growing roses in the Pacific Northwest

I would like more information on Rosa chinensis ‘Mutabilis’,
particularly regarding how it performs in a Seattle garden. I am most
concerned about black spot and any other diseases.

I am currently growing this rose for the first time, and it is blooming
profusely. I have needed to keep on top of the aphids (hand-squishing),
and there are a few yellowed leaves which drop (and which I have been
picking up and destroying as soon as I see them). Here is what the book
Roses for the Pacific Northwest by Christine Allen (Steller Press, 1999)
has to say about this rose:

Few old roses flower so continuously–cold weather merely turns the buds
a paler hue and, although they don’t then open, they remain fresh-looking
on the bush for weeks. It hates cold wind, but will take a surprising
amount of shade, forming an open, leafy shrub with soft red stems and
red-tinged foliage, impervious to disease.

I would not go as far as to say it is impervious to disease,
but my impression is that it is relatively disease-resistant. I am truly
enjoying the look and fragrance of this rose in my garden. Links to additional information:

An article by Valerie Easton in the Seattle Times

managing black spots on roses

What can I do about black spot on my roses? I heard that burying banana peels in the soil might help.

According to The Organic Gardener’s Handbook of Natural Insect and Disease Control (edited by Barbara Ellis; Rodale Press, 1996), there are several steps to dealing with black spot on your roses. First, avoid wetting the leaves, and do not handle the plants when foliage is wet. Prune the plants to make sure there is good air circulation. Make sure the roses are in sun, and are not shaded by large shrubs or trees. Avoid using high-nitrogen fertilizers, and only fertilize based on a soil test’s indications. If you expect an appearance of black spot (based on past experience), spray plants weekly with sulfur or fungicidal soap. Once you see symptoms, it is hard to control black spot. Remove and dispose of any affected parts of the plant (don’t compost). Make a solution of 1 teaspoon baking soda in a quart of water, and spray the infected plants well.

University of California, Davis’s Integrated Pest Management website says the following about black spot (Diplocarpon rosae):

“The fungus requires free water to reproduce and grow, so leaves should not be allowed to remain wet for more than 7 hours. (When hosing off aphids, do it in the morning so leaves have a chance to dry by midday.) Provide good air circulation around bushes. Remove fallen leaves and other infested material and prune out infected stems during the dormant season. (…) Miniature roses are more susceptible than other types, although a few varieties are reliably resistant to all strains of black spot.(…) A combination of sodium bicarbonate or potassium bicarbonate plus horticultural oil (as discussed above under “Powdery mildew”) or neem oil has also been shown to be effective in reducing black spot.”

Brooklyn Botanic Garden has information on natural disease control, including the following:
“Baking soda (sodium bicarbonate) is non-toxic, readily available, and very inexpensive. It can be effective against powdery mildew and somewhat useful against black spot. If you repeatedly spray leaves with bicarbonate, though, it will eventually reach the soil below, where it can accumulate and lead to slower plant growth. Bicarbonate can form insoluble particles with calcium and magnesium ions when it concentrates in the soil, making these important nutrients unavailable to plants. High levels can also prevent plants from absorbing iron and can lead to chlorosis.
Bicarbonate is most likely to build to damaging levels in drought-stressed areas where there is little rain to flush it away. It is also likely to build up when applied in a small area, and when used in conjunction with drip-type irrigation. Garden situations are so complex that it is hard to predict the point at which you will see adverse effects. Stop applying bicarbonate sprays, however, at the first sign of plant damage or lower quality blooms.”

Brooklyn Botanic Garden also mentions a beneficial bacterium which may provide some help:
“Preliminary research shows that the beneficial bacterium Bacillus laterosporus (sold as Rose Flora) is as effective at protecting black spot-susceptible rose cultivars as some chemical fungicides. It probably protects against black spot through competition, but this agent is still relatively new and experiments detailing its mode of action have not been completed. As a ground spray, it can help control new sources of black spot infection. As a foliar spray, it seems to be more effective when mixed with the antitranspirant sold commercially as Wilt-Pruf. The powdered formulation can cause eye irritation, so use eye protection when mixing solutions and applying.”

About the practice of using banana peels to control black spot on roses, I found the following item on Gardening Folklore from Ohio State University Extension, which suggests the peels might be a good fertilizer, but does not say they will control the fungal problem.
Excerpt:

“Placing several banana peels in the planting hole was popular among rose growers in the 18th century, but they had no idea why the peels seemed to yield healthier roses. Today, we know that banana peels contained many useful nutrients, including calcium, magnesium, sulfur, phosphates and sodium. The peels rot quickly which means these nutrients are readily available to the plant.”

Some sources recommend using compost tea or milk sprays on black spot-affected leaves, but Washington State University Horticulture Professor Linda Chalker-Scott dismisses these methods as ineffective. She also states in an article in Master Gardener magazine (Spring 2009) that baking soda sprays may only be of limited efficacy in combatting black spot. Studies have shown that it works better when combined with horticultural oil.

To sum up, I would pay attention to the cultural practices (not wetting the leaves, etc.). You can try a baking soda spray (always test on a small area of the plant first), but it may not have lasting power as a treatment. Prof. Chalker-Scott mentions that coarse organic mulch (such as wood chips) reduces incidence of black spot, so you may want to adopt this mulching practice.

propagating roses from cuttings

I am trying to grow roses from cuttings. They are sprouting little leaves but are still under empty soda containers for humidity. When I took a few out of the containers, they promptly shriveled up and died. Should I leave them for another month? I don’t want to tug to see if they have roots, as that will disturb them. Do I apply foliar fertilizer?

I have listed a few useful webpages about propagating roses from cuttings below.

To answer your question about leaving them under cover, I think you probably should leave them for at least a brief while, given the very cold weather. I don’t think you need to apply foliar fertilizer at this stage. The resources below should offer some additional advice on caring for your cuttings.

John Fisher’s book, The Companion to Roses (Salem House Publishers, 1986), says that roses grown from cuttings may take longer to flower than those budded on rootstock, but (if they survive the process) they may live longer and will not sucker. Some roses are easier to propagate from cuttings, such as ramblers and Rosa rugosa, as well as some climbing roses and large-flowered roses.

According to Fisher, cuttings can be taken as early as August. You should choose young shoots with ripened wood that have borne flowers, and lateral shoots rather than leaders. He recommends selecting those shoots growing low on the shady side of the plant, and those with leaf joints that are close together. Make a clean cut just below a leaf joint. The cutting should be about 9 inches long with 2 leaf joints in the top 3 inches. Cut off the tip that has borne the flower and the leaf immediately underneath it. Remove leaves (but not buds) on the lower 2/3 of the cutting, since this is the part that will be planted in the ground. The soil should be a mix of loam and sand mixed down to a depth of about 9 inches, in a pot or V-shaped trench. Before planting the cutting, poke a hole in the soil for it to go into. Moisten the bottom end of the cutting with a cotton ball, and dip it in rooting hormone (or willow water). Put the cutting in the soil and press the soil around it firmly. If you need to protect it from frost, cover it with leaves or sacking during the winter. By summer, it should have formed a root, and should be ready to plant in the fall.

The information below may differ somewhat from these directions, but you may get a general sense of how your methods compare, and whether you want to try any of the methods suggested.

University of California Cooperative Extension

Morrison Gardens

The Southern Garden

Disease-resistant roses for the PNW

My neighbor wants a rose, but it will be planted in an organic
garden. It is a sunny warm spot (for Seattle), but I think disease
resistance is a must. What is a source for disease resistant roses
for our climate? Also, does growing clematis on a climbing rose limit its disease
resistance?

The reason that clematis and rose make good companions has to do with the
rose providing the structure the clematis needs, and the pairing allowing
for interesting combinations of color and shape, rather than one
providing disease resistance to the other.

Generally, the most disease-resistant roses are species roses, but there
are additional choices.

This list from Pacific Northwest Pest managment Handbook lists resistant roses.

This article from Washington State University Extension is entitled “Disease-Resistant Roses for the Puget Sound Area.”

There are several excellent books on growing roses in our area:

North Coast Roses : For the Maritime Northwest Gardener by Rhonda Massingham Hart (Seattle : Sasquatch Books, c1993)

Jackson & Perkins Beautiful Roses Made Easy : Northwestern Edition by Teri
Dunn & Ciscoe Morris. (Nashville, Tenn. : Cool Springs Press, 2004)

Roses for the Pacific Northwest by Christine Allen (Vancouver : Steller Press, 1999)

Roses for Washington and Oregon by Brad Jalbert, Laura Peters (Edmonton : Lone Pine Pub., 2003)

Roses for the Inland Northwest. Washington State University Extension ; [Washington, D.C.] : U.S. Dept. of Agriculture, [2004])

This book is a comprehensive guide to combining clematis and roses:
The Rose and the Clematis As Good Companions by John Howells ; photographs
by the author ; flower arrangements by Ola Howells (Woodbridge : Garden Art Press, 1996)

All of these titles are available in the Miller Library.

loss of fragrance in roses

I wonder why my roses have lost their fragrance. My ‘Double Delight’ roses used to have a good smell, and now the flowers are bigger and there is no fragrance.

It does seem mysterious that a once-fragrant rose should lose all fragrance. There are many factors which might cause the perceived lack of scent. According to The Graham Stuart Thomas Rose Book (Timber Press, 1994), rose scent itself is complex, and is composed mainly of geraniol along with many other substances. It is mainly released from tiny cells on the surface of the petals: “Scent is produced mainly in the petals and is given forth when the growth of the flower and the atmospheric conditions are right. From this it will be seen why double roses have more volume of scent than singles […] scent is especially apparent in most flowers when the air is neither too cold nor too hot […] In extreme conditions, such as wilting, extra scent may be released […] Usually the best fragrance is obtained from a newly opened flower growing on a healthy, well-established plant on a windless day when growth is exuberant […] we may expect fragrance to be at its best on a day when the air is warm and moist rather than dry, when the plant will be functioning well. It is not that moist air conveys better than dry, but that the plant is giving it forth in greatest quantity.”

From the above, you may want to consider the following

When you discovered the rose had no scent, were the atmospheric conditions optimal for the release of scent?
If scent is most prominent on healthy plants, are there any underlying reasons (pests, diseases, cultural problems such as overwatering, poor soil, etc.) the plant might not be at its strongest?

Other things to consider:
Environmental pollutants affect not only our sense of smell, but the fragrance emitted by flowers, as this 2008 University of Virginia study describes:
“‘The scent molecules produced by flowers in a less polluted environment, such as in the 1800s, could travel for roughly 1,000 to 1,200 meters; but in today’s polluted environment downwind of major cities, they may travel only 200 to 300 meters,’ said Jose D. Fuentes, a professor of environmental sciences at the University of Virginia and a co-author of the study. ‘This makes it increasingly difficult for pollinators to locate the flowers.’

The result, potentially, is a vicious cycle where pollinators struggle to find enough food to sustain their populations, and populations of flowering plants, in turn, do not get pollinated sufficiently to proliferate and diversify.”

Another thing that you might ask is whether your rose was grafted, and perhaps you are getting a different rose coming up from the graft. The loss of fragrance and the different appearance of the flowers makes me wonder if this could be what is happening.

on disbudding roses

I’ve been removing all the small, spiky buds and leaving the main developing bud on my rose (I think it’s a Floribunda, but I’m not sure). My husband told me I was doing the wrong thing. Is he right? I thought I’d heard that removing the ancillary buds would give me a better-looking single bloom, like the long-stemmed roses you see in displays.

I’m a lazy grower of roses, and so it would not occur to me to disbud in order to have one single larger rose. But you are correct that this is in fact done in some cases. I found a brief item in Rose Magazine online (now archived) which illustrates the practice (it seems to be used mainly for roses being used in displays, where a kind of perfection is desired). Note the following, about Floribunda roses, which describes exactly the opposite procedure:
“On roses that produce multiple blooms, like those of Floribundas or Grandifloras, it is the terminal bud that is removed. On these roses, the terminal bud will open first. By the time surrounding blooms form the terminal rose is almost fully blown. The result is a floral spray with a hole in the center. By removing this terminal bud early in its formation, the rose’s energy goes toward those that remain. The result is a floral spray that is full — without the hole in the center.”

The website of the Desert Rose Society also describes disbudding.

“The practice of disbudding applied to roses can produce some impressive results in the size and quality of the bloom. This is how you get those big lovely long-stemmed roses. When disbudding for one bloom to a stem roses, such as hybrid teas, you remove the side buds that develop at the leaf axils below the main bloom. This is done by rubbing the tiny buds out from of the angle created between the leaf and stem. I find my thumb works best for getting right in there. The earlier you do this in the development of the side buds the better, for you will leave less of a disbudding scar or black stub. How many buds do I remove? Enough that you will have the desired stem length with no side buds. In a rose show, a single bloom on a stem will be disqualified if it has side buds, with the exception of old garden roses and shrub roses.

When disbudding roses that bloom in clusters like the floribundas, it is a little different process. You have to look at the stem and see how many buds there are. If there is a central bud and only one or two side buds, remove the side buds and go for a one bloom stem. When presented with many buds and a central bud, remove the central bud and make this stem into a spray (or cluster) of blooms. The central bud would normally bloom first and be faded when the rest of the buds open. A spray, for show purposes, must contain two or more blossoms and three or more blossoms are best. If trying for a spray for show be sure that the multiple buds have at least three buds of about the same size so they will be open at the same time to give the desired blossom count.”

For the meticulous home gardener or professional rose exhibitor, you may find this information on the American Rose Society’s judging criteria of interest.

To sum up, the answer to your question about whether or not to disbud seems purely an aesthetic choice.

managing rose slug and rose mosaic

My roses were diagnosed with both rose slug and rose mosaic. I would like to know your thoughts about treatment of these conditions, as it was suggested that I just remove affected leaves, and I am looking for a more effective solution.

I will summarize what Christine Allen’s Roses for the Pacific Northwest (Steller Press, 1999) says about these two problems:

Mosaic virus:
This disease infected the roots of your rose when the plant was grafted; the symptoms do no show up for a year or two. The problem is widespread anywhere that rootstocks are developed from cuttings (rather than seed). (In Canada, apparently, most rootstocks are grown from seed, so they have far less of a problem with the disease.) The disease is incurable, and affected plants will have yellow patterning on their foliage. Other plants in the garden cannot “catch” the disease. Sometimes the symptoms disappear by midsummer, but recur the following spring.

Rose slug:
The greenish-white worms are actually sawfly larvae, and they can skeletonize leaves. They aren’t caterpillars, so controls that are used for caterpillars (such as Bt) won’t help. Insecticidal soaps can kill them, but only by making contact, so this means repeated spraying. It is best to do this in early evening when the larvae are most active, and may be seen on the top surfaces of the leaves. Pyrethrins are effective, but they also are acutely toxic to aquatic life, moderately toxic to birds, and may kill beneficial insects such as honeybees [my comments, not the author’s], so they should be a choice of last resort. The Environmental Protection Agency has additional information on pyrethroids and pyrethrin.

To prevent or mitigate rose slugs, clean up leaf litter and other debris several times a season to eliminate pupae and interrupt the life cycle. Hoe the soil gently and not deeply, and apply annual mulch early in the year.

on overwintering miniature tea roses

Do I need to take my miniature tea roses indoors for the winter?

Your message doesn’t mention where you live, so I don’t know how cold
your winters are. Bringing your roses into the house can be problematic,
because we tend to keep our homes too warm for the plant, which wants to
go dormant in winter. A cold but sheltered spot may be a better choice.
If you live in the Pacific Northwest, you can keep your roses outdoors
year-round. Christine Allen’s Roses for the Pacific Northwest (Steller
Press, 1999) says that miniature roses are extremely hardy, hardier than
many larger roses. They can survive winter in an unprotected pot unless
the soil freezes all the way through.

The following information from New Mexico State University Extension offers similar advice. Excerpt:

“The miniature rose is often hardier than the common hybrid tea rose, so
it will survive but not bloom through the winter in most parts of New
Mexico. It requires a cool, dormant period and will do poorly if brought
indoors where it will stay warm. I have also noticed that if it is
indoors during the winter, it is often attacked and even killed by spider
mites. Other insects also become a problem when plants are indoors.

“You have several options. One is to leave it in its pot and keep it
outside in a protected location. Plants in pots are more subject to
freezing during the winter because the soil in the pot can freeze
completely and drop to a lower temperature than soil in the ground unless
the pot is kept in a protected location. Plants in the ground may have
the soil freeze around the base of the plant, but the roots are often not
frozen. A sunny location that allows daily warming and nightly freezing
of the soil in the pot is not good. You will also need to make sure that
the soil in the pot does not dry completely during the winter. Roses need
some moisture in the soil around their roots even in the winter. Soil in
flower pots dries more quickly than in the ground.

“Another option is to plant the rose in the soil where the soil
temperature will remain more moderate and the soil will dry slowly. It is
late in the season for this, but it can be done. Don’t let it dry after
planting, and by applying a layer of organic mulch (bark, straw, etc.)
around the base of the plant, you can help maintain moderate temperatures
and prevent sudden temperature changes in the root zone.

“Finally, you can keep the rose in a protected, cool location, allowing it
to become dormant for several months, then prune it and bring it indoors
to begin blooming early in the spring. This allows it to have its winter
rest, but you can enjoy its flowering earlier than if it stayed outside.
Replanting in a large pot may be helpful to allow more root growth. A
miniature rose is called miniature not for the size of the plant but for
the size of the flowers. Some miniature roses can become fairly large
plants and need a large root zone to support growth and flowering. That
is why planting outdoors may be the best choice in the long run, but
repotting it allows a potentially useful compromise.”

about Floribunda roses

I was wondering if you could send me information about Floribunda roses. I’m doing a research paper.

We have a large selection of books on roses here in the Elisabeth C.
Miller Library. You are welcome to come in and browse as well as borrow
books.

The Seattle Rose Society says the following about Floribunda roses:
Floribunda roses combine the best aspects of their parent plants: the
Hybrid Tea rose and Polyantha rose. They receive their flower form and
foliage from the Hybrid Tea while taking after the Polyantha in increased
hardiness and exuberance of blooms. This link is to their lists of recommended roses for the Puget Sound region, including the best Floribundas.

Here are additional links which may be useful.

Roses and everything rose & gardening related

American Rose Society

Most of our books have at least a little information on Floribundas, but
none is specifically and exclusively about them. I recommend The
Companion to Roses by John Fisher (Salem House, 1987) for history of rose
classification, and Jeff Cox’s Landscape with Roses (Taunton Press, 2002)
for practical ideas on using roses in the garden, and recommendations of
specific Floribundas which do well. Cox says that Floribundas are the
best of the Modern roses for most landscaping situations because of their
hardiness, free-flowering habit, bushy form, and flowering season. They
work well both as specimen plants and in combination with other flowers
and shrubs in beds and borders. Most grow 2-4 feet tall, and are dense
enough to be used as hedge plants. Varieties range from single,
semi-double, to double flowers. Some are fragrant. Specific varieties
mentioned by Cox are ‘Gruss an Aachen,’ ‘Iceberg,’ ‘Queen Elizabeth,’
‘Marmalade Skies,’ ‘Showbiz,’ ‘Betty Prior,’ ‘Escapade,’ ‘Nearly Wild,’
‘Lilac Charm,’ ‘Europeana,’ ‘Sunsprite,’ and ‘Apricot Nectar.’

findmyroses.com

This site will help you locate that rose, peonies and clematis you’re looking for. They have information for over 45,000 varieties and species, many with sources.