Content Last Modified: 12 Sep 1996
Written by Bill Chandler.
“The Rose FAQ” © 1996 Bill Chandler. All rights reserved.
Table of Contents
1. Information about this document
- [3.1] My rose has black spots on the leaves, what do I do?
- [3.2] How do I avoid powdery mildew?
- [3.3] How do I get rid of aphids?
- [3.4] What is eating holes in the leaves of my rose?
- 4. Rose Characteristics
- [4.1] Which is the most fragrant rose?
- [4.2] What kind of rose do I have?
- [4.3] Are there any Blue roses?
- [4.4] Are there any Black roses?
- [4.5] What are David Austin roses or English roses?
QUESTIONS AND ANSWERS
1. Information about this document
Welcome to “The Rose FAQ”, a collection of six informative articles about roses. Note that many things related to growing roses will depend upon your local climate. Contact your local rose society or nursery to find out how to grow roses in your area.
[1.2] What’s New with the FAQ
The FAQ has received only minor changes during the last few months.Back to Table of Contents…
2. Rose Care
[2.1] Why won’t my rose bloom?
Here are some of the reasons that roses don’t bloom.
- The rose plant is not getting enough sun. Roses need at least 6 hours of direct sun a day to perform well.
- The rose needs more water. Roses like at least an inch of water per week during the growing season.
- The plant has been given too much fertilizer, especially Nitrogen. Too much fertilizer can either damage the plant or cause it to grow extra leaves and stems at the expense of blooms.
- The rose is a new plant. Don’t expect too much from a plant during its first year.
- Rose is a once blooming variety. This means it will bloom only once a year in the late spring or early summer.
- Soil pH is too low or too high. If the pH is not in the range of 6.0 to 6.8 (ideally 6.5) then nutrient uptake will be reduced, and the plant won’t be getting the food it needs to produce flowers.
- Not enough foliage. If the bush doesn’t have adequate foliage, it can’t produce the food it needs to make new flowers. Inadequate foliage may result from disease or too little fertilizer.
[2.2] How much sun do roses need?
Roses prefer a full day of sun. Give roses at least 6 hours of direct sun a day. Morning sun is especially important because it dries the leaves which helps prevent disease.
[2.3] Which roses can be grown in shade?
In general, roses do poorly in shady conditions. Plants bloom less, are leggy, and are more likely to get diseases. However, many Hybrid Musks and some Albas can tolerate partial shade. The Floribunda “Gruss An Aachen” can be grown in partial shade.
Some other roses that may grow in partial shade are the Rugosas, Iceberg(FB), Zephirine Drouhin (Bourbon), Souvenir du Docteur Jamain (HP) and Madame Plantier.
[2.4] How much water do roses need?
Roses appreciate lots of water. Water generously, at least 1 inch/week, preferably 2 inches/week during growing season. Water every 4‑7 days during the summer when needed. Each bush needs about 4‑5 gallons/week during the hot summer.
Roses get all their food either through their leaves (foliar feeding) or through their roots. The only medium for transporting food is water.
Infrequent deep watering is preferred to frequent light watering to help promote a deep root system. Deep root systems help the rose to survive both droughts, and winter freezes. Frequent, light watering causes roots to form very near the soil surface, making the plant more susceptible to summer ‘baking’ and winter freezes.
Try to avoid getting the leaves wet (which promotes disease) when watering late in the day. However, on hot days wetting the foliage can reduce transpiration and relieves heat stress.
[2.5] How do I deadhead roses?
Deadheading is cutting off flowers as they wither or don’t look as good. Old blooms left on the plant may have been pollinated and may begin to form seed pods (hips). The formation of hips requires a lot of energy from the plant and slows flower production. By preventing the formation of hips, deadheading encourages the rose bush to grow new flowers.
The choice of which spot to deadhead at is influenced by what shape you want the bush to take, and which direction you want a particular cane to grow. Usually, you will want to cut the stem at a 45‑degree angle just above an outward‑facing leaf. Make sure the high side of the cut is the side the leaf set is on.
To deadhead, remove the flower by making a diagonal cut just above the next 5 or 7‑leaf branch down on the stem. The idea is to cut to a bud eye capable of producing a healthy cane. If this would cause too much of the cane to be removed, a 3‑leaf branch can be chosen instead. The first year cut back to the first 3 or 5‑leaf branch. In following years cut far enough down to get to a 5‑leaf branch with a leaf bud that is facing outward. This will open up the plant.
Once blooming roses do not need to be deadheaded. They bloom once and then they are finished blooming for the year. However, once‑blooming roses may be (in fact, should be) pruned after they are finished blooming. They should NOT be pruned in the fall or before they bloom because they bloom on the previous year’s growth.
Stop deadheading as of September 1 in zones 4 and 5. It is a good practice to let the last roses on HT’s produce hips because it makes them more frost hardy. It causes the plant to undergo chemical changes that slow down growth, inhibit blooming and generally prepare for dormancy by focusing its energy on ‘hardening’ the canes. The formation of hips tells the plant that it’s “done its job” and can now rest from its labors.
[2.6] How do I prune roses?
There are three main purposes to be accomplished when pruning roses.
- Keep the plant healthy.
- Encourage the plant to grow in a desired shape.
- Encourage blooming, either more blooms or larger blooms.
The proper tool for most pruning is a sharp clean set of bypass pruners. Anvil pruners should not be used for roses as they crush the stem being cut. A saw or lopping shears may be used to cut very large canes (1/2 inch diameter or greater). All pruning cuts on canes greater than 1/4 inch diameter should be sealed with nail polish or glue to prevent cane borers from entering.
Proper pruning will help keep a rose bush healthy. Dead and diseased wood should be removed as soon as possible to prevent further damage to the bush.
The future shape of the bush can be influenced by the location of each pruning cut. Opening up the bush to increase air circulation will help prevent diseases.
Since rose bushes like to send out a strong lateral cane at the node just below a pruning cut, try to make pruning cuts about 1/4 inch above an “outward” facing leaf bud. By doing this and removing plant material from the center of the bush you will create a more open vase‑shaped plant less susceptible to disease. Whenever two canes cross each other, one can be removed.
Roses can be encouraged to bloom better if thin, weak and non‑productive wood is removed to allow the plant to concentrate its blooming on the larger healthier canes. Generally with Hybrid Teas any cane thinner than a pencil should be removed. Plants may be pruned hard to encourage larger blooms but fewer blooms (commonly done with Hybrid Teas.) Or the plant may be pruned lightly and allowed to grow larger and produce more flowers that are smaller (commonly done with some shrub roses.) Prune first year plants only lightly to allow them to concentrate on establishing a strong root system.
[2.7] How do I protect my rose bushes during the winter?
Local advice is preferred for this question, but here are some general guidelines for winter care of rose bushes for those living in colder climates. The major dangers to the plant in winter are the drying of the wind, the effect of alternate thawing and freezing cycles on the plant when winter temperatures fluctuate, the inability of the plant to take in water if the soil is frozen, and damage from the cold itself to the canes and bud union.
- If you live in an area with harsh winters, plant cold‑hardy roses. Your choices are more restricted that way, but you will save yourself a lot of work and heartbreak. Many once blooming old roses are very cold‑hardy. Of the repeat blooomers, rugosas are rock‑hardy, and many Austins and other shrub roses will do okay. Many yellow and lavender roses are especially tender. Unfortunately cold‑hardiness is not an exact science; conditions such as wind affect roses severely in cold weather (by drying them out), and so zone ratings are only a first approximation. Beware of books that rate roses ‘cold hardy’ or ‘not cold hardy’ — they are likely referring to conditions in the UK, which has mild winters. Beware also of catalogs that overrate cold‑hardiness because they want to move more product.
- When in doubt, plant own‑root roses. If they die back to the ground in a particularly severe winter, they will grow back from the roots fairly quickly. This advice is not applicable to once‑bloomers, because these usually flower only on the last year’s canes. Own‑root Old Roses and English roses are available. Hybrid Teas are almost always sold as grafted plants, and it is difficult to find own‑root plants.
- In the fall, reduce the amount of Nitrogen fertilizer used. This, combined with lower temperatures, will slow the production of new tender growth, and will allow the existing growth to harden off.
- Stop deadheading about September 1 for zones 4 and 5. This will allow the plant to form hips. The formation of hips encourages the plant to slow down growth, slow blooming, and harden the canes, all preparing the plant for dormancy.
- Understanding rose dormancy will help to determine the proper time to prune during the period from late Fall to early Spring. During dormancy, the sap has left the canes and the canes are simply empty tubes of cellulose. Pruning too early (before the sap runs back) cuts some of the nutrients out, so you must be sure the plant is dormant before fall (winter) pruning.Winter dieback generally occurs from the end of the branches (canes). Pruning removes the available length that can die back before reaching the ground. Also, pruning a semidormant plant stimulates growth and sap flow in the pruned region. For a plant going dormant, this is bad because it inhibits dormancy. For a plant waking up (springtime) it’s good because it stimulates growth. Ideally pruning should occur before sap is fully flowing.
- To prevent disease/fungus from overwintering, clean the rose bed by removing leaves and other debris. Spray the bush with dormant oil to kill bacteria on the bush and on the ground.
- Protect the crown of the rose. This is critical since the crown is where you want the new canes to come from. There are several methods of protection to choose from.
- Cover the bed at least a foot deep with tree leaves. Do not use rose leaves as they may harbor disease. Oak leaves are best as they seem to drain better.
- Cover the bed with straw.
- Use rose cones.
- Make a mound with soil or mulch to cover the crown.
- Wrap the whole plant in burlap if necessary, in addition to one of above methods of protecting the crown. Timing is important. Covering the rose too early is unwise as it may prevent the rose from hardening properly and will slow the onset of dormancy. Covering the rose too late may risk damage from the cold.
- Climbers or long canes may benefit from being tied to avoid thrashing from the wind. Canes may be protected from drying winter winds by wrapping them in burlap with a layer of straw for insulation. In severe climates long canes may need to be tied and buried.
- Keep the soil well‑drained, especially as the spring rains come.
[3.1] My rose has black spots on the leaves, what do I do?
Blackspot is a fungus that causes black spots about 1/16 to 1/2 inches in diameter to form on the leaves and sometimes stems. The infected leaves later turn yellow around the spots and eventually fall from the plant. In bad cases, blackspot can severely defoliate a rose bush. The conditions that promote blackspot are wet leaves, splashing water and warm temperatures.
Here are some ways to combat blackspot. Most of these methods also apply to preventing and treating powdery mildew.
- Pick a variety of rose resistant to blackspot. For example, many Rugosas are quite resistant to blackspot.
- Use watering methods that don’t get the leaves wet: drip watering, using a soaker hose, or just soaking the ground with a light stream from a garden hose. If overhead watering is used, do so in the morning so the leaves can dry off before evening.
- Remove ALL diseased leaves from the plant or ground immediately to prevent further spreading of the disease. Infected leaves never get better, they just spread the disease. Prune infected canes severely in late winter.
- Prune away crossing canes and open the center of the bush to allow sunlight and airflow to more of the plant.
- Blackspot is transmitted by water splash. Remove leaves close to the ground (the first 6‑8 inches) which are more susceptible to getting water splashed on them. Mulch well to minimize water splashing onto leaves. If a plant had a lot of blackspot the previous year, remove the old mulch in early Spring, allow the area to dry and replace with clean new mulch.
- Keep the plant well watered. A weak or stressed plant is more susceptible to disease.
Preventative spray treatments for blackspot.
- Chemical fungicides can be very effective in preventing blackspot and are usually applied every 7‑14 days. It is most important to spray the undersides of the leaves. FOLLOW THE LABEL DIRECTIONS EXACTLY. Too much fungicide can cause leaf burn. It is best if rose plants are watered well before spraying. Spraying during very hot weather can damage leaves. Early morning and early evening are the best times to spray. Avoid spraying under windy conditions. READ THE PRODUCT LABEL carefully and wear proper equipment when spraying, such as eye, mouth and nose protection.
- Since a single fungicide may not completely wipe out all the fungi, using that fungicide over and over may actually cause fungus to build up a resistance to that fungicide. Alternating between two fungicides, such as Triforine (Funginex) and Daconil, is recommended to keep resistant fungi from building up. Fungicides generally can prevent blackspot, but do not cure an existing case of blackspot.
- Some gardeners wishing to avoid fungicide use have tried using baking soda to help prevent blackspot with mixed results. Combine 1 1/2 tablespoon baking soda and either 2 tablespoons horticultural oil or a few drops of Ivory liquid soap with 1 gallon of water.Mix as well as possible, and spray both sides of the leaves once a week. The Ivory liquid helps the baking soda stick to the leaves. Reapply after a rain. Baking soda changes the P.H. of the leaves, helping to prevent blackspot. Spraying with baking soda works for some gardeners, but others have found that baking soda is not effective enough in their climate.
[3.2] How do I avoid powdery mildew?
This fungus forms a powdery white or grayish coating on the upper surface of young leaves and sometimes on the buds. Infected leaves crumple and become distorted.
Unlike blackspot, wet conditions actually inhibit the development of powdery mildew. It can not reproduce in water. It thrives during high humidity but forms on dry leaves. Warm dry days, cool dry nights are ideal for powdery mildew.
One of the best ways to avoid powdery mildew is to keep things as airy as possible. Roses planted too close to a wall may not get enough airflow. Prune away crossing canes and open the center of the bush to allow sunlight and airflow.
Also, spraying the foliage with a mixture of 1 tablespoon baking soda per 1 gallon of water can be effective.
[3.3] How do I get rid of aphids?
Aphids are tiny insects about a 1/16 to 1/8 inches long, usually light green, red or black. They come in the spring and damage tender new growth.
A hard spray of water from the hose will help remove aphid infestations. Aphids reproduce quickly and this may need to be repeated every couple days for a couple weeks.
Aphids have a mutually beneficial relationship with ants, so ants need to be controlled if aphids are to be controlled. Ladybugs are a natural predator of aphids and can be used to control aphids. If ladybugs are purchased, water the area well and release the ladybugs around sunset to discourage them from leaving.
[3.4] What is eating holes in the leaves of my rose?
Leaf cutter bees cut semi‑circle shaped holes in the leaves of roses. They pose no real threat to rose health, but they drive exhibitors crazy.
4. Rose Characteristics
[4.1] Which is the most fragrant rose?
Here is a list of some very fragrant roses. (HT means hybrid tea.)
- HT: Double Delight (mentioned most often), spicey, red‑white bicolor
- HT: Fragrant Cloud, reddish‑orange
- HT: Mr. Lincoln, dark red
- HT: Crimson Glory, red
- HT: Chrysler Imperial, red
- HT: Papa Meilland, dark red
- HT: Perfume Delight, pink
- HT: Secret
- ER: Gertrude Jekyll, pink
- ER: Othello, dark red
- Alba: Felicite Parmentier, once‑blooming
- Damask: Mme. Hardy, white, once‑blooming
- Tea: Sombreuil, cream‑white
- Bourbon: Souvenir de la Malmasion
- HP: Souvenir du Dr Jamain
Many of the David Austin roses are fragrant. So are many of the Old Roses, such as the Damasks.
[4.2] What kind of rose do I have?
When posting this question to the newsgroup, include as much information about the rose as possible, such as the following:
- What kind of rose is it? (climber, Hybrid Tea, Old Rose, Species, etc.)
- Aproximate plant size (4ft tall by 4ft wide)
- Flower color, bud color, flower size (e.g. 4 inch diameter)
- Approximate number of petals per flower
- Foliage color (light, medium, or dark green)
- Foliage description (dull, shiny, leathery, large, small, etc.)
- How many leaflets per leaf on average (3,5,7, etc.)
- Once blooming (blooms once a year) or repeat blooming
- Thorns (many, few, large, hooked, straight)
- Fragrance (none, light, heavy, spicy, fruity, tea, etc.)
[4.3] Are there any Blue roses?
Though highly sought after, no blue roses exist yet. Some roses are advertised as blue, but they are actually lavender or something. Most lavender roses are difficult to grow and are quite susceptible to disease.
Some of the bluer roses are Blue Girl, Blue Jay(HT), and Reine des Violettes(HP). A couple of true purple roses are Cardinal de Richelieu and Veilchenblau.
The genetics are just not there for producing a true blue color in roses. It will probably be necessary to use gene splicing to produce the first blue rose.
[4.4] Are there any Black roses?
No true black roses exist. Some roses sold as black roses are actually dark red or maroon. The petals of many of these dark red roses tend to sunburn easily. To see that a rose is not truly black, hold it up next to a piece of black construction paper. To make a dark red rose appear blacker, put its stem in water that has black ink in it.
Below is an incomplete list of some roses that have been mentioned when black roses are discussed. Next to some of the roses a very subjective description of the color is given.
- Black Jade: dark red miniature
- Cardinal de Richelieu: dark purple Gallica
- Chateau de Clos-Vougeot: HT, deep red blossoms, blackish highlights, poor growth
- Francis Dubreuil: Tea rose
- Guinee: very, very dark red
- Mr. Lincoln: HT, dark red
- Nuits de Young: purple Moss rose
- Oklahoma: HT, deep crimson
- Souvenir du Dr Jamain: Hybrid Perpetual, dark red/maroon
- Sympathie: deep red climber
- Taboo: Popular dark rose that has deep red flowers with darker edges. It reportedly has nearly black buds.
- The Prince: English rose, very, very dark red/purple
- Tuscany Superb: Gallica, deep maroon velvet
[4.5] What are David Austin roses or English roses?
In 1969, English Roses, often called David Austin Roses, were introduced by the English rose hybridizer David Austin.
David Austin tried to create roses that combine the best elements of Old Roses (roses varieties from before 1867) and Modern Roses (such as Hybrid Teas, Floribundas and Grandifloras). Most English Roses have flowers resembling Old Rose flowers, cupped and rosette‑shaped old‑fashioned flowers, usually with many petals. English Roses generally repeat flower well, like the Hybrid Teas and other Modern Roses. English Roses are available in a wide variety of colors, such as yellows not very common in Old Roses. Many English Roses have the strong fragrances of some of the Old Roses.
There is a FAQ article called ‘English Roses’ which is part 6/6 of the FAQ.
[5.1] How do I propagate roses?
There are two primary ways to propagate roses. Asexual reproduction is usually used to produce a duplicate of the parent plant. Sexual reproduction, i.e. growing roses from seed, is primarily used to create new varieties of roses.
Common methods of asexual propagation of roses are softwood rooting, hardwood rooting, and bud grafting. Limited space permits only a brief description of softwood rooting.
Old Roses, English Roses and Miniatures are generally good candidates for rooting cuttings because they usually grow vigorously on their own roots. Modern Roses such as Hybrid Teas and Floribundas are usually sold budded onto different rootstock. Some Modern Roses do grow vigorously on their own roots, while others do not. Below is a description of softwood rooting from Karen Baldwin with some changes.
ROSE PROPAGATION À LA ZIPLOC® BAGGIES
MAKING THE CUTTING
- Preferably take a cutting on which the bloom is barely spent, so that all the petals have just recently dropped off. It is okay to take a cutting earlier, but at least make sure color is showing in the bud. These are indications of the maturity of the wood in the stem — you want something in between the extremes of greenwood and hardwood.
- Try to have at least four separate leafsets under the bloom, and a five‑leaflet set at the bottom of the cutting. (Each spot where the leafsets meet the stem forms a “node,” where the bud eyes are, and from which roots can form. Hybrid teas tend to have fewer “nodes” spaced farther apart than Old World roses, and thus require a longer cutting, generally speaking). Make a clean bottom cut with a sharp, clean pruning tool 1″ below the last node. Try to leave about 1/2″ of cane above the top leafset.
- Keep your cuttings fresh in water while you gather more, until you’re ready to plant them.
PLANTING THE CUTTING:
- Fill a 1‑gallon Ziploc® baggie 1/4 to 1/3 full (about 3″) with STERILE loose potting mix. (e.g. 1/2 peter’s potting soil and 1/2 vermiculite).
A 2‑gallon Ziploc® baggie may be better since it will give the leaves more room, but use the same depth of soil you’d use in a 1‑gallon baggie, since you’ll be watching for roots growing through it, later.
- Moisten the mix but do not make it extremely wet. Use 1 tsp. miracle gro per 1 quart of water, to provide some initial nutrients (which may help avoid yellowing and leaf‑drop). With your hands, firm the soil down well, within the baggie. The soil should be very damp, but there should be no standing water in the bottom.
- Snip off the stem a little above the top‑most leaf set (i.e., remove the flowering part). Try to leave about 1/2″ of cane above the top leafset.
- Strip off the bottom two sets of leaves (where the stem will be pushed into the soil).
- Score the bottom part of the stem along its length (vertically) for an inch or so. (An exacto‑knife works nicely for this purpose, but fingernails will do fine.) Roots will form along this score.
- Dip scored end of cutting into rooting compound, a couple inches deep. Knock off the excess (you can get too thick a layer). Stick the cutting a couple of inches into the soil.
- If insects have eaten the leaves during previous rooting attempts, you may wish sprinkle a very small amount of diazinon or other insecticide on the soil surface. Be especially careful if you are using chemicals indoors.
- Mist the cutting and the interior surfaces of the baggie with a spray bottle filled with the following mix (to avoid fungus and mildew growth in the closed “terrarium” environment). Do not use spraycan fungicides or insecticides … in the closed environment, the chemicals can overwhelm then kill a new young plant.
- 1 quart water
- 1 tsp. miracle gro
- 1 tsp. baking soda (no more!)
- 2‑3 drops dishwashing liquid (to make it cling)
- Pull the ZipLoc® baggie almost shut. Breathe into it until it expands kinda like a balloon, and zip it the rest of the way closed. (Keep it closed unless it deflates enough to warrant breathing into it again.)
- Put in bright, INDIRECT light – (e.g., behind sheers in a southeast‑facing window) WARNING!!! if it gets direct sun or too much heat it will scorch (eventually turning black) and likely die! You may have to experiment a bit to find the best exposure; you might hedge your bets by placing some in different locations until you find the best spot for your house.
- Clear away any leaves that might drop from the stem, reinflating the baggie after removing them.
POTTING THE CUTTING:
- Look for roots along the bottom of the baggie in two or three weeks. A few stubborn ones may take six weeks, and there is a report of one incredibly obstinate plant that took over 10 weeks!
- Acclimation to air outside the bag is tricky. To be careful,
- When you see some top growth, unzip the baggie just a little for a few hours the first day, then seal it up again.
- For the next few days, unzip the baggie the same amount, but leave it open for a few more hours each day.
- Next, leave it open all the time, but increase the amount the bag is unzipped each day for about a week, until it’s fully open. Don’t rush it.
- Put good soil into a 1‑gallon pot, leaving room for the addition of the new plant and its soil. Place the baggie atop the soil, and cut the plastic away (this can be slightly tricky). Firm the soil around the plant only very lightly.
- Keep the same lighting in the same location (protected from too much direct sun) for a week, leaving the cutting unmolested to give its disturbed roots a chance to heal.
- After they have spent a week in their pots, you can either move them into more light inside for the first winter), or (preferably) move them outside.
- When moved outside, set them in indirect sun at first, bright but shaded, and leave them there for a week. (If your area gets cold at night, you may need to move them inside at night for a while.) The next week, move the plant bit by bit toward and then into full sun. (Note: Gro‑lights don’t normally put out nearly enough light for roses, though it can probably be done.)
- When kept inside for their first winter, especially in zones 5 and below, place them in a spot where they’ll get more light. When planted outside in the same summer they were rooted, even with a heavy mulch, many more will be lost to winter kill since the new little roses won’t always have enough roots to carry them through. Also, chinooks (intense, warm winds) do their damage too. By keeping them inside for their first winter, and planting them in the spring, they will be better‑established by the next fall.
- Plant late enough to avoid those nasty springs that get warm, causing the roses to break dormancy, only to follow up with a hard freeze!
- Remember that your rose will grow in size; prepare a good‑sized area of soil with added organic material as appropriate to your locale.
[5.2] What is an ARS rating?
An ARS (American Rose Society) rating is a yearly rating from 1 (worst) to 10 (best) given to a variety of rose. This is a U.S. national rating, combining several district ratings. The district ratings are an average of individual ratings given by rose growers, beginners to experienced.
The ARS ratings are print yearly in the “Handbook for Selecting Roses”. It can be obtained from the address below:
- American Rose Society
- P.O. Box 30,000
- Shreveport, LA 71130‑0030
- phone: 1‑800‑637‑6534
The American Rose Society has an excellent World Wide Web page at https://www.rose.org/.