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

A Garden Professor migrates east, albeit briefly

I was AWOL last week, as I had 3 presentations to get ready for 3 different states all in the span of 4 days.  Yow!  But they are over and done, and I’ll try to keep up on the blog from now on.

This is a short but amusing post (to me anyway).  My second talk was in Virginia, where I spoke to Master Gardeners at their annual conference.  The speaker right before my talk was fellow GP Holly Scoggins.  (Note to self: never agree to follow Dr. Scoggins again.  I’m not nearly as amusing, though I am almost as tall.)

Anyway, Holly was discussing garden trends among other things and mentioned meta-gardens.  Hmmm.  I hadn’t heard of these, but assumed that, like meta-analyses, they were probably gardens that showcased plant collections from other places.  Kind of like arboreta but smaller, and maybe something you could do at home.  I nodded wisely, pretending that I was fully on board with this new trend.

Alas.  My west coast ears were not adapted to Holly’s southern accent.  As I discovered several slides later when it was obvious she was talking about meadow gardens.

Oh well.

Gigantic hostas

I know Friday’s puzzle was a bit too easy – but I needed some way to discuss the giant hostas we have in our landscape this year:

We have had a very wet and cold spring.  While it was misery for us above-ground types, the plants absolutely loved the abundant water.  When the leaves open and expand on these continually-watered plants, they reach maximum size.  The hosta leaves in this photo aren’t the size of dinner plates – they’re more like turkey platters.

A word of caution to all of you with similar happy plants:  when the drier, hotter months of summer arrive, you’re going to have to keep these puppies well watered.  Otherwise, the leaves will soon turn crispy and brown around the edges.

WOW again (Why oh Why?)

I’m going along with the “dead tree” theme of the week, but doing a little prognosticating at the same time.  Bert and Holly showed you tree demise on site; I’m going to show you tree demise in the making.  We can call this “dead plant walking.”

I’ve done a few WOW postings in the past, often with a focus at what you might find at a nursery or big box store.  Here’s a recent find at an unnamed BBS, in the “topiary” section:

Unless you intend to have a giant stake as part of your topiary statement, this tree (actually a juniper) will morph into a prostrate form before your very eyes. Fortunately, it probably won’t live long once transplanted since it’s so overdue for potting up that the pot has split:

You can just imagine the nest of woody roots fusing into a functionless mass, can’t you?

Run, don’t walk, away from nursery plants like this.  You’ll be glad you did.

A jewel of an orchid

Orchid fanciers Derek and Joseph correctly identified Friday’s mystery plant as a jewel orchid, specifically Macodes petola:


Friday’s sparkly leaf photo shows why “jewel orchid” is the common name used for several genera of orchids with showstopping foliage.

And Ray noted that Goodyera spp. (rattlesnake plantain) is a native US jewel orchid with beautiful variegated foliage. Next time you’re hiking in the woods, keep your eye out for this common yet striking plant.

Does colored glass help root cuttings?

I get a lot of questions about a lot of different products and practices.  New topics send me to the scientific data bases and that’s where I went for today’s posting.  One of my garden writing colleagues asked me about colored glass rooters – glass containers in different colors that can be filled with water and a plant cutting.  The conventional internet wisdom, according to my colleague, is that green and blue glass rooters are the best.

The first mention I could find of such a practice is from an 1801 publication called The Cottage Gardener.  In it, we’re informed that for rooting cuttings “such coloured glass is useless; it has no influence over the production of roots.” Nevertheless, 200 years later web postings like “I have found that cuttings placed in colored blue or green glass root faster than clear glass” are taken as solid evidence that blue or green glass containers are best for rooting cuttings.

There is science behind different colors of light and rooting, but it’s a little more complicated.  Chlorophyll absorbs red and blue light best, so plants whose leaves are exposed to red and blue light grow well and tend to produce a healthy flush of roots.  On the other hand, plants whose roots are exposed to blue light have decreased root growth compared to those under white light conditions.  In this case, the photoreceptor called cryptochrome might be responsible for inhibition, as it is a blue light absorber.  Similarly, plant roots exposed to green light do not grow as well as those exposed to white light.

In my opinion, this is another example of aesthetics trumping science.  Of course colored glass rooters are more attractive that plain old glass jars.  And that’s a perfectly valid reason to use them as part of one’s home decor.  But it’s not science, nor is it necessarily the best way to encourage rooting.

What seems to be most important in rooting cuttings in water is to use indirect lighting (north-facing windows in the northern hemisphere, for example) so that the water doesn’t get too hot.  And keep in mind that not all species root well from cuttings.

Mystery pits revealed

I’d turned Friday’s picture on end to try to fool you…but to no avail.  Deirdre and Gail both guessed woodpeckers, and yes, this is sapsucker damage:

Though some woodpeckers look for insects under the bark, sapsuckers drill neat lines of wells that fill with sap.  The birds can then move down the line of wells, lapping up sugar water.  (Kind of the avian version of lining up tequilla shots on the bar.)  Healthy trees are generally not at risk of dying from drilling injury, though if the tree is completely girdled that would be a problem.  Trees stressed by other factors could be also be killed by this final straw.

(Deb and @s both thought the photo might be a cactus skeleton, and it certainly looks like one!  Hadn’t thought of that myself.)