Advancing the science of gardening and other stuff since 2009
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
Susan Harris over at Garden Rant has done a terrific write up of all the details, so I’ll be brief here: Linda Chalker-Scott, the founder and fearless leader of The Garden Professors, is facing possible termination from her job at Washington State because she’s doing exactly what it says in her job description — extension, providing gardening information to the public — instead of bringing in big research grants. Universities love grants because they means money, and educating the public doesn’t. And money, more often than not, trumps little details like actual job descriptions and the educational missions of public land-grant universities.
Again, for the all the details, please see the Garden Rant post, including info on how to help stop this from happening.
I’m not sure why this is the question that just won’t die, but I got it again at a event where I was speaking recently, so I am hereby going to issue the final, official, definitive ruling on the age-old question: Is a tomato is a fruit or a vegetable?
The answer is:…
(Drum roll please)
Both!
That’s right, folks. Vegetable and fruit are not mutually exclusive categories! Fruit is a technical, botanical term like leaf and petiole and petal which refers to a specific part of a plant. Vegetable is a cultural term referring to parts of plants that we eat.
In other words: lettuce is a leaf and a vegetable, celery is a petiole and a vegetable, broccoli is a flower bud and a vegetable, and a tomato is a fruit and a vegetable.
The real mystery to me is why this question always comes up around tomatoes and only tomatoes, when there are lots of other vegetable-fruits in the grocery store. Peppers, zucchini, pumpkins, eggplants, and cucumbers are ALL fruit. And vegetables. But somehow no one seems to wonder about them.
As a beginning gardener I learned that to give plants like tomatoes and peppers more time to grow and produce the largest possible crop, it was best to start the seeds early indoors.
As soon as I learned that, I wondered: Well, if starting my tomatoes 6-8 weeks before transplanting them outside is good, surely 10 weeks would be better, right? Or 12? Or 16?
Turns out, earlier isn’t always better, and here are some of the reasons why.
First, you probably don’t have enough light. If, like most home gardeners, you are starting seeds under florescent bulbs, it is difficult to give sun lovers like tomatoes and peppers enough light. Light intensity drops off rapidly as you move away from the bulbs, so you know to keep the bulbs right above your seedlings. This works great when the plants are small, but as they grow it becomes very difficult to give both the tops and the bottoms of the seedlings enough light. The result is dying lower leaves and spindly, unhealthy growth.
Secondly, you are almost certainly going to get some crappy root systems. If you’ve followed this blog for a while, you’ve no doubt read Bert and Linda talking about all the potential problems with the root systems of container grown trees and shrubs. Well, most of the same problems develop with other plants grown in small containers. The roots start circling and they are slow to grow out of the rich soil of the container and into the native soil around them once transplanted into the garden. The longer your transplants grow indoors, the more likely they are to develop problematic root systems. Keeping transplanting them up to larger and larger containers can help mitigate the problem, but that quickly takes up far more space than most home gardeners have for there seedlings.
How big and impact that circling root system will have on the health of the plant varies by species. My personal experience growing zinnias, for example, is that they handle circling, pot-bound roots so poorly that plants from seeds sown directly in the garden quickly over-take and out-perform plants started weeks earlier indoors.
So follow the recommendations for the timing of seed starting. It really does work better. You should be able to get advice on when to start seeds from the catalogs you are shopping, extension offices, or you can use Margaret Roach’s excellent seed sowing calculator.
If you DO decide that earlier is better, that you can provide the light and generous pot sizes to avoid problems, there’s no harm in giving it a shot. But if you do, try starting a second batch at the later, recommended, time and growing the two side-by-side in the garden so you can really compare and see which perform best in the actual conditions of your garden, and if all that extra time and space under your lights or in your greenhouse was really worth it.
We are now headed into the dark part of the year. The winter solstice is less than a month away. For the moment, however, let us think not about these short days and long nights, but back to the summer—and especially to summer’s brilliant flowers. How do all these colors come to be? What allows us to perceive them? Why don’t we see the world in the black-and-white of old-style photographs?
Let’s start our exploration of these questions in the northwestern corner of Washington’s Puget Sound, a stone’s throw from the Canadian border. Here lie the San Juan Islands, hundreds of islands, islets, and projecting rocks so beautiful that people sometimes ride the ferry just to glimpse them from the deck, never even getting off to walk on land. These complex and convoluted landforms are home to thousands of birds and marine mammals, their shores are decorated with exotic-looking creatures bumping up on one another, and every bit of soil is covered with rich vegetation—stands of Douglas fir and cedar, a bright coastal fringe of madrones with their vivid red-orange bark and brilliant white blossoms, and grasses that turn golden with the advance of summer. In the spring the islands are carpeted with wildflowers, and none more richly than eleven-acre Yellow Island.
Yellow Island has been owned and protected by The Nature Conservancy since 1979. Its flora is basically intact, the way it once was on all the islands, and in the spring it is brilliant.
The photographer finds it hard to move forward, there are so many sights to delight the eye and invite a picture. The biologist is thrilled that such a place still exists, so close to the densely settled metropolis of Seattle and its surrounding cities. And I, in addition to these feelings, find myself marveling at the colors themselves.
All the Colors of the Rainbow
The plants on Yellow Island glow with literally all the colors of the rainbow, from blue, through green and yellow, and on to orange and red. They call out a question that scientists and philosophers have asked literally for centuries—how do leaves and flowers come to have the colors they do? Indeed, why are objects of any kind seen by us as having distinguishable colors?
The sensation of color is an everyday aspect of conscious experience for most of us, but what makes it so? It needn’t be, for we are all familiar with a world without color, as portrayed in the marvelously evocative black-and-white prints of master photographers. It is also different for those who have some form of colorblindness.
For us to experience a colored world requires the operation of many mechanisms, not all of which are understood by today’s science. The foundation of the entire complex chain of processes leading to conscious experience is, however, the interaction of light with molecules. Inasmuch as there are two partners in this interaction—light, and the molecules that are affected by light—we will need to consider both of them.
Let’s start with light, particularly sunlight, the natural light in whose presence all life on Earth evolved. Thermonuclear reactions occurring within the Sun emit massive amounts of energy that streams out in all directions, through the solar system and beyond. The total quantity of solar energy reaching the Earth is just right to warm the planet to a temperature that has enabled the evolution of life. It arrives on Earth’s surface in the form of a vast range of wavelengths of electromagnetic energy, from the extremely short-wavelength and highly energetic gamma rays and X-rays at one extreme, to the long- wavelength, low energy radio waves at the other. Between these two ends of the total electromagnetic spectrum the ratio of wavelengths (and hence also of energies) is 1018, or 1 followed by 18 zeros. Gamma rays are of atomic dimensions, so short that we have no sensory experience to compare them to, while radio waves are measured in miles. Nevertheless, their basic nature is the same. Extraordinary!
Visible light is a tiny, tiny slice of wavelengths in the middle of this vast range, with ultraviolet (sunburn!) just to the shorter wavelength side, and infrared (heat!) to the longer wavelength side. The spectrum that underlies our experience of light and of the visible world runs from violet to red. Here is what this spectrum looks like on the ceiling of a friend’s apartment, with the colors separated by a faceted glass ball she has hanging in her west-facing window.
And here is the same spectrum seen in a rainbow over the rolling plains of Montana, north of Yellowstone National Park.
Rainbows and Flowers
The sunlight that reaches our Earth literally consists of all the colors of the rainbow. But what about the flowers? How do we relate the colors contained within the apparently colorless light that is shining on a meadow to the colors we experience as being the property of the buttercups, the camas, and the paintbrushes?
To come to a deeper understanding, think about a colored liquid that you can handle easily yourself, say red food coloring. You grasp the tiny bottle, squeeze a few drops into a small glass of water, and voilà, you have red water. White light shining in from one side of the glass emerges as red light from the other side. Test it. If you let light shine through the glass and onto a sheet of white paper, you will see a patch of red.
What happened to turn the white light that entered the glass into the red light that exited? When light struck the dye molecules that were dissolved in otherwise colorless water, some wavelengths of light were selectively absorbed. If they were absorbed, they could no longer pass through the solution and be seen on the other side. The color of the light exiting from the solution, therefore, is due to the wavelengths that were not absorbed.
This is a bedrock principle that underlies our experience of color, and that we will explore in several subsequent posts. Molecules absorb some wavelengths of light and fail to absorb others, and the wavelengths that are not absorbed are ones that can reach our eyes and be seen. Notice that there are two partners dancing to manifest this principle, the light and the molecules absorbing the light. This partner dance will be our foundation as we explore the amazing realm of color. For now, just go out into the world and pay attention to the colors you see, being grateful for the privilege.
At the top are Petunia integrifolia (purple) and Petunia axillaris (white) and below are an assortment of flowers from a population of F2 hybrids between the two. This cross is interesting because it is a recreation of the original hybrid that created modern hybrid petunia.
But more fun is a similar cross with the one hummingbird pollinated petunia, P. exserta! It is fun to see the ways the colors and flower forms recombine in new ways in the seedlings.
I don’t have anything profound to say about these pictures… just, hey, isn’t genetics cool?
Joseph Tychonievich
For normal people, I gather, New Years is all about making resolutions to loose weight or spend more quality time with family. For me, New Years means reviewing everything I grew in the garden in the past 12 months and deciding what I love and what I’m over. I always try lots of new things, and so I thought I’d share my top new favorites for 2015.
The only Dianthus chinensis I’d grown before are the modern selections which are about three inches tall with huge flowers and as ugly as can be (in my opinion) but ‘Chianti’ and ‘Victoriana’, two charming old-fashioned seed strains won my heart in a big way this year. Annuals, very easy from seed, and blooming all summer with these wonderfully romantic double blooms that made wonderful, long-lasting cut flowers. I’m hoping they decide to self-sow and return next year.
Poplars are, generally, terrible trees. Weak wooded, short-lived, and weedy with few redeeming characteristics. But I bought this Golden Poplar, Populus alba ‘Richardii’, on a whim, and am absolutely thrilled with it. The foliage stays this bright, beautiful shade of yellow all summer, even in full sun (or at least what passes for full sun in cloudy Michigan) without burning. Great in the garden, and cut branches look amazing in a vase. I suppose it could eventually get large, but I’m planning to keep pruning it back hard to the ground to force it to push out lots of lush, long new stems of bright leaves.
I love breeding plants, and for the past few years I’ve been deeply obsessed with breeding gladiolus… I had a lot of new seedlings this year, but this one, a cross between the wonderful variety ‘Little Comet’ and one of my unnamed hardy varieties I call h2.3, is my favorite of the year. I just LOVE those colors, and love that the come on a strong stem that doesn’t need staking. If it keeps performing well, I’d love to make it available for sale in a few years.
Finally, I forgot to get a picture of this, but I have a new favorite tomato! For years, my favorites have unequivocally been ‘Black Krim’ for large tomatoes, ‘Matt’s Wild Cherry’ for cherries, and ‘Opalka’ for paste, but ‘Black Krim’ has been replaced! My new favorite: ‘Sweet Scarlet Dwarf’ This plant combines a wonderful compact, tidy, attractive growth habit with big yields and really terrific flavor. It isn’t widely available (the only source I know is Heritage Seed Market) but do track down some seeds. You’ll be happy you did.
Now, please, let me know your favorites in the comments so I can expand my shopping list for 2016!
Here in Michigan – and, it seems, most of the Eastern US – we’ve been having unseasonably warm weather and there are odd things afoot in the garden. Some plants that would normally be dormant coming back into growth. But perhaps odder is that while some plants have been “fooled” by the unseasonable heat, others are still resolutely dormant and not pushing any growth at all despite the warmth. Why is that?
There are a lot of factors that determine when a plant is dormant and when in active growth, a key one in this context is whether they have a vernalization requirement or not. In simple terms, some plants, once they go dormant for the winter, will refuse to come back into growth until they’ve experienced a period of cold temperatures. Once they’ve been through that cold, the plant is termed to be vernalized and will then burst into vigorous growth as soon as the weather warms up again.
You’ve probably run up against a vernalization requirement in terms of bulbs like tulips. That requirement is why you need to give tulip bulbs a cold treatment in order to force them to bloom indoors, and why southern gardeners without sufficient natural winter cold have to pre-chill their tulips in order for them to bloom. The adaptive advantage of this is obvious in a year like this, as it prevents plants from jumping the gun in a mild December and getting damaged by the real cold when it arrives.
So why do are some plants lack this adaptation and come into growth in a freak warm spell? Some are adapted to life warmer climates and sometimes it is the work of humans. Modern hybrid roses, for example, have had their vernalization requirement bred out of them. The downside is that this makes them more susceptible for winter damage sometimes, but the plus side is that it is part of what causes them to bloom all summer long rather than just once in the spring the way most of their wild ancestors do.
Last year I was in England, and a snowdrop obsessive there (aka, a Galanthophile) showed me this cool trick, using mesh pots to keep her vast collection of different varieties organized.
She puts her bulbs in these pots (designed for use in hydroponic systems, I believe), and then sinks the entire pot down in the ground, so that the pot is invisible. The pot keeps the bulbs contained and easy to find so you can dig them up to divide or share even when dormant, and keeps different varieties growing next to each other from getting mixed up. But unlike a regular solid-sided pot, the open mesh allows roots and water to move freely so the bulbs grow just as easily and with as little care as if they were planted directly in the ground.
I’m not a snowdrop lover, they frankly bore me, but I have been getting more and more obsessed with bulbous corydalis, selections of C. solida and the amazing true blue Corydalis turtschaninovii. The tiny bulbs are impossible to find once they get dormant, and my collection is already beginning to get mixed up as the different varieties begin dividing and encroaching on each other… I’m going to start planting new editions in mesh pots to keep everything organized.
The seed catalogs have started showing up in the mail, and a great number of them include something like this on the first few pages:
Here’s the thing: NO ONE is selling genetically engineered seeds to home gardeners. There is one company, funded by kickstarter, that is trying to sell genetically engineered seeds of a glow-in-the-dark plant sometime in the future (though, like a lot of kickstarter project, the actual release date keeps getting delayed) but other than that, genetically engineered varieties are only being sold to commercial farmers, and only after the farmer has signed a pretty comprehensive licensing agreement.
You can go to the store and buy food made from genetically engineered varieties — essentially anything that contains corn and isn’t labeled as organic will be — and you can stop by the pet store and pick yourself up a fish with jellyfish genes, but no one is trying to sell you genetically engineered seeds.
So those pledges in seed catalogs promising they contain no GMO seeds are technically true, but also pretty meaningless. So if you are worried about accidentally getting a GMO variety, don’t be. And if you wish you COULD grow one, sorry, you are out of luck, unless that kickstarter project ever actually gets up and running.