Author: Linda Chalker-Scott

Dr. Linda Chalker-Scott has a Ph.D. in Horticulture from Oregon State University and is an ISA certified arborist and an ASCA consulting arborist. She is WSU’s Extension Urban Horticulturist and a Professor in the Department of Horticulture, and holds two affiliate associate professor positions at University of Washington. She conducts research in applied plant and soil sciences, publishing the results in scientific articles and university Extension fact sheets. Linda also is the award-winning author of five books: the horticultural myth-busting The Informed Gardener (2008) and The Informed Gardener Blooms Again (2010) from the University of Washington Press and Sustainable Landscapes and Gardens: Good Science – Practical Application (2009) from GFG Publishing, Inc., and How Plants Work: The Science Behind the Amazing Things Plants Do from Timber Press (2015). Her latest effort is an update of Art Kruckeberg’s Gardening with Native Plants of the Pacific Northwest from UW Press (2019). In 2018 Linda was featured in a video series – The Science of Gardening – produced by The Great Courses. She also is one of the Garden Professors – a group of academic colleagues who educate and entertain through their blog and Facebook pages. Linda’s contribution to gardeners was recognized in 2017 by the Association for Garden Communicators as the first recipient of their Cynthia Westcott Scientific Writing Award. "The Garden Professors" Facebook page - www.facebook.com/TheGardenProfessors "The Garden Professors" Facebook group - www.facebook.com/groups/GardenProfessors Books: http://www.sustainablelandscapesandgardens.com

Surviving the desert with beauty and efficiency

I’m away this week for an out-of-state seminar and a little annual leave.   Some of my favorite places to visit this time of year are the high deserts of California.  Today we hiked to Horse Thief Creek, a relatively easy trail in the Santa Rosa Wilderness.  It’s the perfect time of year to see the high desert in bloom, especially with last winter’s substantial rainfall.

In graduate school I became interested in environmental stress physiology, and I still am entranced by the plant kingdom’s ability to overcome nearly every environmental extreme on earth.  Desert ecosystems are particularly harsh, as rainfall is limited to a short period of time, often in the winter or spring.  While many perennials are able to tolerate the subsequent dry season, annual species cannot.  In essence, they escape drought stress altogether by existing only in seed form for most of the year.  Seeds contain relatively little water anyway, and are so protected against environmental extremes that they can remain viable for decades or even centuries.

But back to our desert.  After the rainy season, seeds of annual plants go into overdrive, germinating, growing, setting seed, and dying back all the span of a few weeks.  Thus, the lucky hiker can find an abundance of tiny, brilliant desert annuals when seasons and vacation schedules coincide.

Tomorrow it’s the Salton Sea.  Not sure what we’ll see in terms of plant life, but we’re hoping to catch some of the migratory waterfowl on their journey north.

 

 

 

 

Friday investigation – April Fools!

I didn’t exactly cheat on this one…but it was a mean trick nevertheless.

This is a contorted cultivar of Larix (can’t remember the exact name and I’m out of town this week), hence the twisty needles.  And indeed the tree is senescing.  The newer growth (the second flush of the season) just wasn’t as prepared for fall as the older growth, which is yellowing naturally.  So everything is just peachy with this tree.

Just goes to show you how important it is to know all the details when doing distance diagnosis!

 

Building healthy soils?

I love living in Seattle…but I’m getting increasingly impatient with the City’s “Building Healthy Soils” propaganda.  For years I’ve questioned their recommendation to perpetually amend landscape soil with organic material to no avail.  Let’s see what you all think of their “fact sheet” (which you can read here in its entirety).

“The best way to improve the soil is to add plenty of compost or other organic matter throughout the entire planting area before planting. Thoroughly mixing these materials deep into the soil helps provide water, air and nutrients to plant roots.”

Hmm.  No mention of how to determine IF your soil needs improving; without a soil test, you have no idea what your baseline organic matter level is.

But perhaps this recommendation is only for vegetable gardens and annual beds?  Nope.  In the next paragraph, we’re told to “Mix in organic material before planting lawns, perennials, trees and shrubs.”  We’re given helpful how-to instructions:  “Use a shovel or digging fork to mix amendments into the top 6 to 12 inches of soil. It is important to amend the entire planting bed — not just small holes for each plant. When planting individual trees and shrubs in lawns or existing beds, amend an area at least 3 feet wide, or 3 to 5 times as wide as root balls over 12 inches in diameter. Rototill large areas where digging is impractical.”

Now we’ve got a serious problem.  This practice is recommended for existing beds.  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).

But let’s continue to ignore reality and go on to the annual recommendations for adding compost to soils.
“Clay soils: 16 cu. feet (.6 cu. yard) = 2 inch layer of compost for new gardens. Use 1 inch per year in established gardens.”
“Sandy soils: 24 cu. feet (.9 cu. yard) = 3 inch layer of compost for new gardens. Use 1 – 2 inches per year in established gardens.”

Is the compost used as a mulch in these existing gardens?  No – the guidelines are prefaced with this instruction:  “Gardens: mix compost to 10- to 12-inch depth.”  (Can’t say this does much for promoting root growth either.)

This document shows a breathtaking lack of understanding of how landscapes function, especially over the long term.  It takes an agricultural practice (annual organic amendment of crop fields) and misapplies it to permanent landscapes.  It is devoid of the research which continues to show that 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.

Devious dandelions

As Austrian reader Johannes explained, the difference in dandelion flower height is due to herbivory – in this case from a lawnmower.  Dandelions are quite adaptable to variable environments (the phenotypic plasticity Johannes also mentioned) and flower heights will increase or decrease depending on these variables. This ensures that the flowers will be accessible to pollinators, yet not decapitated by lawnmowers.  It’s just one of the fascinating traits that make weeds successful!

 

A Taraxacum teaser

It’s spring and the dandelions are happy to see you!  I’ve taken photos of two groups of dandelions just footsteps away from one another. The populations are both in full sun, with similar types of soil and water availability. You’ll note that one group has very short flower stalks, while the second has longer stalks:

So what’s responsible for the difference in flower stalk length?  And for extra credit, what’s the scientific term for the phenomenon?

If this isn’t something you’ve noticed before, you will from now on!  Answers Monday!

Organic or local?

I grew up on a small farm (30 or so acres) near Tacoma, Washington. We raised our own Herefords, I gathered eggs from my frizzle chickens, and we all enjoyed apples, plums and cherries from our fruit trees.  Neither of my parents were farmers by profession, though my grandfather owned a dairy farm in Oregon.  Eventually, my husband and I hope to move back to the family farm, if for no other reason than preserve it from the surrounding encroachment of houses.

I’ve been thinking about things I might do for fun or profit on the farm.  Home grown beef for sure.  A veggie garden – finally – on some of the only native soil left in the area.  We’ve got lots of options and the space to try them out.

Now back to the question in the title: organic or local?  Our family property has been managed gently since we moved there in the late 1960’s.  Nothing’s been added to the pasture soil other than what the animals deposited themselves.  We’ve had the apple trees sprayed yearly (a requirement because of apple maggot), but this is a targeted application with little affect outside the trees.  The cattle were never treated with hormones or other additives – they were about as free range as you can get.

I’ve heard from others that organic certification standards have become increasingly difficult to meet and some growers think they have become increasingly meaningless.  On the other hand, locally-grown products are becoming more available.

Is it time for a new standard – locally grown, with some requirements (e.g. soil tests) to demonstrate safety?

Friday puzzle revealed

And we have a winner!  As Karen guessed, these are lichens on decomposing granite:

This photo is from the Fortynine Palms oasis area in Joshua Tree National Monument.  These lichens (symbiotic amalgams of fungi and algae) could be decades or centuries old – they are very slow spreading. 

Most creative answer goes to TT, who thought it looked like sweet potato casserole!  The quartz does look like marshmallows.

Another fine product…

I’m spending this week in Palm Desert, CA for a little R&R in the sun.  In the morning, with my pot o’ Earl Grey, I read the local paper (The Desert Sun).  Last Sunday’s paper provided me with an article about an “intelligent water incubator” (all material in quotes was taken from the article).  Pieter Hoff, a “Dutch scientist, author, and major exporter of lilies and flower bulbs” has invented the Waterboxx, which “produces and captures water from the air through condensation and rain.”  He claims a four year test in the Moroccan Saharan desert showed an 88% survival rate for fruit tree saplings “grown without irrigation.” He now wants to test his invention in the Coachella Valley desert “to create a money-making business model with trees” and of course to help save the environment.

The Waterboxx is a plastic rectangular box, but we’re told the inner technology is more complex.  The box is put around the seed or sapling and provides water “in small doses.”  It also “protects roots against sun, wind, weeds, rodents and some animals.”

I visited the web page and you should too.  The technology section is fascinating.  It includes an animation explaining how the box functions; apparently the box was designed to protect seeds in the same manner as bird poop.  I was interested to see that the box requires 4 gallons of water when it’s set up; not exactly a “no irrigation” methodology.  And that a wick inside the box releases about 50 ml of water a day to the soil below the box.  The last frame tells us “with the waterboxx we can transform most of the deserts into forests.”

I won’t test your patience by dissecting all the silliness in this article and the web site.  As you might expect, there is no peer-reviewed science on this product, nor even a research report.  The plant and soil science is marginal; the ecological science is horrific.  The box effectively prevents water from reaching the soil around the seedling, doling it out in miniscule doses instead.  Not only could a decent organic mulch layer do the same job (and do it better), but I question the “greenness” of creating yet another plastic product with a limited lifespan.   This system is so removed from reality that it’s incredible that anyone takes it seriously – yet it’s been out there for several years now and has won several awards.

Oddly, there’s little specific information about the inventor.   All I could find definitively is that he comes from a bulb-raising family in The Netherlands and has written a book:  CO2 – a gift from heaven (under the name Petrus Hoff).