Every year I teach a class called nursery management. In this class students have the opportunity to try all kinds of different growing techniques out in the nursery. They get to use a tree spade and prune and all kinds of other stuff. But something else that I have the students do is to make hydroponic systems for growing plants. No, hydroponics is not a common technique for growing plants in a nursery, but to grow plants hydroponically you need to know what you’re doing, and so this is a convenient way to make the students think about the plants they grow and what these plants need to prosper.
To start this project I give the students a water pump and an air pump (courtesy of our friendly neighborhood drug dealers — no, seriously — when the cops bust pot growing operations they give us the equipment that they’ve confiscated after they’re done using it as evidence. Much of the equipments is new, some is very high end.) Then I divide the students into a few groups, tell them what they’re growing, and give them two weeks to come up with a growing system and a nutrient solution to grow their crop (I do allow them to use our stock hydroponic solution, which will grow the plants, but won’t win anyone any prizes — most groups choose to use this as a base solution and then add to it.). The group whose plants grow the largest after twelve weeks wins a modest bonus to their grade.
So, what do we have for set-ups this year? Some very, very cool ones! First, we have a number of groups who went with a simple, non-circulating system, as seen below. Basically just an air-hose and a container filled with nutrient solution.
Another group decided to use a flood and drain system. They use a timer to trigger the water pump to fill a tray with nutrient solution for five minutes every few hours. This hydrates the containers which hold the extremely well drained ceramic beads in which the plants are held.
And finally, one group decided to use a capillary action system where the base of the container is filled with nutrient solution which is wicked up into a well drained media (a combination of rockwool, vermiculite, and perlite) into which the plants are placed. This group decided to lay their plants on their sides to encourage extra root growth.
I’ll let you know in about 12 weeks which group wins!
…because apparently they can fly:
I recently heard that Mike Dirr has come out with the next edition of his book on woody landscape plants. Dr. Dirr (I can’t seem to bring myself to call him Mike, even after all
these years) was my major advisor in graduate school, so I’m really looking forward to getting it. In the meantime I heard that he included a section on my thoughts about how to spell the scientific name of the butterflybush, a plant that I worked on to get my Ph.D.. Some people spell it Buddleia, but most go with the Buddleja spelling — but it looks really silly. So, while I’m not sure exactly what Dr. Dirr wrote, I thought I’d give you my two cents worth.
By the way, any of you out there yelling and screaming that I shouldn’t be promoting an invasive weed should be ashamed of yourselves. I spent years working on this plant and I
refuse to believe that all of my work was for naught!
But back to the name. First of all you need to understand that the Butterflybush was originally named for a botanist named Adam Buddle. Buddle didn’t discover this plant. Nor was he directly involved with its naming, being an expert on mosses. Besides, he wasn’t even around when Butterflybushes were discovered by the western world around 1730 (Buddle died in 1715).
Buddleja was first mentioned in Species Plantarum, a book by Linnaeus. And, when it was listed there, it did have that j in it. OK, so far it makes sense to spell the name Buddleja.
BUT, in his later works, though this plant was spelled Buddleja in the text of the book (at that time stylized print settings meant that i’s were printed as j’s u’s as v’s as s’s as f’s), in the index – where the stylized text wasn’t used – Buddleia was spelled with an i. Hence I submit to you that Buddleia should be spelled with an i – though I’m not nearly as fanatical about it as I once was.
[To those new to our blog, there are many past posts of scientifically-proven garden advice and research results…so pardon if we slip off the wagon just briefly.]
In response to the previous post:
Dr. Gillman, I’m simply shocked at your sloppy “materials and methods”.
What is that, a Frisbee? And you drink a beer called Moose Drool? Sounds intriguing, but probably too hoppy. No wonder the slugs were simply mocking your feeble attempts at attracting them.
BEHOLD the well-researched and insightful slug trap:
One 12″ plastic pot saucer + 10 oz. Pabst Blue Ribbon = 28 slugs in one night.
Not unlike college students, results indicate there’s obviously no accounting for the slug’s taste (or lack thereof) in beer. Hmmm…that gives me an idea for a grant proposal…
Around my home I have gravel and hostas. Just perfect, as you might imagine, for lots of slug damage. This is where I do my work on slug remedies. And there are lots of remedies for slugs! One of the oldest of these remedies is beer. Almost any beer will be adequate (including alcohol free), but generally the darker the beer the better. When I first started testing different cures for slugs about five years ago one of the first ones that I looked at was beer. And when I first tried it…..well, see for yourself.
This is the way that I set up my first beer trap (for this test). There’s fine sand all the way around the trap and the trap is filled with Moose Drool (a nice beer — Suzanne, my wife — was actually a little irritated that I wasted a good Moose Drool when we had a Bud Light in the fridge — But I was only thirsty for half a beer when I set it out….and I don’t like Bud Light)
I set this trap up around 8 o’clock on a nice warm summer evening, the idea being that the next morning I could go out and see how many slugs approached the beer (by looking at the sand) and then see how many slugs the beer actually caught.
As you can see below we had quite a few slugs approach the beer (By my count about twenty). And guess how many dead slugs were in that beer?
If you guessed 20…you’d be wrong! There were no slugs in that beer. Why? Because this is a poorly designed slug trap! slug traps are best when they are made with something like a mason jar and that jar is buried up to the lip of the jar in soil. Then the jar should be filled up to within about an inch of the top with beer. If you fill it higher the slug will be able to just reach his head in and drink. In fact, after I set this trap out, I spent much of the evening watching slugs do just that — it was actually a little like watching old episodes of Cheers! I had names for the slugs and everything (like Norm and Frazier and that mailman guy whose name I can’t remember now…).
So slug traps are good — but only if they’re set up right!
It’s a nice sunny September day in Seattle and I’m in my happy place. What better topic to match my mood than mulch?
For those of you not familiar with my fixation on woody mulches, I’ll refer you to an article in MasterGardener Magazine here. Briefly, I am a fan of coarse, chunky organic mulch, particularly arborist wood chips or other chipped material from trees and shrubs.
Rather than send this material off to the landfill, it’s so much better to use it as a protective layer on top of your landscape soil. It’s a cheap, natural way to protect and nourish your plants, and provides a great habitat for beneficial insects and microorganisms.
Practically speaking, how does one move a mountain of mulch? Shovels don’t work well, and compost forks have too much space between tines. My favorite tool is the mulching fork. It’s relatively lightweight, well balanced, and makes quick work of wood chips.
Sometimes you’ll find twigs in your mulch pile, or might have your own woody prunings that you’d like to use as mulch. My second favorite tool is my electric chipper/shredder. It’s powerful enough to deal with small branches and twigs and helps me create a more uniform mulch. Plus, I reuse my yard waste and keep the nutrients on site rather than throwing them away.
I don’t own stock in either of these products (my faculty salary doesn’t exactly allow me to be an investment tycoon). They’re just a few of my favorite things…
Sometimes I feel guilty because I always seem to be putting down the products that people sell to make their living. But not today! Today I’ve got something that actually works! No, it isn’t pretty, and it does have some irritating problems, but I can honestly say that it does what the company that manufactures it says it does. And that product is the Aqua Globe.
This is a very simple contraption (which is part of the reason that it works). It’s just a glass ball with a hollow tube connecting to it. At the base of the tube there’s a hole where water can be poured it to fill the globe. When you push this into a container it will release the water in the globe slowly and give an extra day or two between waterings. This contraption doesn’t affect the drainage of the media that you put it into, and it works with most types of media.
The down side to this thing is that….well….it’s kind of nasty looking. The other problem with it is that, after you push it into the potting soil, it’s hollow tip will fill up with media, so when you fill it with water the next time you need to dig that media out with a fine-bladed knife or a thick piece of wire. But hey, if you’re going on a short vacation and you’re feuding with your neighbors, then this little contraption will do the trick.
There was an article published recently that traced the melting of glaciers in the US over the last 50 years. This study showed, pretty convincingly, that the glaciers are, indeed, melting, and melting rapidly. Meanwhile, in our atmosphere, levels of carbon dioxide from humans burning fossil fuel are increasing in a manner roughly correlated to the increase in temperature that’s melting the glaciers. But is the carbon dioxide actually causing the warming? Believe it or not this is still an area of discussion among scientist, and the answer isn’t as simple as many newspapers make it out to be. Almost all of the scientists that you care to talk to, even those skeptical of the role of carbon dioxide in global warming, admit that increasing carbon dioxide is going to cause a net increase in global temperature. But there is a decent amount of research out there showing that solar and geothermal activity (in other words things that we can’t control) may cause anywhere from 15 to 75% of the warming that we’re seeing. To be honest, based on what I’ve read (and I’m no climate scientist), I tend to side with those who believe that global warming is mostly caused by human releases of carbon dioxide, but I also think that to accept that theory as proven is a mistake.
In my humble opinion we’re missing the more compelling reason to reduce our emissions of carbon dioxide (besides the fact that we’re running out of fossil fuels of course). Plants. Most people simply assume that, temperature increases aside, increasing carbon dioxide in the atmosphere is going to be good for plants, and that’s just not the case. True, some plants, like Canadian thistle and many other weeds, love the increase in carbon dioxide, but other plants, such as many grasses, just don’t respond to it that well. The ironic thing is that, for those plants that respond strongly to CO2, nutrients like nitrogen and potassium are taken up quickly from the soil (as you’d expect with a rapidly growing plant) and then, as the nutrients in the soil run out, the growth of the plant is drastically reduced. In other words, CO2 causes unfertilized soils to become more rapidly depleted. So what does this all mean? It means that as we increase CO2 levels in the atmosphere we’re changing the world’s ecosystem, including the fields that grow our crops. Indeed, we’re actually adjusting the atmosphere to alter which plants are most appropriate for certain situations. There are even those who argue that, because of our CO2 emissions, we’re encouraging invasive plants to take over our native forests because these plants tend to be able to handle high CO2 (and high temperatures) better than the plants that are already there.
To me this is the more important reason to reduce our carbon footprint.
Part of the problem with being a professor is that companies assume that I have a bottomless supply of funds to test their products and that it is, in fact, my duty to do so. And of course they assume that this testing will ultimately find their product useful.
The truth is that I do love to test things, but I don’t have the funds to do the comprehensive tests that these companies usually want, at least not without them helping out at least a little – and most of them don’t want to spend money on tests! But many times, even if I tell them on the phone that I’m not likely to test what they’re selling they’ll send along a sample anyway, hoping that I’ll be curious enough to give the stuff a shot. And I usually let them because, well, why not?
Anyway, that brings me to this pile of ash that is currently sitting on my floor. A guy from a company (which I will decline to name) called me on the phone and convinced me to accept about 25 pounds of rice hulls that had been burned to ash while being used to fuel something or another (I can’t remember what and there was no note in the box). This ash is supposedly the cat’s meow for helping the media in containers to retain water and this guy wants me to test it. I told this guy that I was unlikely to have time for it, but he was insistent. I guess he thought that if the stuff sat on my floor long enough eventually I’d get curious, open the box, and try it out.
Turns out he was right.
So I get this box full of ash, open it up and am immediately hit in the face with black dust which I wisely (and accidentally) inhale. Lovely. Then I take out the MSDS sheet (Material Safety Data Sheet – required for most chemicals) and read about the problems with this product. It turns out this stuff contains crystalline silica (no surprise there, rice hulls are full on silicon), which can cause a rapid onset of silicoses as well as being a cancer hazard (crystalline silica is a known carcinogen if it’s inhaled).
Now I don’t want to blow the danger of this stuff out of proportion. I have little doubt that my exposure to it wasn’t enough to do anything terrible to me (just as I’m pretty sure that the two packs of cigarettes or so that I smoked during college aren’t going to eventually lead to lung cancer). And I’m all in favor of using industrial byproducts for other purposes whenever possible. But my goodness, this stuff is ash! It just flies into the air! I just can’t see how, even with the recommended protection, nursery workers could avoid inhaling this stuff on a daily basis if they were using it to pot up plants (perlite is pretty bad – but this stuff is worse) — which just seems like a heck of a bad idea. In terms of the ability of this stuff to hold water….well, I put some into a plastic container with some water which the ash absorbed none of. All that said, it might be possible that this stuff helps container media to hold more water, but for an unintended reason. This ash is extremely fine. When we mixed it with container media it quickly found its way into all of the pore spaces between the media particles making the media more like clay than media. This did potentially increase the media’s ability to retain water, but decreased its ability to hold air – which is not a good thing for young roots. So the quick and easy summary is that rice hull ash is not the best idea for containers.