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Elisabeth C. Miller Library

Keyword: Mulching

information sources about mulching

Can you give me some good sources for information about mulching and different mulching materials?

Below are many links to information about mulch, including several from Pacific Northwest government agencies. Explore these sites for lots of other useful information about gardening! There are also many helpful books on the subject, such as Mulch It! by Stu Campbell (Storey Books, 2001) and the Brooklyn Botanic Garden’s guide, Healthy Soils for Sustainable Gardens edited by Niall Dunne (2009).

There is an excellent introductory article on the Brooklyn Botanical Garden website entitled “How to Use Mulch”.

ABOUT MULCH, types, and uses–Cornell Cooperative Extension (NY)

King County (Washington) Solid Waste Division mulch info
Make the mulch of it!

INFORMATION FROM THE PACIFIC NORTHWEST (generally useful)
—
Saving Water Partnership (Seattle)

—King Conservation District (Washington), manure share program

COMPOSTING COUNCIL OF CANADA:
Compost.org

Pine needles as mulch

Are pine needles good for mulch in the garden and for fruit trees?

Pine needles are most often used with plants that prefer acid soil, but according to Mulch It! by Stu Campbell (Storey, 2001), they can be used elsewhere, too, at a depth of one to one and a half inches. It is considered a myth (see information from Washington State University horticulture professor Linda Chalker-Scott in Organic Gardening, February 2007, p.8) that they will acidify your soil. They are good for insulation, weed control, and moisture retention, and excellent for water penetration. However, they decompose very slowly and are not liked by earthworms. You can shred the needles a bit before applying them as mulch, and that will speed their decomposition.

on the use of wine corks as garden mulch

I attended a garden lecture where the speaker recommended using wine corks in the garden, either ground up as a mulch, or whole in containers. She said cork would help with moisture retention in the soil. Do you agree?

 

The primary source of wine corks is the cork oak tree, Quercus suber. The species name is a clue to the fact that cork is largely made of suberin, a waxy hydrophobic (water-repelling) substance found in other woody plants.

It does not make sense to use a hydrophobic substance as a mulch, since mulch is meant to allow moisture to reach the roots of your plants, not to repel water. For the same reason, it does not make sense to add cork to your containers, either. Professor Linda Chalker-Scott of Washington State University says that cork will not in any way help the soil retain water.

Chalker-Scott has long advocated using arborists’ wood chips as a mulch rather than bark mulch, for similar reasons:
“Bark does not function like wood chips in its water holding capacity. Bark is the outer covering of the tree and is heavily suberized to prevent water loss. Suberin is a waxy substance that will repel water, and in fact helps explain why fresh bark mulch always seems dry. Wood chips, on the other hand, consist primarily of the inner wood, which is not suberized and has the capacity to absorb and hold moisture.”

applying compost versus adding fertilizers to gardens

I have a large and never-fed garden. I wish to start feeding these plants. I’m composting now, but when and how often do I fertilize?

 

Has your garden been thriving in years past? If so, I don’t think you need to add fertilizers. There’s no single packaged fertilizer that will be universally beneficial to every plant in your garden. Different plants have different needs, and it’s never wise to add fertilizer without doing a soil test.

On the other hand, you mention you are tending a compost pile. You can apply compost once or twice a year and it will be helpful to all your plants.

Here is information from The Ann Lovejoy Handbook of Northwest Gardening (Sasquatch Press, 2007):
“When do we need to feed? For ornamental plants, including trees and shrubs, spring and fall are the traditional feeding times. Spring feeds are generally fast-acting, offering rapidly growing plants the nutrients they need for a strong summer performance. A feeding mulch of compost can be fortified with fast-acting alfalfa, which will release more nitrogen if combined with composted manures. Alfalfa comes in meal or pellets. I like the big pellets used to feed goats, which are easy to spread and are available without added medication [my note: some alfalfa is treated, for use as animal feed].

“In fall, most plants stop producing fresh top growth, even though our Northwest winters are generally mild. Fall is a good time to feed roots, which continue to stretch and grow underground despite low temperatures. Adding whole fish meal to your compost feeding mulch will fortify roots with phosphorus.”

Professor Sarah Reichard, director of UW Botanic Gardens, discusses fertilizers as sources of pollution in our water supply. In her book The Conscientious Gardener: Cultivating a Garden Ethic (University of California Press, 2011), she states:
“If water inevitably drains downhill, how do we stop fertilizers and pesticides from moving with it? The easiest way is not to use them. This needn’t come at the cost of your plants. Most woody plants and herbaceous perennials do not require much fertilizer. Mulching with well-aged manure, compost, or other easily broken-down organic materials will supply all the necessary nutrients.”

conditioning clay and heavy soils

Help! My clay soil is stunting the growth of my plants. I’ve amended the soil with compost and manure. Is there a another method of conditioning the soil that you can recommend?

 

First and most important, it appears mulching is the best organic solution for conditioning clay and heavy soils. Organic soil conditioners include compost, well-rotted animal manures, and natural fertilizers. Planting green manures such as clover, rye grass, or vetch are also effective for breaking up large clods in clay soil over time.

Sheet composting – laying compost over the entire area to be worked and using a fork (or rototiller) to work it into the soil to a depth of 2-4 inches – is cited by the resources listed below as an efficient method of soil conditioning. Both books listed below recommend repeating this process at least twice a year, in early spring and in late fall.

Secrets to Great Soil [by Elizabeth P. Stell, 1998, (pbk)] and

The Gardener’s Guide to Better Soil [by Gene Logsdon, 1975, (pbk)]

The Saving Water Partnership (the City of Seattle and other government entities) has a website full of information about improving soil.

The site includes Growing Healthy Soil.

Current thinking contradicts the notion of working compost or other amendments into the soil, as explained in a March 31, 2010 Garden Professors blog post by Professor Linda Chalker-Scott of Washington State University Extension Horticulture. She specifically takes issue with the “Growing Healthy Soil” information linked above. Here is an excerpt:
“Not only will extensive digging or rototilling destroy any soil structure you might have, it will also take out the roots of any desirable plants in the vicinity). […] improper soil amendment can cause serious problems such as soil subsidence, perched water tables, and nutrient overloads. This last point is especially important to anyone living near aquatic ecosystems, since excess nutrients always end up in the water.
Before you plant this year, find out what your soil needs before amending it. And remember that mulching is the natural (and sustainable) way to add organic matter to the soil.”

on use of newspaper in organic gardens

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. Harvard’s School of Public Health explores the environmental and human health implications of nanotechnology in printing.

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

usage of sawdust as mulch

We recently had a large blue spruce tree cut down and had the stump ground. Would the resulting sawdust be a good mulch for roses?

Also, what is your opinion of using a pre-emergent herbicide for weed
control in our rose bed?

 

Sawdust has high carbon content and may rob soil of nitrogen and moisture. It is also recommended for acid-loving plants and may be problematic for roses. There may also be compaction problems with sawdust, so it may need to be combined with other mulching materials to improve water penetration. Sawdust also decomposes slowly and compacts (Source: Mulch It! by Stu Campbell, Storey Communications Inc., 2001).

You may also be interested in two articles by Linda Chalker-Scott. In Wood chip mulch: Landscape boon or bane, she discusses the pros and cons of wood chip mulch. She also comments on sawdust in an article called The Myth of Pretty Mulch.

If you had spruce chips, they would be fine for mulching roses. Avoid
letting mulch touch the main stem; the goal is to pile it on the root
system away from the stem. You can remove it in the spring, or at least
be sure that it’s not too deep. While mulch protects from cold in the
winter and drought in the summer, if it’s too deep, water cannot get to
the root zone of the plant.

I would recommend that you avoid chemicals, as I find that you have to pay more attention when you use them than if you just wander through the garden now and then and pull all the weeds you see.

Pre-emergent weed controls never provide complete weed control. The most important thing to do is weed the area first, as pre-emergents only control weeds that have NOT sprouted. And if you have lots of seeds in the soil, don’t expect weed killer to eliminate them all. If water is required, beware of too much water (i.e., rain) that can wash away the herbicide.

Rather than use a chemical, I would weed the area now and then apply mulch. In addition to protecting the roots and soil, the mulch will suppress weeds, possibly until spring. You will have to watch for weeds that do sprout and be sure that you don’t let them go to seed. Otherwise, you will set yourself up for lots of future weeding. Chemicals don’t really help in situations like that, as you have to time their application perfectly. Hand weeding and mulching–well timed–can work better than any herbicide.

Garden Tip #14

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