By the time a rose is watered into the ground, about 90% of the factors that determine its care requirements will have been determined. We will cover these requirements:
!f the first four steps are done well, the rest of the steps may not need to be done at all. Of course, good cultural practices can vastly expand the number of roses that will flourish in any garden, so any person who is inclined to nurturing a garden and who covets the delicate colors and textures of the more difficult roses will thrill to succeed with cultivars that are known to be difficult, at least in part due to their very difficulty.
Do any of these steps is badly, and no amount of attention to the other steps will compensate. Do them well and the plant will likely thrive despite other steps.Slight or moderate amounts of the last four practices can improve the health and appearance of most roses.
In some cultivars the extra care will be necessary, but my own hope is that this site will help rose lovers minimize the time they spend on tasks they do not enjoy. Not many rose lovers get more joy from spraying their roses than from sitting in the garden and enjoying them.
Choose a Good Rose
The most important issue in caring for a rose is choosing one that will thrive where it is to be grown. Factors of temperature, light, humidity, water/rainfall, soil fertility, root competition, shade, and so on need to be considered.
Some cultivars will thrive in almost any cool continental environment. Most Albas and Rugosas, for instance, will produce delighful, dense shrubs even if grown in poor soil and given just three hours of direct sun per day. They are quite vigorous and range from being completely free of disease to thriving despite having some infestation.
Gallicas, Portlands, and Damasks will need more sunlight. And they prefer slightly more fertile soil. Disease resistance is more of a mixed bag. Of the Damask Ipsilante Austin says 'It is the most disease-resistant among old garden roses.' Several Portlands are almost as good. And most Gallicas are pretty good. But there are Gallicas and Portlands that are affected by fungal disease.
Centifolias and Mosses can be devastated by downy mildew. The worst offender in my own garden was Gloire des Moussouses. The diseased leaves are so infectious that neighboring cultivars that are normally disease-free can succumb.
Bourbons are said to have a weakness for blackspot, but several of the best are disease free. I find Zepherine Drouhin to be totally free of disease, and Great Western to be just about as good.
Hybrid Perpetuals are a mixed bag. The worst 90 + percent of them have been abandoned, so we would hope that most of the remainder will be relatively healthy. But they do feed heavily and will require regular fertilization. I've been impressed with Frau Karl Drushki (which should be catalogued as a hybrid tea). And while Mrs John Laing does get some fungal disease, its other merits are great.
Baronne Prevost, normally considered one of the best, has required extensive pampering in my own garden. I finally threw it out.
China roses when grown in zone 7 & 8 areas of less than 50% relative humidity are completely bulletprooof, but they will need regular feedings of organic fertilizer. They probably fare well in more humid climates. A gardener in Arkansas reports that in a garden where every other rose is almost dead from blackspot despite an aggressive spray program, only the Banksian roses are disease-free.
I have no direct experience with Tea roses. Their ancestors evolved in hot, humid climates, so I would expect that they should be disease resistant if given good feeding. And I expect the same from Noisettes for the same reason.
Most polyanthas and miniatures are of easy culture. And many of the old climbers and ramblers are as well. Yet one must be careful: Crimson Shower can suffer mightily from mildew and so can a number of direct descendents such as the popular Dorothy Perkins. Mildews of various kinds show up in a host of the most foliferous multiflora climbers. Using care, one can find disease-resistant cultivars - Newport Fairy instead of DP.
Shrub roses are the most profoundly mixed up of the bunch. As a group they are considerably more disease-resistant than any group but the Rugosas and Albas. But you can rarely get fragrance and remontance. For this you need to use Hybrid Musks.
English roses, especially some of the earlier ones can suffer from fungal affliction, but most of the ones on the market get by without much intervention.
Hybrid Teas draw from so many lines that it is difficult to say. There are healthy varieties, but even among AARS winners are roses like Apollo of 1973 which gets an abysmal ARS rating of 4.7. Probably ones with AARS awards and high ARS ratings are an excellent bet in places where they are cold hardy. Several suppliers are good at describing rose's weaknesses as well as strengths. Edmunds' is one, suggesting that Touch of Class 'separates the men from the boys' during fall when the rose will fall prey to mildew if not well protected.
Finding Good Cultivars
In my own garden I have found a strong corellation between ARS ratings and garden performance. Join the ARS and use their ratings booklet to make choices, especially if you are new to roses.
Breeders Buck, Pemberton, Lambert, Bentall, Svejda, W. Kordes, and Vibert have managed to produce roses with health characteristics well above average. Few of the roses released by these breeders will fail due to disease or lack of vigor.
Roses that have won the RHS AGM have proven garden-worthy. Those living north of the 35th parallel should consider these roses early on.
If you live in the US and must have hybrid teas, start looking at AARS winners and add highly rated ARS roses. There are some easy-care hybrid teas like Silver Jubilee and Marijke Koopman. Success with these may make you willing to exercise more effort in rose care.
Personal Easy-Care List
|Here is my short list of roses that I have found garden-worthy in New Jersey:
There are likely hundreds more. But there are also ten thousand or so that will probably not be worth the effort. Most of them, fortunately, will be difficult to obtain anyway.
Choosing a good Site
There are a number of issues to deal with in siting; the two really big ones over which you have control are sunlight and soil. Rule of thumb is six hours of direct, unfiltered sunlight per day. As for soil, a garden magazine recently interviewed a dozen prominent gardeners and asked them about their biggest mistakes. About three quarters of them listed trying to grow plants on poor, unammended soil!
I have killed more roses by siting them badly than the average gardener can in a year. My biggest siting problem is my desire to grow roses in the shade. But I also have terrible soil.
One fine spring afternoon I planted five Floribundas in an arc of sunlight that lay between two shadowy spaces. The path of the sun during the day lit most of the arc at least four hours. I finished the job feeling clever to have found a spot in a woodland to grow roses. But they all died. Some took two seasons to do so, but they died nonetheless. As the sun moved north during the summer, the illuminated arc moved south until by June the roses had no direct sun at all.
In another case, I read that the rose 'The Fairy' could withstand shade. So I planted it under some dense trees. I then forgot to water it in, or else never watered it again. The rose never got started.
One time I decided to plant six 'Old Blush' in an arc. I dug the first one into a nice hole two feet across and eighteen inches deep. In digging the next one in I encountered a limestone slab. I used a digging iron to excavate some of the slab, then planted the rose in a nice big hole. The dirt over the third site was thinner and I was a bit more tired, so the rose was planted a little closer to the limestone. And so it went until all six roses had been put into the ground.
A year later, the first rose I planted was four feet in each direction and was in flawless health. The next one was a little smaller. Each rose was smaller than the ones planted before until finally the last rose was about 2 ft high and showed slight sighns of chlorosis.
The main issues in siting roses are: sunlight, soil, water, and temperature. If these issues are addressed satisfactorily, any vigorous and disease resistant cultivar will thrive.
1) Choose a site with at least six hours of direct, unfiltered sunlight each day. If planting south of an overhang in spring, be sure that the sun doesn't move too far north to cast a shadow all day long on the plant at the height of the growing season in June.
2) If the rose is said to be 'shade tolerant' that means that four to six hours of direct, unfiltered sunlight should do. Some roses will survive on less, but few with thrive and bloom well. Unless you are willing to treat it as an experiment in pushing the envelope, do not plant a rose were it gets less than four hours of direct sunlight.
(I once grew Madame Plantier on the north side of a house where the rose got zero hours of sunlight per day. The rose did survive for two years but it grew leggy and it never bloomed)
3) Use fertile, neutral soil. Roses thrive on neutral or slightly acid soil. My experience suggests that soil that is too acidic will make them more prone to fungal diseases; soil too alkaline will cause chlorosis. Peat won't work. Nor will very sandy soil. Nor will soil laced with too much limestone or chalk. Very heavy clay soils will need plenty of organic material and some sand mixed in. Roses like fairly heavy soil with a good mix of clay, sand, and silt as well as lots of organic material.
4) Ammend poor soil. If you live where the soil is very high in peat, pure sand and gravel, or limestone, consider digging out a hole about three feet in diameter and two feet deep and planting the rose in that hole. Use imported 'rose soil' in the hole. Most people, however, can add things to improve the soil. Gypsum will loosen heavy clays; so will compost. Lime will help neutralize acid soils. Sandy soils can be made usable by adding lots of compost.
In ammending soil keep in mind that where there are abrupt changes in soil composition, most plants will not send new roots across the boundary, so if the soil in a hole is markedly different than the surrounding soil, create a zone in which the two are evenly mixed to help the roots make a transition into the surrounding soil.
It is a good idea to have your soil tested. It is not unusual for soil to be 'pretty good' in most aspects, but severly lacking in just one or two. Targeting the weak spots is the most effective path to good soil. In almost every location in the US the addition of organic matter (compost, etc) will be the most important step in improving soil fertility
5) Get ample water. If you live in a place that suffers frequent droughts, consider placing a rose where it will get extra water. I once planted a New Dawn rose at the outlet of a downspout in Texas, and the rose grew 24 ft in each direction in one season. Remember that climbers placed under the eaves of a house may not get as much rain as the rest of the environment, so they will frequently need extra water.
An inch of water per week is considered the minimal amount for plant maintenance. In unusually hot weather and growth periods a rose can benefit from twice this amount.
But roses do not like wet feet, so don't plant them in standing water or in boggy areas.
6) Use local micro-climate to advantage. In very hot, sunny places such as US zone 8 & 9 some roses will find the blistering heat of summer overwhelming. Rugosas and Albas, for instance will often fare better if given a few hours of shade in the mid afternoon. This means that they can be placed on the south-east side of trees, fences, and houses so that at about three or four o'clock they get shade.
Similarly, one can often grow climbing roses a hardiness zone beyond their hardiness rating by growing them against a warm south wall. Zone 6 occupants might try Don Juan or even Lady Hillingdon on a south wall.
7) Beware of hungry trees. Many trees and shrubs send out strong lateral roots extending far beyond their drip line. These roots effectively gobble up water and nutrients. If you encounter roots as you dig the rose's hole you can be sure that the roots will negatively affect the performance of the rose. If the rose is vigorous and non-remontant the affect may be minimal. But if you are trying to grow a marginal cultivar on poor soil, the tree can make the difference between success and failure.
How to Plant a Rose
The prime rule is to read and follow the instructions of the supplier who shipped the rose. Frequently suppliers will provide very good instructions. Many will be better than those that follow. And suppliers may require that you follow their planting instructions in order for any warranties to apply.
Roses arrive either in pots or as bare-root plants. If they are in pots, they can be placed outdoors and watered for some time before planting. Bare root roses arrive in boxes with bits of peat to keep them moist. It is best to soak each rose in a bucket of water for 2-24 hours befors planting.
Most of the business of planting the rose revolves around digging the hole. Farmers long ago coined the phrase "Dig a $10 hole for a $5 tree." Skimping on hole size can impare the development of a rose. One of the great advantages of budded roses over own-root roses is that they frequently have such large root systems that in turn require that a large hole must be dug.
1) Dig a hole. A rule of thumb that I use for most roses is to dig a hole whose diemeter about matches the diameter of the plant at the end of two years. I may give small roses a hole not much more than 18 inches across. Shrub roses get holes about three feet across. Climbers planted along a wall may get holes a little bigger than this. In any case, the holes should fully accommodate the roots.If the native soil is not too poor, then there is not much reason to dig a very deep hole; about one shovel's depth is good enough. Dig deeper, and the rose will sag too far below the surface after being planted.
If the soil is poor, and is being replaced with imported soil, then digging down eighteen inches or two feet may not be a bad idea, just be sure that the improved soil at the bottom of the hole is packed tightly so that the rose does not sink in when watered in.
2) Make a mound. Once you have a suitable hole, place a cone-shaped mound of soil in the center of the rose whose dimensions roughly match the cone defined by the roots. (If it is a potted plant, don't do this step.)
3) Place the rose into the hole. Try to make sure the roots are straight and evenly distributed around the hole. If it is a potted rose, check to make sure the roots aren't encircling the rose.
4) Fill halfway with earth. Add some slow-release organic fertilizer - perhaps a cup, and fill the hole with water. When the water has drained from the hole, fll in the hole with soil.
5) Pack the soil firmly. If your soil is so full of clay that this seems like you are just making bricks, then you probably should have added some compost to your soil.
6) Shape the surface. I like to make a cone-shaped indentation that catches water and sends it to the rose at the center of the hole. This is convenient for watering later on. If you water with a hose, and the rose is planted on a slope, some kind of dishing around the rose is imperative; otherwise all the water runs away from the rose.
7) Mulch. Place about 3 inches of mulch on the hole. This will limit evaporation, keep the soil cool, provide some organic matter to fuel life below ground, and limit weed growth.
8) Water In. Apply plenty of water to the rose. Water not only is required to cause the roots to become active, but it also aids in settling the soil into the hole, helping to fill large voids. This is essential to improve soil contact with roots. Water weekly the first year.
9) Water Regularly. For the first three or four months after a rose is transplanted, water every other day or so. Bare root roses are especially vulnerable because they have not formed feeder roots yet.
10) Get your roses in the ground early in the season when the soil is cool and moist. Ideally it will be before any roses on your property are setting leaf. Here in zone 6b I shoot for the last week of March or the first week of April at the latest. This year I was planting roses on March 15th. We've not had a hard frost since that date and the new roses are only a week or two behind the established roses in budding out. My success last year in planting the second week in April was nearly 100% compared to 50% in the fourth week in April and 10% for the second week in May.
How to Mulch a Rose
Mulch improves the quality of life of a rose in several ways:
A west-coast rose grower advocates piling mulch over most of the exposed canes of a new transplant, then removing it when the rose leafs out. This limits dessication, a major reason for failure in new transplants.
All sorts of materials are suitable for mulch. Some commonly used ones are pine needles, pine bark, wood chips, chopped roots, coconut hulls, cocoa hulls, and peanut hulls.
I can't think of why compost might not be used, or rotted leaves. Sometimes rocks and gravel are used as a mulch. This works to some extent, but it is less effective in most of the categories, and it does not help feed the soil.
Do not use grass clippings or unrotted leaves. They will decompose quickly and while doing so will eat up nitrogen and other nutrients.
Three inches is a good depth. Less than two and the beneficial effects dwindle rapidly. More than three and the plants start to treat it as a kind of topsoil - and mulch is not a very good topsoil. This is a bit less of a problem with deeply rooted roses than it is for other cultivars.
People in northern climates will sometimes pile mulch six inches or even a foot high to protect frost-tender roses. This is usually preceded by pruning the rose to a height that roughly matches the depth of mulch.
In the spring - as the tulips blossom - the mulch is pulled away from the rose. This solution works. There are more high-tech insulation blankets available for this purpose.
The head of a prominent garden in Quebec pulls the stems of roses down to the ground instead of pruning them. Then she protects them with a polyfoam blanket. Where rose stems are pliable enough to do this, it can work well also.
How to Water a Rose
Roses need water. Without it they will die. Roses, fortunately, are deep-rooted plants. Deep-rooted plants have the capacity to extract water from the sub-soil long after the surface has become dry. Also, many rose cultivars have fat trunks capable of storing some water. Finally, many hybrid teas and teas have relatively few leaves. All of these factors combine to make most rose cultivars fairly tolerant of moderate dry spells.
This said, a rose will be at its best if it is well watered. It will bloom well and it will be more resistant to disease. The organisms in the soil responsible for providing the rose with nutrients will thrive better with even moisture.
During the first year after transplant it is imperative that the roses receieve an inch of water each week, either from natural or artificial sources. This is doubly true of bareroot roses. Dessication almost certainly accounts for more than 90% of the loss of bare root roses.
During the first three months water at least three times per week. After the first three months, water at least once a week. Established roses will need watering less frequently, but still an inch of water per week is roughly what a rose will require.
Roses prone to fungal diseases will be particularly finicky about how and when they get water, but many old rose such as Albas, Gallicas, and Damasks may do quite well enough without any extra water after their first year.
The best method is underground or surface irrigation with a soaker hose. These hoses are about 50ft long and are constructed from recycled car tires. The rule of thumb is that roses need an inch of water per week. If you live where it rains 1 inch per week every week, then you will not ever have to water your roses. But this is true of almost nobody. So plan to water
In places where summers are cool, roses will have somewhat lower water requirements. And in the blazing heat of the Great Plains, two inches per week may be a better number, especially for large plants. In very hot places where roses go dormant during the summer, this also mitigates their water consumtion considerably.
How to Fertilize a Rose
We will artificially divide roses into two kinds; those that need feeding and those that don't. Of course roses fall into a wide range of categories, some do best with no feeding, some with modest feeding, and some require quite a bit of feeding. Some roses are completely happy on thin, sandy soil. Others really do better with a good bit of clay in the soil. All roses do better with organic material and healthy soil flora and fauna.
Before you pile a bunch of Miracle Grow onto your rose, remember that before the mid twentieth century all the nutrients that all the plants in the world got were derived by living organisms in the soil. These organisms produce as waste-products the things our plants live on. So when you pile a man-made material onto your soil you risk killing those beneficial bugs by smothering them in their own waste, which means that your plants are now totally dependent on regular deliveries of these fertilizers. Your plant becomes a fertilizer junkie and you have to supply a regular fix.
If, instead, you provide organic materials that can be digested by these same bacteria and fungi, your soil will become permanently more fertile. Man-made chemicals if used sparingly - especially in time-release form and with caution can improve garden results, but they can also set you on the road to chemical dependency.
Non-repeating roses such as Gallicas, Albas, and most Species roses will blossom but one time per year. In good soil they are capable of going years without feedings. Their performance can be enhanced by applying some slow-release fertilizer to the soil in early spring as the plant comes out of dormancy. By the time the fertilizer reaches the roots, the plant will be at a point where that feeding will really pay off.
Most roses will flower eight to twelve weeks from leafing out, then spend the rest of the season storing up energy for next season's display. A tiny bit of fertilizer after the blossoms go away probably won't hurt anything, but don't fertilize after midsummer.
Roses use up a lot of resources in making blossoms, so roses that repeat will tend to use up more food than those that do not. For this reason feeding of remontant roses: Hybrid Teas, Floribundas, Bourbons, Hybrid Perpetuals, and remontant Shrub Roses and Climbers is essential.
Apply a slow-release fertilizer in the spring as the roses start to leaf out. Then when the first flower opens add some more fertilizer. If you live in a hot part of the country and the rose stops producing blossoms over the summer, then it is a good idea not to keep dumping on fertilizer. But when the roses start blooming again in September you can add just a bit more.
If you live in zone 6 or cooler, it's probably not a good idea to fertilize roses after the first of September. The roses need to 'harden off' for the winter and fertilizer promotes soft new growth that is prone to freezing.
Last fall I added a lot of bone meal to my roses because the soil here is heavy in iron. I reasoned (though I should have tested it or called my local extension agent) that it could probably use more calcium and phosphorous. I imagined that this might help with the blackspot problem. We're not far into the season, but the new growth looks surprisingly strong and there is no trace of blackspot.
People who live in the southwest may need to add soil acidifier and supplemental iron from time to time to prevent the spiraling alkaline level from making iron unavalable and causing chlorosis. If one keeps the surface well mulched, the mulch will tend to moderate the pH of the soil, and additional chemicals may not be required as often.
Some people add greensand, which happens to be a rich source of a number of minerals. People on clay soils add gypsum as a soil ammendment to break up clay soil. It is a great source of calcium and it does not alter the pH of the soil as would limestone.
Choosing a Rose Fertilizer
People who raise exhibition roses may use foliar sprays that contain fertilizers. The assumption is that if you feed the leaves exactly what they need, it saves the plant the trouble of doing it for itself. The technique evidently works well enough to have a lot of followers; at least if used in moderation it does little harm.There are several things to look for in a fertilizer:
1) Choose one that is labled as being especially for roses. This will have the right balance of nitrogen, phosphorous, and potassium. Nitrogen stimulates top-growth. Phosphorous stimulates bloom, and potassium supports root development.
The lables state the amount of each in this order N-P-K (Nitrogen-Phosphorous-Potassium) . So a fertiilizer labled 5-8-6 would have 5% available nitrogen, 8% available phosphorous, and 6% available potassium. Such a formulation should work for roses.
A fertilizer too rich in nitrogen will cause a plant to grow fast, but may retard flowering. It may also invite pests such as thrips and aphids which thrive on soft new-growth tissues. Most rose formulations have somewhat more phosphorous than nitrogen or potassium.
2) Choose one that is derived principally from organic materials. Remember, you are not just feeding the rose, but are also feeding the soil that supports it. If you feed the soil and keep its flora and fauna flourishing, the soil will augment the health of the rose. Inorganic fertilizers can retard or kill beneficial flora and fauna in the soil, making the rose more dependend on inorganic sources of nutrition.
3) If using non-organic fertilizers, choose slow-release formulas. Fast-release formulations may provide the nutrients fast, but they tend to stress the beneficial organisms in the soil. These organisms do a lot to extract nutrients from the organic and inorganic parts of the soil. The food that the rose uses - the chemicals of the fast-release formulas - are waste products for these beneficial organisms. Use too much, and the soil loses fertility. Then the only way the rose can survive is if you continue to feed it fertilizer. It becomes a fast-release fertilizer junky.
4) Look for fertilizers that claim to build the soil. Kelp and humic acid are some ingredients that can work here. Fertilizers extracted from plants and animals will be better at this than inorganic fertilizers. Alfalfa, peanut hulls, bone meal,and fish meal are some common organic materials.
5) Test the soil and determine what soil ammendments are necessary to provide adequate levels of iron, calcium, potassium, copper, magnesium, and other trace minerals. Then ammend the soil accordingly. Also determine what you need to add to bring the soil to a pH of 6.5 to 7.5. Roses will grow in soils of 6.0 or 8.0, but they will be weakened and more prone to disease and attack by pests when soil is outside the optimum pH range.
Always read and follow the labling. Too much fertilizer can cause serious harm. Strong fertilizers applied directly to the roots could kill the plant. Too much fertilizer could cause other problems. It may make the plant more subject to attack by pests, or it may make it short lived, or it may kill it. Overfertilization ultimately kills the soil, making the soil incapable of supporting plant life until the toxic fertilizer level is drawn down by the slow process of percolation.
Fertilization is an important part of getting the most out of a rose, but it is much less important than most of the other steps in this article. Few roses will up and die without added fertilizer as they might if they receive inadequate sunlight or water. This is especially true of species roses and non-remontant hybrids.
Too many times I have walked into a formal rose garden and felt gagged by the overwhelming smell of chemical spray. 'If this is what I must endure to grow roses,' I swore, I shall never grow roses if the garden must smell so repulsive. I have never determined whether the offensive odor was due to pesticides or fungicides.
Most of our treatment here will be about fungicides. We dismiss pesticides because there are a number of conditions under which pesticide use can increase the number of pests rather than decrease that number. And the toxicity of pesticides is a little less easy to ameliorate. Most pests have corresponding predators or parasites, and those few that do not can be controlled by other means. Japanese beetles, for instance, I trap.
In some parts of the country where the air is dry, the soil is moist, and the sun is bright, roses grow without fungal diseases. I think maybe there is a strip of soil in Texas that meets this requirement, and perhaps there is another strip in California that does. This is where rose breeders and growers are located. It is my guess that much of the rest of the country needs to use sprays to combat fungal diseases, especially on those many disease-prone cultivars bred in California in the middle of the twentieth century.
The good news is that there are a lot of choices. The bad news is that none is perfect.
Other Things to Consider First
Before we talk about sprays it is important to realize that there are a number of things that come first. First, choose a cultivar that is resistant to all fungal diseases, or at least one that is resistant to the ones in your area. East of the rocky mountains rust is not much of a problem. Where the relative humidity rarely gets above 50% blackspot is often not a problem. This means that you may not need to consider rust resistance if you are buying a rose for Connecticut, and you may not need to consider black spot resistance if you are buying a rose for SantaFe or SanDiego.
In any case, remember that choosing a fungal-resistant plant is the first line of defense. It is doubly so if you grow a lot of roses. One rose that is particularly susceptible to a fungal disease can act as a breeding ground for the fungus and accellerate its attack on other plants.
Next consider the soil. Is it the correct pH? Does it provide enough trace minerals? Is it fertile enough? Is there plenty of organic material? Do you see a lot of earthworms crawling around in it when you dig it up? Be sure that the soil provides enough calcium and phoshorous and that the pH of the soil is high enough that these minerals are not bound up by soil acids.
Are there external stresses that predispose the rose to disease? Is it getting enough light? Enough water? Is it getting enough shade to prevent it from being cooked in the midday sun?
If you've done all these things well and your roses are getting fungal diseases, it's time to consider sprays .
There are two general types of sprays; systemmic fungicides and barrier sprays. Systemmic fungicides work by being absorbed into the rose tissue. Then, when a fungal spore sprouts and invades the structure of the plant the fungicide kills the intruder. Barrier sprays work by preventing intimate contact between the fungal spore and the leaf. The spore either does not sprout because it does not have an appropriate environment, or if it sprouts, the structures it has to break into the rose's structure fail.
Before You Start
Remember that sprays can be as toxic to you as to the fungi you are trying to control. Wear appropriate protective clothing. And follow all recommended preparation and safety instructions. Wear goggles and a respirator if you are spraying any man-made chemicals. People have died of incurable liver and kidney diseases from breathing too much of this stuff. Be Careful.
Recently there has been much news about the use of baking soda. Intuitively, it seems to me that if it is a compound we use in cooking, its level of toxicity to humans and most other fauna must not be too bad. Baking soda was tested by the National Rose Society in England. There it was determined that a single spraying at the recommended dosage delayed the onset of blackspot by about two weeks, whereas a single spraying of a conventional petrochemical spray was good for much more than twice that long.
I don't know the recommended dosage for that trial. I used 1 tablespoon per gallon and sometimes get some leaf deformity at this level. I also had protection that lasted well over six weeks. This spray is not recommended for rugosa hybrids; they seem to dislike most sprays.
Another material touted for preventing black spot is extract of neem oil. Neem is a plant native to India. Where it grows in India its twigs are chewed and used sort of like toothbrushes to clean teeth and kill oral bacteria that cause bad breath.
If a systemmic material is sprayed onto the rose, then the highest concentration will be at the surface where the fungus attacks - at least until the first over-head watering or the first rain shower. After this only fungicide that has been absorbed through the plant wall will be active. Most of the treatments listed below are systemmic.
The earliest fungicidal spray is known as Bordeaux mixture. It's a mixture of copper sulfate and calcium carbonate (lime). It is generally held that the copper delivers an effective knockout punch to the fungus, and the lime does little other than perhaps act as a mild surfactant. There are some who imagine that the lime acts in much the same way as sodium bicarbonate. The good news about this mixture is that it is not terribly toxic, it is water soluable, it is inexpensive. The bad news is that copper can build up in the soil and, at least in theory, eventually become toxic. It is possible that at low concentrations the lime and the sulphate ions might have some beneficial actions on soil fertility.
After World War II a number of chemical compounds derived from petroleum were introduced. These had the benefit of being highly toxic to fungi. Unfortunately they had to be delivered in some kind of oil-derivative solvent, for they were not soluable in water. More recently hydrophyllic (water soluable) fungicides have become availble, and these will frequently be more effective than older fungicides against a larger number of fungi. But these compounds are fairly toxic to beneficial flora and fauna, and if used without a mask can lead to serious lung problems. Most rose exhibitionists depend to these compounds. And most rosarians will swear by them.
I have deliberately avoided learning about them because I personally would like to grow a garden without them. If a rose cultivar cannot thrive when helped along by spraying on a benign compound, it is best in the long term if that cultivar goes extinct. I'm afraid that my personal conviction is so strong that I have difficulty recommending them to others.
I recommend that you concentrate on roses that have no need of spraying. (Fragrant red Hybrid Teas, as it turns out, are almost all prone to fungus - Etoile de Hollande might be an exception. And who can grow roses without including at least one fragrant red Hybrid Tea? So maybe just a little spraying is fine. Check out Olympiad)
If you must grow roses that get fungal diseases, start first by using bi-weekly sprays of sodium bicarbonate diluted at the rate of 1 tablespoon per gallon of water. And if you want to use some neem oil, that's okay, too.
If baking soda proves insufficient, I'd advocate using Bordeaux mixture every other season or so, following the label instructions.
If you make your living on the exhibition of roses, then I suppose you should consider using petrochemical fungicides on roses most prone to disease; I can't help but imagine that the roses themselves and the people spraying them would be better off using less of the stuff. Besides being toxic, I find the smell of a chemical-sprayed rose garden repulsive.
Finally, I have to recommend against spraying for pests, except for spot spraying in the direst of emergencies. Preventative spraying for pests done at a low level throughout a large area is perhaps the most effective way of increasing the population of pests. The spray accumulates in pest preditors killing them long before it kills the pests. With fewer predators, the target pests multiply many times faster. In most cases pests can be washed or picked off a rose well enough to to bring it through an infestation. Before long predatory insects will move in and help things along.
So go ahead and spray baking soda and neem oil for fungus prevention, but whatever you spray, always carefully follow the directions and use a dust mask or respirator to prevent inhaling the toxic material. Even chemically inert materials if inhaled over long periods of time can cause lung problems. Asbestos and silica, two of natures's most inert materials have been linked to terminal lung diseases.
How to Prune Roses
We are told that sometime in the middle ages a Monk had a precious grape vine. One winter his very hungry donkey ate the plant back to the hard stems. He was angry and almost had the animal killed for his transgression. But at the last moment he relented. The next year, the plant produced far more grapes than ever before. The monk took this to heart and began to prune the plant regularly. This is how horticultural pruning got started.
We all approach pruning with some trepidation, but any modest amount of pruning will usually improve any well-established rose. Occasionally severe pruning will revitalize an old and tired plant.
A person contemplating pruning a rose plant does well to consider first the fact that roses from the time they evolved, millions of years ago until the time they were broadly cultivated just two or three centuries ago have gone completely without pruning, save for the occasional deadheading that a deer may have performed. In this light it is clear that of all the attentions of a cultivator, pruning may be the least essential.
A person cultivating a rose can do any of the other items on this web page list badly or not at all and in the case of many can succeed in killing the rose. In general, no matter how you approach the pruning task your choice will not be terminal to the rose.
Pruning will not turn a bad rose into a good one. But it certainly can re-invigorate a rose that is a little over-grown. Deadheading prolongs blossoming on remontant roses. Removal of dead wood decreases the chances of disease. Thinning increases the vigor of the remaining canes. Shaping causes the aesthetic appeal of the rose to increase.
When to Prune
The first thing to consider is when to prune. With once-blooming roses it is usually best to prune right after they are finished blooming. This will allow them to build up over the summer for the bloom the next year.
For remontant roses, the very best time to prune is just before the plant leafs out. In zone 6b February is best. March is excellent. Early April is good for moderate pruning. Minor pruning can occur just about any other time.
Pruning stimulates growth, so it is best not to prune after September. Frequently one can tell when a rose is emerging from dormancy by seeing nodules form on the surface of the canes where the canes will be sprouting leaves. Once these nodules have formed, the rose has begun moving sap from the roots into the canes, so it is best to prune before this point. In England and Carolina this might be early January. In the Northeastern US it might be mid February to March.
Deadheading, of course, is done after a rose blooms. If the rose is not remontant, deadheading does little more than make the plant look slightly cleaner. If you like the appearance of hips, then it is important not to deadhead after the fall bloom period.
How to Prune
The second thing to consider is how much to cut off. Every rosarian, has her own ideas on how pruning should be carried out. Some rosarians advocate cutting a plant most of the way to the ground. Others advocate minor trimming. And each cultivar responds differently to pruning. Some thrive on it; others languish after harsh pruning. Several rules of thumb exist: