28 March 2011

Preparing soil: Dig? Till? Spray?

As spring inches its way nearer, I've been figuring out all my plans for the garden this year. As usual, my seed shopping got a little out of hand, and I'm not going to have NEARLY enough ground for everything I want to grow. (Note to self: Next year, try to get interested in breeding plants that take up less room than corn and squash...)

Early last fall, I got busy preparing a bunch of new beds using my default method: sheet composting. I put down a layer of newspaper or cardboard and cover it with a nice layer of compost and then wood chip mulch. Done in the late summer or early fall, it nicely smothers the grass and weeds, and the newspaper breaks down, wormies get busy mixing loosening the soil, so that by spring you have a nicely mulched bed all ready to plant up.

But it takes time, and I need space, in a hurry, this spring. What's a fellow to do?

I used to turn to tillage. With a shovel, or a tiller, physically turning the soil over to kill the plants at the surface. It is how mankind has cleared land for farming and gardening practically since agriculture began but I've been rethinking that. Science has pretty clearly shown that tillage is pretty bad news, destroying soil structure, disrupting the vibrant and vital network of soil organisms, and making the soil vulnerable to erosion by wind and water – think the dust bowl. Now think how all that eroded soil effects life in the rivers and wetlands where it ends up. As a one-time event to prepare new ground, I don't think tillage it is a terrible option, but still, I'd rather avoid it if I can.

There are other options to clear soil for planting. You can cover the soil with clear plastic to trap the heat of the sun and bake out all the plants -- an option that doesn't really work in a cool, cloudy, Michigan spring, and I can't imagine is good for the soil biota anyway... If it is hot enough to kill plants, it has got to be hot enough to kill earthworms, beneficial bacteria and fungi. The same goes for boiling water (not to mention the distinct possibility of burning myself in the process...). And I'm not going to try the highly concentrated acetic acid (aka, vinegar) organic weed killers. I work with concentrated acetic acid in the lab. I wear goggles, gloves, and pour it in the fume hood. A little acetic acid is lovely for dressing a salad. A lot of acetic acid is incredibly caustic and will make you pretty unhappy if you spill it on yourself. Also not much good for the good things living in the soil. We use vinegar to preserve pickles because it kills bacteria and fungi. I'd rather not have pickled soil, thank you.

So, I wondered, what about glyphosate? The chemical you probably know as Round-Up, though it is off patent now, so there are oodles of cheaper, generic brand glyphosate-based herbicides on the market to choose from. I'm not generally one to be spraying stuff in the garden. If a plant has disease or insect problems, I rip it out and find something better to grow. When it comes to pesticides, it is pretty clear that not spraying anything is better environmentally than spraying something, but when it comes to preparing new ground, I'm not to sure. Which is less bad – tilling, or spraying glyphosate?

Glyphosate has some obvious advantages over tilling: less work, doesn't disrupt soil structure, leaves the soil covered and stabilized with dead leaves and roots to prevent erosion – but that could all be for naught if it does something wretched to the soil once it gets in there. So, I decided to do a little nosing through the scientific literature and see what I could find.

My first question was, is this stuff poison?
What I could find is that it is incredibly non-toxic. Essentially everything will kill you at high enough doses or if injected into the right part of your body, but glyphosate is pretty hard to do it with. There are a very few studies that find damage in very specific situations like embryos growing in petri dishes, but virtually everything will harm exposed cells in that situation. Based on what I can find, you should be more worried about everyday things like, say, shampoo.

Fish are something if a special case. Glyphosate itself is essentially harmless in water, and rapidly degraded by microorganisms in waterways. However, when it is made into products like Round-Up it is combined with surfactants -- essentially, soaps -- which break up water's surface tension and help it stick to leaves. These surfactants, applied directly to natural water ways, are not good for most of the things that live there. Don't let it drift onto your pond. But the same goes for your dish soap. Again, this stuff seems to be fairly harmless.

Glyphosate is, of course, highly toxic to plants, which is what it is supposed to be, but it pretty much has to contact leaves directly. Once it hits the soil, it is quickly bound up and inactivated by soil particles, and then degraded completely by soil organisms to nothing but CO2. Which is why you can spray one day and plant seeds the next and have no problems.

But what about earthworms and mycorrhizae, and all the other little good things that live in the soil? I'd not heard the topic discussed before, so I was very intrigued when I saw papers with titles like Effect of Glyphosate on Soil Microbial Activity and Biomass and Glyphosate toxicity and the effect of long-term vegetation control on soil microbial communities.

I was also very surprised by the findings. Adding glyphosate increases soil microbial activity. All the little bacteria and such are breaking it down, consuming it like they do compost or other soil organic matter. Long term there is essentially no effect: you add the glyphosate, there is a little burst of activity as it gets gobbled up, and then thing go back to normal. Even repeated applications over the long-term didn't change the make up of the soil biology.

At the end here, I'm left with the conclusion that glyphosate is a better bet ecologically than tilling. If I have the time, my first choice would always be sheet composting, but if I need ground cleared in a hurry, tillage has clear and well documented negative effects on soil and water quality, while glyphosate comes out looking much cleaner. It isn't the conclusion I expected to reach, but I think I will be using glyphosate to prepare my last minute beds this spring.

25 March 2011

Friday Cartoon: Roadtrip (from the archives)

Life has been crazy of late, so I decided to dig up an old drawing for you all this Friday. And important tip to keep in mind as you start planning your summer vacations:
Road trip with a gardener

21 March 2011

The Survivors

The snow has melted, crocuses are blooming, and it is time for my annual "I wonder what survived" tour of the garden.

We had what I thought was a pretty average winter -- some serious cold, but nothing too intense. I was worried because we didn't have very good snow cover (snow = nature's blanket) but so far things look great!
After having it 4 years, you'd think I'd have gotten used to this Agave parryi actually being hardy, but every winter I'm happily surprised to see it come through unfazed. Some years the tips of the leaves get damaged it they weren't covered with snow in the very coldest weather, but this year it didn't even get that. It has decent drainage in this spot, which I think is a big part of my success.
This is one of my snapdragons... Pretending to be alive, though I'm pretty sure it isn't. I don't know why snaps do this for me -- it seems they always come out of winter looking fine, and then collapse once actual spring arrives. Little teases...
When I saw the slimy wet mass at the heart of this cardoon, I thought it was a gonner, but looking closer I see a tiny fat white shoot coming up to one side. We'll see if it actually pulls through.

I was VERY surprised to see this bud pushing up through the mulch. It is an Anemone coronaria, which I've always seen listed as zone 7 or even 8! I grew them as an annual last year, and figured that was that. But apparently not! And I'm not the only one. Kylee over at Our Little Acre (also zone 5 -- just a little south of me) said she's had them come back for the past three years!

So, very good news on the winter survival front here! I am SOOOOOOO excited about the gardening year starting up! Let me leave you with some totally gratuitous crocus shots:

16 March 2011

The Ghost of Gardeners Past

I saw a ghost while bicycling home today, just a flash of white on a bank of tangled scrub.

I stopped, and taking a closer look, found a glorious drift of snowdrops
Clearly, a ghost of a gardener. A gardener, in fact named Veronika Vitums. How do I know that? Well, just at the top of that bank of snowdrops, I found this:

Snow drops nestled up against the gravestone of someone who loved them very much.
Even in death, gardeners can't help but send out flowers into the world to celebrate the arrival of spring. I don't know who Veronika was, but I think we would have got on. And I thank her very much for the beauty she sent out into my life today.

11 March 2011

First crocus of the year!

(And, in the background, though you can't really see it, is my agave -- still alive! Take that, winter!)

07 March 2011

Learning to love what I love

When I started seriously gardening in my teens, all I grew was roses. I wanted those huge, opulent, complex, fragrant flowers. I would flip through catalogs and books, totally absorbed in the incredible close-up images. When my own plants produced their first blooms, I bent down, cradling them in my hands like a lover, their scent, texture, and color filling all my senses. Pure joy.

Then I started getting educated. I read books on garden design, got the my first horticulture degree, and learned about things like foliage and year-round interest. I learned that focusing totally on lovely flowers was a rookie mistake, that “real” garden designers grow plants with leaves and stems that look great for months and months rather than flash-in-the-pan effect of floral drama queens. I'm grateful for that education -- it lead me to learn to appreciate the simple, reliable joys of plants like cardoons and bronze fennel.

Somewhere, though, in learning what I "ought" to love I lost track of some of the things I actually love. It turns out that, though I like reliable backdrop plants that look great all year, what I really love is the ephemeral. I WANT my garden to flare up in gorgeous color one day that is gone the next. That's why I live in Michigan. I love spring, and summer and fall, the change, the dynamism. I even love winter – the long peace, the planning, the slowly, tortuously building anticipation that leaves me literally shaking, dancing, laughing with joy when those first crocuses and snowdrops show themselves.
 Steady, reliable performers that don't have an off season are all well and good if you are designed a landscape for a business or park that needs to look good all the time. But I want more in my home garden. I want drama. I want anticipation. I'm happy to accept some ungangly forms or awkward bare spots in exchange for those thrilling, long-awaited moments of sheer perfect unimaginable beauty. The peonies, lilies, tulips, roses, gladiolus, chrysanthemums and all the rest.

I've learned to laugh it off when someone pulls out the tired old line about mature gardeners focusing on foliage rather than flowers. I'm going to plant what I love because I love it, let the designers and experts think what they will. I'd rather be deliriously happy than 'right' any day.