A few weeks back I did a short presentation in Pine City, Minn., on how to build good, healthy soil, and a woman in the audience asked: “How do I know if the compost I’m using is safe?”
I’ve been wondering that same thing, I told her, explaining that I’ve been researching the topic so I have some answers, but many more questions, too. This prompted more people to weigh in on the subject, asking: Was it important to use organic compost, especially when growing edibles? How do you know that even organic compost is safe?
Does composted manure from conventional farmers contain pesticide and herbicide residue that could cause problems in their gardens? Should you have compost tested to find out what’s in it before you use it on food crops and, if so, where? And what about GMOs? Is it safe to use composted manure produced on conventional farms on which cows eat things like Monsanto’s genetically modified Roundup Ready corn and alfalfa?
Complex questions like these are difficult to answer definitively for a lot of reasons. Sometimes, there aren’t many studies, if any, on a particular topic. Or maybe there are numerous seemingly reputable studies, but many of them conflict with one another. For example, as a journalist who interviews people for a living, I can tell you that for every scientist I’ve talked to who dismisses the French study that came out last year linking a genetically-modified strain of maize to huge tumors in rats, I’ve got another scientist saying the study should be given serious consideration.Read More»
Most every commercial potting mix contains sphagnum peat moss because it’s a good, lightweight, organic amendment that improves drainage, as well as water retention and air circulation. The downside to peat moss is that it isn’t a sustainable resource. Peat moss is the decomposing remains of living sphagnum moss, and it is harvested at unsustainable rates from bogs in a manner than involves scraping off the top layer of the living moss to get to the saleable product below.
This process destroys centuries-old bogs, doing away with wildlife habitat, releasing C02 into the air, and eliminating wetlands that help prevent flooding. Because of this, conservationists and scientists all over the world have been pushing for limits and even bans on peat moss harvesting.
In Britain, for example, where peat is often burned for fuel, harvesting has become so intense that the government has set goals for phasing out peat for home gardening use by 2020. Professional growers will need to go peat free by 2030. For more information, check out the Royal Horticulture Society’s website: http://www.rhs.org.uk/Gardening/Sustainable-gardening/Peat-and-the-environment/More-about-peat.
Most of the peat used by the horticultural industry in the U.S. comes from Canada where talk of limits and bans is also heating up. So, whether you are concerned about the sustainability of peat of not, now seems like as good a time as any to explore some peat-free potting soil options.Read More»
People have been talking about straw bale gardening for years and, I admit, I haven’t really paid much attention. It’s not that I wasn’t curious about the idea. It just wasn’t on the top of my list of things to try until recently when I got the opportunity to talk with Joel Karsten about his new book Straw Bale Gardens: The Breakthrough Method for Growing Vegetables Anywhere, Earlier and with No Weeding.
Karsten isn’t just another gardener talking about straw bale gardening. He invented straw bale gardening. That’s right; he came up with the idea for a growing technique that has now become an international sensation. And it all started when he was a kid growing up on a farm right here in Minnesota.
Farmers, he told me, have no need for piles of wet, unruly straw. So when a bale would break open for one reason or another and get rained on, his family would push it up against the barn to break down over time. “I always noticed that those stacked up, broken bales would have the biggest, tallest weeds growing out of them, so I knew there was nutrition in there,” Karsten recalls, adding that he didn’t think much more about it until 15 years later.
By then, he had earned a bachelor’s degree in horticulture from the University of Minnesota, and he and his wife Patty had just bought a house in Roseville. After looking forward to gardening at their new home, they were disappointed when they realized that their whole lot consisted of little more than construction debris in which nothing was going to grow well. Then, Karsten remembered those straw bales. “And I thought, what if I just line those bales up and try growing vegetables in them as they decompose?” he recalls.Read More»
I read a lot of gardening books, and though most have something to offer, many just cover the same old ground in one way or another. So I was happy to find a copy of Michele Owens’ book, Grow the Good Life: Why a Vegetable Garden Will Make You Happy, Wealthy, and Wise, at the library recently. It was a rainy, cold weekend and I’d heard good things about the book, so I planned on curling up on the couch with it, and a couple of others I picked out. As it turned out, those other books just lay there unopened on the coffee table because I couldn’t put Owens’ book down until I finished it.
If you’re not familiar with Michele Owens’ garden writing for Organic Gardening and other magazines, you can get a good understanding of who she is and what she believes in by checking out her blog posts on Garden Rant, which she founded a few years back with a handful of similarly smart, funny and straight-talking garden writers. As a former political speech writer and author of several best-selling business books, Owens is keenly aware of the need to do her research before writing and throughout the book she cites the work of many horticulturists, ecologists, microbiologists and others. But all these facts do not a snoozy tome make because she is adept at interweaving studies, facts and figures with her own passionate commentary as an experienced gardener who loves plants, nature and growing vegetables.
Because she’s married to a journalist who covers climate change, Owens gets a dinnertime update on just how much stress our warming world is putting on agriculture all over the world. This understanding, coupled with a love of good, healthy food, drives her to motivate people, everyone, not just gardeners, to grow at least some food in their own backyards. Sure, that will help relieve some pressure on the world’s food supply, she writes. But growing things to eat is also just a joyful, uplifting thing to do; just ask anyone who has ever grown even one tomato plant in a pot on a balcony or back patio. There really is nothing like being able to walk outside and pick something you’ve grown yourself and pop it in your mouth, or serve it up for dinner.Read More»
We ripped out our lawn over the last few years, and we don’t miss it one bit. Sparse and full of creeping Charlie and other weeds, it was ugly even before our dog Lily peed all over it and killed off spots one by one. I do realize, though, that a lot of people like turf grass and, even if they don’t, they’re not keen on ripping all of it up to put in gardens that they have to care for.
But what to do about all of those weeds? The truth is, if grass gets enough sun and is kept well-watered (about an inch each week); mowed to a slightly higher height of about 3 inches, which helps shade out weeds; and fertilized even once each year, it will grow fairly well and suffer few weed and disease problems. Unfortunately, many people don’t realize the difference these simple things can make, so they hire lawn care services to come and keep their yards looking good.
Having observed these services in action all over my neighborhood, I have to say, the results aren’t so hot. Trucks show up, guys jump out, and they promptly mow the grass right down to the nub. Then, they douse the scalped grass with all kinds of chemicals, including herbicides that usually contain 2,4-D. Popular because it’s cheap and easy to use, 2,4-D was concocted by scientists during World War II. It was one of the components of Agent Orange. And it is effective when it comes to killing things like clover, thistle and creeping Charlie, but it has remained controversial since it was released for public use in 1946.
Though the EPA says there is not enough data to conclude that the herbicide may pose some cancer risk, the International Agency for Research on Cancer has classified 2,4-D as being a substance that may cause cancer in humans. Studies are divided on both sides with many scientists being of the opinion that 2,4-D may be carcinogenic, particularly in the case of Non-Hodgkin’s lymphoma. Even when these chemicals have dried, there is debate about when it is safe to come in contact with grass that has been treated with the herbicide. (You know how often you see those signs warning people and pets to stay off the grass until dry.)Read More»
We have two big, old oak trees in our yard and every fall, up until a few years ago, we would spend our October and early November weekends raking and bagging and raking and bagging until our hands blistered. Then, we would drag all those bags, bursting with leaves, to the curb to be hauled away. Every now and then, I noticed that someone would pull over, load our bags of leaves into their car and drive off. Why in the world would they want our leaves? I wondered. I soon found out.
For gardeners, or anyone with a lawn, really, fallen leaves are nutrient-rich, soil-building treasure—and they’re free! According to Mark Keaton, staff chair for the University of Arkansas Division of Agriculture, fallen leaves contain 50 to 80 percent of the nutrients trees extract from the soil during a growing season. They’re a particularly good source of nitrogen, offering anywhere from 1 to about 2 ½ percent nitrogen as they decompose.
What in the heck does that mean? Okay, figure that if a tree’s leaves offered 2 percent nitrogen it would take 100 pounds of dried leaves per 1,000 square feet to provide 2 pounds of nitrogen.That’s all the nitrogen 1,000 square feet of turf grass should need for a year, and it’s also about the right amount for a garden bed of that size, too.
But that’s not all. Research conducted by Alexander Kowalewski at Michigan State University has shown that using maple and oak leaves as mulch can help control dandelions in Kentucky bluegrass. Seriously! Go here to read that study. Unlike past studies in which leaves may have contained some pesticide residues, researchers at Michigan State used only pesticide-free leaves in their tests. And that reminds me to point out that it’s a good idea to avoid using anything but pesticide-free leaf mulch on gardens where edibles are grown.
The only hitch in this free fertilizer, and possibly weed killer, bonanza is that you need to mulch (which pretty much means shred) the leaves before you spread them on your lawn or garden. Whole leaves tend to mat down and hold moisture, causing mold and rot issues. Maple leaves are among the worst offenders because they’re so flat. Oak leaves are wavier, so they don’t mat down as thickly, which is good. But it’s still better to mulch all of the leaves you want to spread on your lawn or garden. Leaves break down faster when they’re mulched into small pieces, and they need to break down in order to make the nitrogen they offer available in the soil.
You don’t need any sort of fancy machine to mulch leaves. A regular old, cheap lawnmower will do just fine. You can watch this video we made at our house to demonstrate how to mulch leaves with a mower. Or you can just read the instructions I’ve written in the post below.Read More»