The following is a general description of rose care activities to consider in the winter. If you run into unusual problems, don't hesitate to contact a Consulting Rosarian. If there are questions not answered in this text, we strongly recommend contacting an ARS Consulting Rosarian.  For more in-depth information on plant problems and the details on procedures for optimizing plant performance in Metropolitan Washington DC, it is highly recommended that the viewer subscribe to our monthly newsletter, The Capital Rose, jointly produced by the Potomac Rose Society and The Arlington Rose Foundation.  

To obtain strong, healthy bushes and beautiful blooms, the rose gardener is busy in spring. Spring rose care includes: a) Pruning; b) Fertilization; c) Disease and Pest Control.

PRUNING: As this is written in late February, this year's winter in metropolitan Washington DC saw no deep snowy blizzards. There were periods of ice, snow, and cold, followed by short bursts of warmer weather. Fortunately, most rosebushes went dormant and dropped their leaves.

A good rule of thumb is to hard prune your roses when the forsythia blooms, which tends to be about mid-March here. If one prunes sooner, new growth is encouraged and the bush is less protected, such that a surprise freeze can damage canes. If the canes were pruned early and are then afflicted with late freeze die-back, there is not much left after re-pruning to remove the die-back. On the other hand, if bushes are not yet pruned and are hit by a March freeze, the die-back would be at the ends of the cane, not the middle or base, and is easily removed during the first pruning.

For Hybrid Teas, Floribundas, repeat-blooming OGR's, and most Shrub roses, general advice is that if one wants a larger number of smaller blooms, such that the bush looks pretty in the garden, one prunes to about three to four feet. If one wants a smaller number of larger blooms, such as to enter at a rose show, then prune harder - down to about 18 inches to two feet.

Eliminate dead and spindly stems. If the bush has five to six large canes, cut the less vigorous ones back to the bud crown. Make your pruning cut just above a "good" bud.

If, after a cut is made, you notice that the cross section of the cane is discolored or has a "mushy" nature, cut lower. Continue cutting until you have a nice solid end surface with no discoloration. In some years, this may call for cutting down to several inches above the ground. To encourage good air circulation around the plant growth, the pruning cuts should be above outward facing budeyes.

Other types of roses are pruned a bit differently. With Miniature roses, one may either scale down the advice for Hybrid Teas to a smaller plant, removing twiggy growth, examining canes and branches individually, and cutting down to three or four main canes with sub-branching removed and discarded. Otherwise, one may prune the bush quickly, by running a hedge saw or large clippers over the top and sides.

For Continuous-Blooming Climbers, the main canes tend to be laid out horizontally or in an arching pattern to encourage vertical laterals to form at each budeye on the canes, where the laterals form stem for flowers. This approach yields a "wall of color." (If climber canes are left to grow vertically, blooms mostly will develop only on the tops of those very long canes.) After canes are laid out laterally, prune the vertical laterals hard, to encourage new growth and blooms.

For Once-Blooming OGR's, trim the bushes lightly to clean them up, but do not prune severely or you will have no blooms. (Once blooming antique roses should be pruned after they bloom - say, in late June or July.) Of course, dead wood or crossing branches should always be removed.

For all classes of roses, all pruning should be performed with sharp pruning shears. A rule I use to determine if my shears are sharp enough, is to try cutting a piece of paper. If it makes a clean cut, it's OK for the rose pruning. For pruning or any other cuts made during the growing season, it is a good idea seal the open cut to discourage the small carpenter bee from drilling down the center of the cane. Seal the cut by squirting a dab of Elmer's Glue or garden sealant on the end of the rose cane.

In addition, check back several weeks after the initial pruning to see how the plant is reacting to your pruning. If any canes die back, they should be removed.

FERTILIZATION: Most rose gardeners begin to fertilize after the rosebush has put out some green growth, which tends to be early to mid-April in metropolitan Washington DC. Fertilizers include inorganics, liquid inorganics, organic meal mixes, and liquid organics.

If you employ an inorganic fertilizer like 10-10-10, apply it at about one cup per large bush (one half cup for minis), scratched into the top three inches of soil, in early April, early May, mid-June, and early August. After applying, water in the fertilizer.

Otherwise, if you employ a time-released inorganic fertilizer like Osmocote, apply it according to the directions in April and you do not need to fertilize again. For example, at Bon Air Memorial Rose Garden in Arlington VA, with about 3,000 rosebushes, the rose gardeners apply Osmocote once in the spring, and the Hybrid Teas grow to be six to eight feet tall. (Bon Air Memorial Rose Garden is located at 850 North Lexington St., at the corner of Wilson Blvd.; Arlington, VA; 22205.) To minimize gardening time, I myself use Osmocote. One of my friends also uses it in the spring, but, as a booster to her roses, she adds an organic fertilizer, Mills Magic Mix, at that time and once again in early August.

Liquid inorganics like Miracle Grow may be applied up to about every two weeks if they are the only fertilizer used. They are applied with a hose end sprayer or possibly by a watering can for a small garden with two to three rose bushes. One should water the bushes first and be careful about salts. However, some rose gardeners apply liquid inorganics only twice or three times per year as a boost, about two to three weeks before peak bloom.

For a boost, avid rose gardeners also may apply an organic fertilizer. One of my friends mixes his own organic fertilizer, using equal parts alfalfa meal, blood meal, cottonseed meal, and fish meal. Otherwise, one may buy a commercial product like Mills Magic Mix. One may alternate with a liquid organic like "Alfalfa Tea."

DISEASE AND PEST CONTROL: To prevent fungus disease on roses, the prudent rose gardener will water in the morning or early afternoon, so leaves can dry off by evening, and he or she will trim branches to encourage good air flow.

However, in hot, humid Washington DC, to prevent fungus diseases like blackspot, powdery mildew, and botrytis, the gardener generally needs to implement a chemical spray program. For example, with blackspot, once a leaf is infected by the blackspot fungi, there is no cure. So the strategy is to protect the new leaves. And it should be noted that each of the spots, a half inch or so in diameter, can contain between 500 and 1,000 blackspot spores, each of which can be transported to a fresh new leaf, where a new colony of 500 to 1,000 spores are formed, each of which can initiate a new colony, etc.

Fungicides fall under two main classifications. The Surface or Contact Protectants stay on the surface of the plant material, unless washed off by rainfall. They also have the capability to attack the blackspot fungus in a large number of ways. This is referred to as a multi-site characteristic. Surface fungicides include Daconil (active ingredient chlorothalonil), Bordeaux Mixture (copper sulfate and hydrated lime), and Dithane M-45 (mancozeb).

The Systemic Fungicides, by contrast, are absorbed into the plant tissue so they are not affected by subsequent rainfall. But the systemics are only single site fungicides, attacking only one biochemical function of the fungus and probably in less than 100 percent of the cells. Frequent use of one single-site fungicide could result in the development of a strain of blackspot resistant to that fungicide. Systemic fungicides include Funginex (active ingredient triforine), Banner Maxx (active ingredient propiconazole), Cleary's 3336 (active ingredient thiophanane-methyl), and Immunox (active ingredient myclobutanil). Compass (active ingredient trifloxystrobin) is a mesosystemic.

To prevent fungus resistance, it is recommended that one alternate systemics. Alternate spraying a systemic one week with a contact spray the next week or two - such as Funginex one week and Daconil next. Or alternate systemics that have different active ingredients - like Funginex with Immunox or Banner Maxx with Compass or some other combination.

The other fungus problems found in metropolitan Washington DC include white powdery mildew, found after a period of cool nights and warm days, and botrytis, which affects the flower bloom, ranging from pink spots to a bigger problem, where the bloom balls up and does not open. Most fungicides that prevent blackspot also prevent powdery mildew and botrytis. For a mild case of botrytis, peel off the outer layer of petals from a bloom by hand. For severe powdery mildew, spray systemic fungicide Rubigan (active ingredient fenarimol) or E-Rase (jojoba oil).

Finally, it might be noted that downy mildew is more common out west and is rare here. But the past two years' cool, wet weather caused a few local rosarians to find outbreaks and they sprayed with chemicals like Aliette (active ingredient fosetyl Al). Downy mildew is a serious, contagious problem that defoliates and kills rosebushes, so one should immediately contact a CR for customized, intensive help.

Regarding insects, in mid to late spring we begin to note insects in the rose garden. Many are beneficial; a few are destructive. The approaches for insect control vary with rosarians, depending on the level of plant damage they consider tolerable. In most cases, the beneficial insects (such as the syrphid fly larvae, the paratisizing wasp, lace wing larvae, and the lady bug/beetle and its larvae) will control the damage by destructive insects.

Spraying a hard stream of water by a garden hose under minis and low rose bushes will control spider mites. (Spider mites move in from grass and can defoliate a rose bush, so if you suffer an outbreak, spray every two days the first week, then twice per week, and then less often.) To control thrips in cut roses that you bring into the house, you can breathe hard or "huff" onto the blooms, and thrips will think they are about to be eaten and will fly away. Rosarians who want stricter insect pest control might spray with the systemic insecticide Merit (with active ingredient imidacloprid) or another insecticide. (Probably, Japanese beetles will not show up till mid-June, after the first flush, so we will worry about them in the summer advice letter.)

If you have any questions about the spring care, please contact a Consulting Rosarian. (Click on "Consulting Rosarians" on this web-site, for a list with phone numbers.) The Consulting Rosarians in Washington, northern Virginia and suburban Maryland know the local weather and soil conditions and they will be glad to help you.

In addition, the reader is encouraged to look at The Capital Rose, the award-winning membership newsletter published jointly by the Potomac Rose Society and The Arlington Rose Foundation. It describes current rose care problems and how to solve them, among other topics. Further information on membership in the Potomac Rose Society can also be found on this website.

Finally, should there be any questions on the past year's performance or questions in planning for next year, I recommend contacting a Consulting Rosarian.  (Click on "Consulting Rosarians" on this web-site, for a list with phone numbers.)  The consulting Rosarians are faced with such a wide variety of problems that they may be very familiar with your particular problem.

I would be happy to receive any question on particular cases.  The email is aldeco@verizon.net

"Bob"

(Robert Alde - Consulting Rosarian - American Rose Society)