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Plant Answer Line Question

Keywords: Climbing plants, Rosa, Disease-resistant plants, Organic gardening

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 article from Oregon State University Extension lists resistant roses and their other qualities (scent, repeat bloom, color).

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.

Date 2017-05-10
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Plant Answer Line Question

Keywords: genetically modified seeds, Organic gardening, Seeds

I read an article recently that said some of my favorite seed companies are now owned by Monsanto. I don't want to use genetically modified seeds in my home garden, so I'd like to know where I can find more information on the sources seed companies use for the seed I am buying.


You may be referring to the January 2009 issue of the PCC Newsletter regarding Monsanto purchasing many of your favorite garden and farm seed catalogs. Territorial Seeds, Johnny's Seeds, Park Seed, Burpee, Cook's Garden, Spring Hill Nurseries, Flower of the Month Club, and Audubon Workshop are not owned by Monsanto or Seminis. PCC subsequently posted a retraction.

The folks at Organic Seed Alliance are a great resource on this issue. Here is what they suggest:
"For gardeners interested in buying non-GMO seeds, the best bet is to purchase seeds from seed companies who sell only organic seeds and who have signed the Safe Seed Pledge."

For further reading on the subject, see this February 2005 article by Matthew Dillon from the Rodale Institute on Monsanto's purchase of Seminis. Environmental News Network also has information about a September 2008 discussion forum with writer Michael Pollan and Monsanto CEO Hugh Grant.

Date 2017-12-08
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Plant Answer Line Question

Keywords: Organic gardening, Spiders

I'd like to help a friend start gardening organically. She is concerned about spiders in her garden, especially around her lawn. She would like to know of safe ways of getting rid of the spiders so her children will not be hurt by them.


Generally, spiders are not a problem with lawns, and are certainly not normally seen in large numbers at one time. They are considered beneficial in the garden, as they eat other insects. We do not often encounter dangerous spiders here in the Pacific Northwest. The following links may be useful in reassuring your friend.

  • Colorado State University Entomology
    "Spiders are beneficial inhabitants of any garden, ecosystem, or home because of their important contributions to biological control of pest insects. Spiders are considered to be the most important terrestrial predators, eating tons of pest insects or other small arthropods every year. Spiders are generalist predators that are willing to eat almost any insect they can catch. They are abundant and found in most habitats. They only need to be left alone!"
  • Burke Museum's Spider Myths by Rod Crawford
    "Myth: Spiders in the home are a danger to children and pets.
    Fact: House spiders prey on insects and other small creatures. They are not bloodsuckers, and have no reason to bite a human or any other animal too large for them to eat. In any interaction between spiders and larger creatures like humans, the spiders are almost always the ones to suffer. It is so rare for spiders to bite humans that in a 30-year career of handling tens of thousands of live spiders, I personally have been bitten twice. Both bites had only trivial effects.
    A person who is not an arachnologist would not likely be bitten more than once or twice in a lifetime. ('Mystery bites' which people thoughtlessly blame on spiders, don't count! There are no invisible spiders...).
    Very, very few spider species have venom that can harm humans, dogs, or cats. In most parts of the world, no spiders with medically significant venom have much chance of being found in houses. In the few areas that are an exception to this rule, the harmless house spider species still greatly outnumber the more toxic ones. And spiders whose venom happens to be more toxic to us, are no more likely to bite us on that account; they are unaware of our existence.
    Why, why do people waste their time worrying about spiders? It is not spiders that are dangerous to your children; the dangerous ones are other humans!"

For more general information on organic gardening and lawn care, see the following:

Date 2017-05-26
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Plant Answer Line Question

Keywords: Organic gardening, Sewage sludge, Compost contamination

I noticed at the Flower and Garden Show that King County Master Gardeners were giving away samples of biosolids for use in the garden. Is sewage sludge really safe? Is it acceptable if you garden organically?


The Environmental Protection Agency defines biosolids as treated sewage sludge. In January 2009, the EPA surveyed samples. Here is a brief summary of some of the findings:

  • The four anions were found in every sample.
  • 27 metals were found in virtually every sample, with one metal (antimony) found in no less than 72 samples.
  • Of the six semivolatile organics and polycyclic aromatic hydrocarbons, four were found in at least 72 samples, one was found in 63 samples, and one was found in 39 samples.
  • Of the 72 pharmaceuticals, three (i.e., cyprofloxacin, diphenhydramine, and triclocarban) were found in all 84 samples and nine were found in at least 80 of the samples. However, 15 pharmaceuticals were not found in any sample and 29 were found in fewer than three samples.
  • Of the 25 steroids and hormones, three steroids (i.e., campesterol, cholestanol, and coprostanol) were found in all 84 samples and six steroids were found in at least 80 of the samples. One hormone (i.e., 17a-ethynyl estradiol) was not found in any sample and five hormones were found in fewer than six samples.
  • All of the flame retardants except one (BDE-138) were essentially found in every sample; BDE-138 was found in 54 out of 84 samples.

Additional information is available from Cornell University's Waste Management Institute.

Here is King County's own information on biosolids recycling. Since the EPA is currently evaluating the results of their own survey, there may be revisions to previous notions that the concentration of toxins in biosolids was so low as to be inconsequential. In fact, the Center for Food Safety has petitioned the city of San Francisco to stop distributing biosolids at "compost giveaway events." Their website has additional information about potential risks associated with using sewage sludge.

In Washington State's Lincoln County, residents of a community that includes an organic farm fought to block a nearby mega-farm from applying sewage sludge to fields that would drain into Mill Canyon Watershed. While it is legal to use biosolids, there have not been enough studies of the effects on the environment to prove that it is safe.

The short answer is that there is uncertainty about the safety of using biosolids in the garden, and if you are attempting to garden organically, it may be best to avoid using them.

Date 2018-04-05
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Plant Answer Line Question

Keywords: Organic gardening, Mulching

While researching in the Library's periodicals yesterday, I read an article in Heirloom Gardener about getting tomatoes to ripen earlier. One of the steps was to put down a thick layer of newspapers, which would decompose and later be turned in to the soil. I am concerned about this being organic. However, the Internet sites I found were divided depending on the type of ink used. They made no mention of bleach or other chemicals used in production of the paper, but I wonder about that too. Finally, not many seemed very up to date.

Can you find better information?


There is a question like yours answered by George Weigel in PennLive.com, in which he suggests that it is probably relatively safe, given that many newspapers are now printed using soy-based inks. Here is an excerpt:
"That doesn't mean there still aren't people recommending against newsprint for various reasons (i.e. 'What about the waxes, pigments and other additives that might be in soy ink?' 'Aren't a majority of soybeans genetically modified, so doesn't that taint soy ink as a natural product?' And 'How do we know for sure that someone didn't slip something toxic into a batch of ink or that the newspaper temporarily switched to questionable ink because it found a bargain somewhere?')
"I guess you could argue that newsprint ink might not be 'safe' for those kinds of reasons, but then you could argue that just about anything in gardening poses a threat (what's in the water you're using, your fertilizer, fungicide-treated seeds, genetically modified corn varieties, pathogens in the compost, even the air you're breathing while putting down your newspaper mulch)."

Like you, I've wondered about newspapers as mulch, or as a shredded addition to the worm bin, too. One could not say that the papers and their inks are "organic," but most sources (like the one above) seem to say that the amount of toxicity that might still be present is small compared to other sources of toxins in our environment.

As far as use of newspaper in organic gardens, the Organic Materials Review Institute (which lists what is and is not allowed in certified-organic growing) covers this:

Newspaper is "allowed with restrictions" when used for pest, weed, or disease control, and is classified as a synthetic (not organic) control:
Class: Crop Pest, Weed, and Disease Control Origin: Synthetic Description: Glossy paper and colored inks are prohibited. Paper may only be used as a mulch or compost feedstock.
NOP Rule: 205.601(b)(2)(i) & 205.601(c) As herbicides, weed barriers, as applicable: Mulches. As compost feedstocks: Newspaper or other recycled paper, without glossy or colored inks.

I definitely recommend removing any colored newsprint and glossy inserts that come with the average daily paper. I personally wouldn't use newspaper mulch in a bed where food is being grown, but perhaps I am exceedingly cautious. You might want to be aware that nanotechnology is now being used in some printing inks, and in some glossy ads (such as Macy's) which are scent-microencapsulated (I found out about this because I complained to Seattle Times management about the odor). This link to Ink World magazine discusses the use of nanotechnology in printing. The environmental and human health implications of nanotechnology are still being studied.

Grist Magazine has also addressed the related issue of using newspaper in compost.

Date 2017-05-06
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Garden Tip

Keywords: Weed control, Organic gardening, Mulching, Herbicides

A common question we get at the Elisabeth C. Miller Library is How do I kill weeds without hand digging but without using toxic chemicals? Further discussion with the gardener reveals he wants to buy a product that he can spray on the weeds, once. Organic gardeners have it easier now compared to a decade ago, with a number of less-toxic weed killers on the market, but the fact is not one of these products is a magic bullet.

  • Corn Gluten Meal (Concern's Weed Prevention Plus and Whitney Farm's Weed Whompin Mulch) is a natural product that prevents seeds from rooting once sprouted. The downside is that it doesn't work during rainy weather. Another consideration is that recent studies show it acts as fertilizer because it is rich in nitrogen, so in garden beds it may actually increase weeds. Its best use would be for weeds in lawns, according to an article in Organic Gardening, Aug/Oct 2008.
  • Potassium salts of fatty acids (Safer Superfast Weed & Grass Killer) kills the tops of all plants, but not the roots. It works best on annual weeds like chick-weed and bitter cress, but would have to be repeated a few times to kill perennial weeds with root reserves, such as dandelion.
  • Pelargonic acid herbicide (Scythe) is another type of fatty acid, similar to soap, that kills weeds by drying out the leaves. As mentioned above this product works best on annual or biennial weeds and must be reapplied a few times to kill perennials.
  • Vinegar from the kitchen doesn't kill weeds, only disfigures them. Commercial products (Burnout, Bradfield's Horticultural 20% Vinegar) work if used in hot weather, but are quite caustic and great caution must be used not to inhale the fumes or spray the skin. Natural, yes, but toxic.
What does it take to get rid of weeds? A multi-pronged approach: physically remove weeds when they are young, reapply mulch every year, shade weeds out with desirable plants, and don't let weeds go to seed.

The Northwest Center for Alternatives to Pesticides publishes excellent articles on non-toxic pest control. Two good articles on weed management are available free online: Managing Weeds in Shrub and Flower Beds and Landscape Weed Control

Date: 2007-04-03
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Garden Tip

Keywords: Powdery mildew diseases, Organic gardening

Powdery mildew season has begun (May), so act now to prevent or slow the development of this disfiguring (though not usually lethal) disease. Research published in Crop Protection demonstrated good results for preventing and managing mildew by spraying once a week with a 20%-40% solution of non-fat milk diluted in water. The down side to this organic remedy is the white residue left behind by the milk, which resembles the mildew we're trying to cure in the first place! Other less-toxic sprays that are new to the market are:

  • Eco E-Rase (also sold as Detur), a jojoba oil spray that smothers mildew spores;
  • Citrall Organic Lawn and Garden Fungicide derived from Backhousia citriodora (Lemon Myrtle), native to Australia;
  • Rose Defense made with Neem oil, which is not so new, but is still unfamiliar to many gardeners.

Go online to Colorado State University for a fact sheet on powdery mildew.

Date: 2007-04-03
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Garden Tip

Keywords: Aphids, Organic gardening

Many plants outgrow aphid infestations with no harm done. But sometimes aphids do cause permanent damage to tender shoot of young plants. If action must be taken, soft-bodied aphids can be killed by common non-toxic ingredients found at home. Here is a recipe for a spray from The Frugal Gardener by Catriona Erler (Rodale, $27.95):

  • 1 garlic bulb
  • 1 small onion
  • 1 teaspoon cayenne pepper powder
  • 1 quart water
  • 1 tablespoon liquid dish soap
liquefy garlic and onion in a blender, then add cayenne and water. Steep for an hour. Strain the liquid through cheesecloth, then add soap. Spray directly on aphids, or on plants vulnerable to aphids, like roses. Keep away from eyes and skin. This spray may be kept refrigerated for one week.

Date: 2007-02-26
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Garden Tip

Keywords: Rubus discolor, Weed control, Organic gardening

Eradicating blackberry vines may seem hopeless, especially if you don't want to use chemicals, but don't give up just yet. The Northwest Center for Alternatives to Pesticides advises gardeners to cut off the top growth, dig out the main root-ball, and then follow-up by mowing all new growth. Planting desirable plants to shade out the sun loving blackberries is also critical. Read the NCAP's blackberry management plan (pdf).

Date: 2007-05-16
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Garden Tip

Keywords: Reference books, Organic gardening

The Rodale family of Emmaus, Pennsylvania has a 60 year history of publishing books and magazines that promote organic gardening and their encyclopedias have come to be regarded as the standards on the subject. A good example is the Rodale's Illustrated Encyclopedia of Organic Gardening (DK Publishing, 2002 $40.00). A must-have for serious organic gardeners certainly, but the user-friendly qualities that are a trademark of DK will make it one of the first books in a beginning gardener's library as well.

Date: 2007-07-12
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Garden Tip

Keywords: Organic gardening

Ever wonder what you can do to combat global warming? The Union of Concerned Scientists has produced a guide called "The Climate-Friendly Gardener: A Guide to Combating Global Warming from the Ground Up." The gardening choices we make can maximize carbon storage and minimize pollution. This publication discusses fertilizers, cover crops, food gardens, composting, lawn maintenance, and more. You can also sign a pledge to be a climate-friendly gardener!

Date: 2010-05-05
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May 22 2018 15:48:30