While climate change is most apparently signaled by heat waves, melting glaciers and super-storms, plants go largely unnoticed as an indicator – until their burning causes mass destruction and evacuation.

Admittedly, plants have a subtle way of speaking to us. But to the trained eye, Seattle’s gardens and landscapes have been signaling changes in the climate for decades.

Enter Glenn Withey and Charles Price, owners of Withey Price Landscape and Design and two of the Pacific Northwest’s sharpest horticultural minds. Glenn and Charles have been gardening together for more than 30 years, during which time they’ve become incredibly in tune with the region’s plants and climate. If anyone can translate what our gardens are trying to tell us, they can.

In the spirit of fair warning, Glenn and Charles take a brutally honest approach to horticulture, which is reflected by some “colorful” language in the forthcoming responses.

I wouldn’t have it any other way.

Is climate change noticeable in Seattle landscapes and gardens. If so, how?

Glenn Withey: The weather is drier for much longer stretches than it used to be (when we were children in the 1960’s into the 70’s).  Much more drought stress is visible on native plants.

Heavier rainfall at times, again compared to our youth when it would drizzle for days on end, but no “gully washers”…

Charles Price: We did have ‘gully washers.’ They were very infrequent; usually November systems, plowing around in the ambient drizzle would give us a few super showers, swelling steams, flooding rivers. Our summer thunder storms never seemed to produce the precipitation levels we now seem to get at least a few times a year.  There were occasional dramatic hail storms, but not the things which plague other parts of the continent, with cow killer softball sized stones. The ‘sky’ looks taller than it used to around here, more frequently, it’s increase in lockstep with the number of the super showers.

What was the first warning sign for you? When did you notice it?

GW: Kind of hard to say “when” as the two of us were talking about climate change back in the 1980’s. Not really a new topic, more the case of the public willfully ignoring it.

For a warning sign? I would say the increasingly long periods of little to no rain, during our growing season. Kind of very gradually crept up on us, along with brief, but intense heat spells in May, which we never had growing up.  

I would say that things became more obvious starting in the early to mid 2000’s…. We loved planting Rodgersia ‘Rotlaub’ and other dark leafed forms. They never ever used to burn/crisp/deform, when pushing out new growth.

But, when we lived at the Dunn Gardens, we started getting heat waves every May (it seemed) that would indeed damage the foliage.  It got to a point where we stopped using plants like this, as why have a deformed looking plant for the entire growing season?

CP: I’d add that larger leafed rhododendrons were also increasingly affected by the hot flashes, who’s seemingly low humidity (I have not looked at historic overall humidity levels for May/June), precluded the plants keeping turgor, let alone keeping up with the accelerating expansion of the leaves, they would show a constriction, even tissue damage. Burn marks on juvenile and young adult leaves, crispy infant emerging foliage, and then the constrictions noted above, making themselves known for the following months.

Which plants and gardening techniques are at risk? Which ones are more viable now than in the past?

GW: Gardening techniques or plants? Well, we did the “English Border” look early on in our career. Plants need/want an even amount of moisture throughout the growing season. That is less appealing to the public as the cost for water has skyrocketed…

Many rhododendrons resent the dry summers, and are under increasing stress/failing. Ditto azaleas and many plants that have been the “backbone plants” that one sees in older gardens in the region.

This also ties into not having enough summertime heat to fully “cure” or “ripen” the wood on plants that are borderline hardy.  Without the heat, these plants go into the winter months tender and more susceptible to cold damage. So, even though our summers are getting warmer, it still isn’t enough with our maritime influence, to have many of these borderline plants work successfully in gardens – especially the further one goes inland from the Sound.

Again, hard to say as the climate is only getting wackier as far as what is more viable. With the potential for winter cold, many drought tolerant plants can’t take being zapped by a sudden cold snap. With the jet stream being ever more “flexible,” there is an greater chance of getting cold snaps that will fry the drought tolerant, but not fully cold hardy plants.

 CP: Hmm.. Rather big questions.

As an example, there were some Arbutus x andrachnoides ‘Marina’ in the city in the late ’80’s. I’ve read it was newly ‘released’ (made more generally available) from the Saratoga Horticultural Foundation, but very few of them made it through the early ’90’s. Those were the last winters like childhood winters in the late ’60’s. Then ’87 to ’92 wiped out a bunch of experiments. Star jasmine only survived, to my knowledge, in the warmest parts of the city and mid Puget Sound basin. Most ‘Marina’s were reduced to coming back from the crown, as it would in it’s fire system adapted habitats.

‘Marina’ seems to have had a pretty good run the last couple of decades, other than ice and snow mechanical damage, and bud’s nipped by frost.

Our native Hemlock isn’t very happy looking. More adelgids on more trees. Droopy, thin looking trees scattered far apart in the city. Traveling about the city, including into parks, I don’t see many of the so beautifully appointed young trees they make, with their delicate lilting tips. They aren’t apparently germinating with as much success as they used to.

Then there’s Acer macrophylum (Big Leaf Maple). I think we’re in the second act of a grim playout. There were a number of heavy Verticillium wilt years, which led almost directly to the increasingly reduced general size of the leaves produced yearly, to crown ‘thinning’, and now, the loving attentions of a ‘new’ caterpillar species, which had swaths of the trees looking as though they had been hard put to hail and buckshot. It’s interesting what you see looking directly at the top of a tree from a bridge.

It seems the answer to many local environmental problems is increasing the native flora. Is it possible to “wow” the neighbors with a fully native garden?

GW: While we like plant natives, we don’t see the reason for going “native only.” The pollinators don’t seem to care if a plant is native, or not, as long as there is nectar/pollen. Many of our native plants have a short flowering cycle, and are truly happy in a forest setting.

The urban/suburban environment is the exact opposite of a forest setting, so many people set themselves up for failure by not taking this into account – when wanting to plant with PNW natives. We are pragmatic, and too many “natives only” gardeners are way too dogmatic for our taste…

CP: People who go about making shade, increasing humidity – often by curtailing airflow – will be able, with only an occasional irrigation, or not, be able to grow a decent looking entirely ‘native’ plant garden. Trial and error is the gardener’s friend.

Shady spaces like this woodland walk are preferred by most PNW native plants, but hard to come by in residential and commercial areas. Photo courtesy of Withey Price Landscaping.

Shade (unless very bright), high humidity, low air flow, are the opposite of what we do when practicing commercial and industrial horticulture. Stagnant air/humidity will increase the incidence of foliar disease. 

Most of the annual plants commonly grown for ‘color,’ and many of the popular perennials, flowering shrubs and trees, are either from native climes or laboratory climates which provide long periods of stable temperature and moisture levels.

I rarely see Banana slugs in the city anymore. The air doesn’t seem to feed the simple colonial growths on stone, bark, and foliar surfaces as it used to. I believe that fungal/algal slime is what they cherish.

There are numerous ornamentals which give enough of themselves to merit inclusion in our gardens, some of which are adapted to our climate and don’t require irrigation when properly sited.  They are the plants which we must also be most vigilant towards, as the ones most likely to succeed in the wild, left to their own devises.

For many generalist pollinators, we can increase the time span available with sufficient food, by having a range of plants which provide nectar and pollen continuously through the majority of the year, to enable multiple generations of insects to develop, which is often, but not always, to our benefit. We’ve been looking at research by the Xerces Society and others on native/exotic plant, pollinator, and crop interactions, and the recommendations coming out of that research. 

Also, our anecdotal observations of insect preferences in nursery rows, gardens, and the greater/wild environment shows that there are lots of readily available ways to provide benefit through our gardens and landscapes, and modify our ‘unnatural’ impact so it’s an increase in life for a lot more of the native, local life.

It usually involves non-toxic water being available and used in some quantity, in some way, through the summer months. Bird baths, annual flower color (single, not fully double flowers, which often lack reliable nectaries or nutritious pollen), recirculating streams and waterfalls of filtered water, not treated with persistent toxic chemicals. Regular irrigation, either frequent or not, depending on the needs of the planting, will at least provide a source for drinking and bathing to numerous creatures.

Which wasteful landscaping practices drive you nuts?

GW: Fucking leaf blowers and endless string line trimmers/idiot maintenance people who don’t know what the fuck they are doing. Let’s cut off all of the flower buds, so we can shape the plant into a cube/meat loaf shape.

Get the idea?

That, and people who are too lazy to water a dying tree that they walk past, day in/day out. Why not move to a condo? If you are going to be homeowner, how about offering some sustenance to our pollinators and some visual relief for the neighbors?

 CP: I agree with Glenn, and will resist launching into a diatribe.

Where should one shop for the best selection of native, drought resistant plants?

GW: Look all over the PNW region. We really do like Xera Plants, located in SW Portland. Excellent eye for beautiful plants and very well vetted. Also, we really like Far Reaches Farm Nursery in Port Townsend.

Any good local retail nursery will offer natives, though clients need to remember that they may not be available 24/7/365! Check for local Arboretum sales, Northwest Horticultural Society, Northwest Perennial Alliance, Center for Urban Horticulture plant sales.

CP: Ditto, without the threat of a diatribe.

I’ve heard quite a bit about Big Leaf Maples and rhododendrons as indicators of changing climate. How can the average person hear what these plants are telling us?

GW: Well, if they don’t look up from their cell phones/video games, probably they won’t notice.  We have talked with fellow gardeners who were unaware…

Personally, I don’t hold out a lot of hope for the average person being aware, as they probably can’t tell you what they had for dinner last night.  Cynical? Yes, but also a lot of truth in it.

CP: What are “powers of observation,” Alex. As in Jeopardy.

Do you have any bold plant predictions for 30 years from now? Will certain plants disappear? If so, which ones will take their place?

GW: No bold predictions as invariably things happen that one could never foresee. I do think that a lot of the native plants that we take for granted, in the lowland/urbanized areas, won’t be as present/seemingly everywhere in thirty years (big leaf maples, western red cedars, lowland hemlocks and even Douglas firs where they are currently living in stressful conditions).

Ditto for sword ferns, etc. that rely on summer moisture.

CP: FIRE, FIRE, FIRE. Think about it. Look ‘around’ us. It’s only a matter of time, and we are woefully unprepared. If it hadn’t rained steadily at intervals throughout the summer, we think a lot of trees would have died this year.

I think we’ll see more oaks and other trees which don’t burn so easily or explosively, and really very few large conifers and eucalypts in residential and commercial areas. They will be relegated to parks, and larger properties, and paid better attention to, for their health and safety, and ours.  

I hope we’ll see either irrigated, moist vegetation in gardens, or spare, drought and fire resistant plantings. Not a lot of social relic plants; things that grow as weeds, then dry up and hang around as fuel all summer and fall.

Stronger fire safety ordinances, with effective public education, and fair and equal sanction for disregarding our mutual health and safety, will eventually have to become the norm, or the worst will happen over and over.

Ha, ha! Got you on that one! Bet you thought I was the most naïve fogey around! I mean, aren’t all the shrubs and trees in commercial parking lots supposed to be cubist, to the point of death?

Rhododendrons (front and center) and conifers like Dawn Redwood (bright green/yellow) and Douglas Fir (background) are among species indicating changing climate. Photo courtesy of Withey Price Landscaping.

A bonus aside from Charles Price:

I think in ‘the future of horticulture’ department, I’d add that the horticultural industrial complex will need to breed for insect health. In order to sell to an enlightened consumer base, they will need to test all their introductions for nutrition values, particularly for amino acid balance of pollen, sugar and trace elements in nectar, and label them accordingly. For example, if the nectar is very sweet, it likely won’t attract most butterflies as too thick for them to draw up their feeding apparatus, but perfect for a strong bumblebee. 

I recently purchased some lovely double flowered hydrangeas for a client. Most mop head hydrangeas still have fertile flowers somewhere on the inflorescence, often on the branchlets under the top layer of sterile florets.
The new hybrids I purchased have zero fertile flowers anywhere on them. All floral structures have been converted to petal or petal like forms, with no discernible sexual parts or nectaries.

Lovely to the eye, but too selfish for me to ever plant again. And the label noted that the plant was attractive to pollinators. Perhaps attractive (what mechanism?), but only to waste their time and energy searching in vain.

I’ll have to check everything new we consider planting more closely now, so that the materials we furnish gardens with offer more to our shared environment than looks alone.