe winter weather conditions have subsided, which is typically mid-March or early April in Ohio, remove most of the mulch and soil from around the bases of plants. You may leave a 2-inch layer of mulch in the bed.
[B]References[/B]
Coombs, D., Blackburne-Maze, P., Cracknell, M., Bentley, R. (1994). The Complete Book of Pruning. Ward Lock. London, England.
Smith, Elton. (1988). The Culture and Care of Hardy Roses. The Ohio State University. Extension Bulletin 757. Agdex 276/21.
Taylor, Lee J. (1994). Roses for the Home. North Central Regional Extension Publications. Extension Publication No. 252.
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Clip art is copied from Roses for the Home, Publication No. 252.