By Cynthia Lee Riskin
Master of Environmental Horticulture
Seattleites now have a kind of free dating site for arborists and gardeners. Portland businessman Bryan Kappa recently opened a Seattle branch of Chip Drop (http://www.chipdrop.in/), which connects arborists to homeowners who want free woodchip mulch. Homeowners put their addresses on a map, and arborists working nearby can drop their chips in any yard on the map. Founded only six months ago, Chip Drop doesn’t yet charge for the service, which is in 19 cities and is growing rapidly.
The Chip Drop model works well for Joe Bryant, at Washington Tree Experts, in Pinehurst. He says the company doesn’t charge for arborist chips or wood because they love helping their neighbors and it helps the company out, too. (Drive past 11307 15th Ave. NE to see if there’s any free woody material for grabs.)
Wood chips are “superior” for enhancing plant productivity, writes Linda Chalker-Scott in the now-defunct Master Gardener magazine. The PhD plant physiologist with WSU extension—who has professorial duties at both WSU and UW and has published books on garden sustainability and gardening myths—cites many benefits of mulching with arborist chips. It:
- Reduces weeds
- Directly adds nutrients
- Increases the diversity and activity of soil organisms, which help convert soil nutrients into plant-usable forms
- Absorbs and retains moisture, reducing watering demands and storm water runoff
- Neutralizes pollutants
- Prevents soil erosion and compaction
- Decreases pests and pathogens while supporting beneficial organisms
- Moderates soil temperature extremes
- Looks good
Best of all, these chips are free. Many pricey mulches, such as bark and sawdust, actually cause problems for plants. Bark naturally has a waxy coating that repels water and creates a fire hazard. It is likely to introduce weed seeds (think horsetail), and because it is sometimes stored in saltwater, can emit toxic levels of salt into the soil. Sawdust is so fine that it is impenetrable to water.
On the flip side, Dr. Chalker-Scott says many of the ills ascribed to wood chip mulch are false. She says most studies show that woodchip mulch:
- Deposits rather than robs the soil of nitrogen
- Doesn’t transfer pests or diseases to plants even if the chips come from diseased trees
- Does not emit chemicals that prevent other plants from growing, a process called “allelopathy.” (Black walnut (Juglans nigra) is an exception, but Western redcedar and arborvitae (Thuja spp.) are OK.)
Of course, there’s a catch: Homeowners won’t know whether or when arborists will drop off chips and should expect 5 to 12 cubic yards. Twelve cubic yards is enough to cover 1,000 square feet with nearly 4 inches of mulch. Kappa suggests recipients share their bounty with neighbors through such forums as Craigslist, Facebook’s “Buy Nothing” pages, or a classic “Free mulch” sign stuck in the pile.
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Tip: To figure out how many cubic yards of wood chips you can use in your yard, check out Web sites such as the Landscape Calculator, or consult a 7th-grader, who knows that volume = length x width x depth.
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Another caveat is that you won’t know what you’re getting until you have way too much of it. Dull chipper blades make coarse or uneven chips, says Shoreline arborist Chuck Hinshaw, who owns 2nd Nature Arborist Services, Inc. If the arborist’s crew happens to be pulling ivy that day, you might be inheriting that, too. Seattle plant expert and arborist Arthur Lee Jacobson notes that the quality of the chips can make a huge difference in growing outcomes.
Ultimately, though, Chip Drop can help close the sustainability loop. With many more options for where to drop chips, arborists can save the time and costs of driving gasaholic dumptrucks to distant composting sites and paying to unload. Homeowners are more likely to get a free pile of mulch—and meet their mulch-minded neighbors when they share the pile.
Arborists and Gardeners can register for Chip Drop at http://www.chipdrop.in.
For more information on wood chip mulch from Linda Chalker-Scott, see:
You can get hold of arborist Chuck Hinshaw at 206 365-2442. Arborist and plant expert Arthur Lee Jacobson is accessible through http://www.arthurleej.com/ or (206) 328-8733. To contact Washington Tree Experts, go to http://www.washingtontreeexperts.net/ or call (206) 362-3380.
Disclosures: Note that as far as I know, everything in this brief article is objectively true, but it does not qualify as classic, ostensibly unbiased journalism.
After I wrote the bulk of this story, Washington Tree Experts dropped off a lovely load of arborist chips at my house. Arthur Lee Jacobson and Chuck Hinshaw are friends. Linda Chalker-Scott is my colleague and former school advisor. All photos are shamelessly swiped from http://www.chipdrop.in/.
